tag:blogger.com,1999:blog-25290841040416401722024-03-13T09:31:51.438-07:00Vehicle Diagnostics GuideAnonymoushttp://www.blogger.com/profile/07884952301771193295noreply@blogger.comBlogger19125tag:blogger.com,1999:blog-2529084104041640172.post-29645950836396637272017-01-09T12:19:00.000-08:002017-01-09T12:19:28.208-08:00Engine & Driveability Problems: 14 Engine Hesitates or Stumbles When Accelerating:<center style="font-family: Arial;">
<img alt="throttle hesitation" height="250" src="http://www.aa1car.com/library/throttle-by-wire_maxima.jpg" /><br /><h1>
Problem: Engine Hesitation</h1>
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Hesitation is when your engine misfires, stumbles or lacks power when you accelerate or step on the throttle. The problem often means the air/fuel mixture is not being properly enriched or is going lean, or the ignition system is weak and is misfiring when the engine comes under load or the air/fuel mixture goes lean.</div>
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When you step down on the accelerator and the throttle opens, the engine sucks in more air. The computer should respond by adding more fuel.</div>
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If the engine has a speed-density type of fuel injection system (no airflow sensor), the computer uses inputs from the throttle position sensor, manifold absolute pressure sensor, air temperature sensor and engine rpm to estimate airflow and how much fuel the engine needs. </div>
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<b>NOTE:</b> Speed-density systems are much less sensitive to vacuum leaks than EFI systems that use an airflow sensor.</div>
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If the engine has an airflow sensor (vane airflow or mass airflow), it looks primarily at the airflow signal from the airflow sensor, but also takes into account what the throttle position sensor and MAP Sensor (if equipped) are telling it. <b>NOTE:</b> Airflow EFI systems are very sensitive to vacuum leaks, and air leaks downstream of the airflow sensor.</div>
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Consequently, if the inputs from any of these sensors is inaccurate or missing, the engine computer may not add enough fuel, allowing the fuel mixture to go lean causing a misfire that produces a hesitation or stumble when accelerating or opening the throttle.</div>
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The amount of fuel added by the computer when the throttle opens may also be insufficient if the fuel injectors are dirty or fuel pressure is low. The oxygen sensors in the exhaust monitor the air/fuel mixture so the computer can adjust fuel trim as needed to maintain the proper air/fuel ratio. Fuel trim adjustments can compensate for dirty injectors and/or low fuel pressure to a certain extent, but occur too slowly to offset a throttle hesitation problem.</div>
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Vacuum leaks will typically cause the fuel trim to run rich as the computer tries to compensate for the extra air being sucked into the engine through the leak.</div>
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Possible Causes of Engine Hesitation or Stumble:</h3>
<br style="font-family: Arial;" /><span style="font-family: Arial;">* Dirty fuel injectors</span><span style="font-family: Arial;"> (cleaning the injectors often fixes this).</span><br style="font-family: Arial;" /><span style="font-family: Arial;">* Bad MAP (manifold absolute pressure) sensor</span><br style="font-family: Arial;" /><span style="font-family: Arial;">* Bad TPS (throttle position) sensor</span><br style="font-family: Arial;" /><span style="font-family: Arial;">* Bad or dirty MAF (mass airflow) sensor</span><br style="font-family: Arial;" /><span style="font-family: Arial;">* Low fuel pressure (leaky fuel pressure regulator, weak fuel pump or low system voltage or charging voltage that causes the fuel pump to run slow)</span><br style="font-family: Arial;" /><span style="font-family: Arial;">* Vacuum leaks (intake manifold, vacuum hoses, throttle body, EGR valve)</span><br style="font-family: Arial;" /><span style="font-family: Arial;">* Bad gasoline (fuel contaminated with water or too much alcohol)</span><br style="font-family: Arial;" /><br />
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Sometimes, what feels like a hesitation is actually <b>ignition misfire</b>rather than lean misfire. The causes of ignition misfire may include:<br /><br />* Dirty or worn spark plugs<br />* Bad plug wires<br />* Weak ignition coil<br />* Wet plug wires<br /></div>
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<img alt="using scan tool to diagnose hesitation" src="http://www.aa1car.com/library/scan_tool_check.jpg" /><br /><i>A scan tool that can display sensor data and fuel trim values can help you diagnose a hesitation problem.</i></center>
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DIAGNOSE ENGINE HESITATION PROBLEM</h3>
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Diagnose may require checking the engine computer with a scan tool for any fault codes (including misfire codes), checking sensor response with a scan tool by looking at the various sensor PIDS (sensor values displayed on the scan tool), and testing sensors with a DVOM or scope if the values are out of range or the sensor is not responding normally. Additional diagnostic checks may include searching for vacuum leaks, inspecting/cleaning the EGR valve, measuring fuel pressure and volume, removing and inspecting the spark plugs, etc.</div>
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You can use a scan tool to check the fuel trim readings to see if the engine is running lean. Lean mixtures that are caused by vacuum leaks will have the most noticeable effect at idle. At part and full throttle, there is so much air entering the engine that a little extra air from a vacuum leak has a negligible effect.</div>
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Plug your scan tool into the diagnostic connector and start the engine, then look at the Short Term Fuel Trim (STFT) and Long Term Fuel Trim (LTFT) values. Normal range is typically plus or minus 8. If the numbers are +10 or higher for STFT and LTFT, the engine is running LEAN. If you rev the engine to 1500 to 2000 rpm and hold it for a minute or so, and the STFT value drops back down to a more normal reading, it confirms the engine has a vacuum leak at idle. If the STFT value does not change much, the lean fuel condition is more likely a fuel delivery problem (weak fuel pump, restricted fuel filter, dirty fuel injectors or a leaky fuel pressure regulator) than a vacuum leak.</div>
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DIAGNOSTIC TIPS FOR P0171 OR P0174 LEAN TROUBLE CODES</h3>
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A code P0171 or P0174 (or both) indicate the engine is running lean. This means there is too much air and/or not enough fuel.</div>
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If you have a scan tool that can display Short Term Fuel Trim (STFT), you can confirm the engine is running lean by looking at the STFT at idle. If STFT is greater than about 10 to 12, the engine is running LEAN. Increase engine speed to 1600 to 2000 rpm and hold for a minute or so, then recheck the STFT value. If it has dropped 3 or 4 points or more, the lean problem is due to a vacuum leak (vacuum leaks have more of an impact on the idle fuel mixture than the cruise mixture). If the STFT valve is still the same, the problem is probably sensor-related (dirty or bad MAF sensor, or bad MAP sensor), or is due to low fuel pressure. The next steps would be to use the scan tool to look at the airflow and MAP sensor readings, and to check fuel pressure.</div>
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A lean fuel condition can be caused by:<br /><br />* Low fuel pressure due to a weak pump or leaky fuel pressure regulator. (use a fuel pressure gauge to check fuel pressure at idle)<br /><br />* Dirty fuel injectors. (try cleaning the injectors)<br /><br />* Vacuum leaks at the intake manifold, vacuum hose connections or throttle body. (Check for vacuum leaks)<br /><br />* Leaky EGR valve. (Check the operation of the EGR valve)<br /><br />* Leaky PCV Valve or hose. (Check valve and hose connections)<br /><br />* Dirty or defective Mass Airflow Sensor (MAF). (Try cleaning the MAF sensor wires or filament with aerosol electronics cleaner. Do NOT use anything else to clean the sensor, and do not touch the sensor wires)<br /><br />* <b>TIP:</b> On many Fords, a P0171 and/or P0174 Lean Code may sometimes appear because of a bad Differential Pressure Sensor (DPFE). This sensor monitors EGR flow, and is located on the engine near the EGR valve. There are two hoses that connect the sensor to the tube that runs from the exhaust manifold to the EGR valve. The sensor misreads EGR flow and the computer increases EGR which has a leaning effect on the fuel mixture. The fix is to replace the DPFE sensor.</div>
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REPAIRS</h3>
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Repairs will depend on what is causing the hesitation. If the cause is fuel related, it may require cleaning the fuel injectors or fixing a vacuum leak. If the cause is ignition related, it may require replacing the spark plugs and plug wires.</div>
Anonymoushttp://www.blogger.com/profile/07884952301771193295noreply@blogger.com0tag:blogger.com,1999:blog-2529084104041640172.post-16303231471673673162017-01-09T08:20:00.002-08:002017-01-09T11:29:53.493-08:00Engine & Driveability Problems: 13 Diagnose Engine Stalling Problem<center style="font-family: arial;">
<img alt="engine stalling misfiring" src="http://www.aa1car.com/library/2005/engine_shake.gif" /><br /><h1>
Diagnose Engine Stalling Problem</h1>
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An engine that stalls repeatedly can be really annoying. So can an engine that stalls for no apparent reason while driving. Stalling problems are often temperature related and more apt to occur during cold weather or when a cold engine is first started.</div>
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<b><img src="http://www.aa1car.com/library/2005/s_yelcar.gif" /> Problem: Engine stalls when cold immediately after starting</b></div>
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This kind of stalling problem often means the engine is not getting enough fuel and/or too much air. A cold engine needs a fairly rich fuel mixture to start, and to idle smoothly while it warms up. Any of the following could cause or contribute to this kind of stalling problem:</div>
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<b>An engine vacuum leak. </b> Check for loose or broken vacuum hoses, leaks around the intake manifold gasket or throttle body, leaks around the PCV valve and EGR valve.</div>
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<b>A dirty or defective airflow sensor.</b> A sensor that has been contaminated by fuel varnish or dirt will under report airflow and be slow to react to changes in airflow. This can upset the air/fuel mixture causing idle, stalling and hesitation problems. Cleaning the airflow sensor wire with aerosol electronics cleaner can often restore normal operation and cure the problem.</div>
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<b>A defective idle speed control system.</b> Idle speed on a fuel injected engine is controlled by allowing a small amount of air to bypass the throttle. If the idle air bypass circuit is plugged with dirt or fuel varnish, or the solenoid valve is sticking or broken, the engine may not get enough air to idle normally causing it to stall. Cleaning the idle air bypass circuit in the throttle body with aerosol throttle cleaner will often remove the gunk and solve your stalling problem. If a good soaking with cleaner fails to fix the stalling problem, check the wiring connector. It might be loose or corroded. If no wiring faults are found, you may have to replace the idle speed control solenoid.</div>
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<b>A faulty coolant sensor.</b> If the coolant sensor is bad and tells the PCM the engine is colder or warmer than it really is, that can screw up the fuel mixture, too. If the coolant sensor reads colder than normal, or cold all the time, the engine will run rich. This won't cause cold stalling but it can make for a rough idle once the engine warms up, and it kills fuel economy. If the coolant sensor reads warmer than normal, or reads hot all the time, the PCM will lean out the fuel mixture too much, causing the engine to stall when it is cold. See the article on coolant sensors for how to test the sensor. Replacing a defective coolant sensor will cure this cause of stalling.</div>
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<b>A faulty air temperature sensor.</b> This sensor tells the PCM the temperature of the air entering the intake manifold. The PCM needs an accurate input so it can balance the air/fuel mixture properly. Just like a bad coolant sensor, a bad air temperature sensor can upset the fuel mixture causing stalling problems.</div>
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<b>A bad Manifold Absolute Pressure (MAP) sensor.</b> This sensor monitors intake vacuum, which the PCM uses to determine engine load. If the MAP sensor is not reading accurately, the PCM may add too much fuel or not enough, causing the engine to stall. See the article on MAP sensors for how to diagnose this sensor.</div>
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<b>Low engine compression.</b> If your engine has a lot of miles on it and compression is low because the piston rings and/or cylinders are worn, ot it has one or more leaky valves, it may not have enough oomph to keep idling. A compression check will tell you if this is a problem or not, and if it is there's no easy fix other than to overhaul or replace the engine.</div>
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<b>Worn or fouled spark plugs.</b> Ignition misfire can make any engine stall at idle. When the engine is running slowly, there is less momentum to keep it going, so a bad misfire may cause it to stall. If the spark plugs have not been changed in a long time, a new set of plugs and/or plug wires can restore a good hot spark and eliminate the misfire. A weak ignition coil or a faulty crankshaft position sensor may also cause a stalling problem.</div>
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<b>Bad gas.</b> Gasoline that contains too much alcohol (more than 10%), or gasoline that has been contaminated with water or some other substance may not burn well and cause your engine to stall. If the stalling started to occur shortly after your last fill-up, suspect bad gas. The cure is to drain the tank and refill it with fresh gas from another filling station, or just use up the bad fuel (if the engine runs okay at highway speeds), then refill at another station when the tank is near empty.</div>
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<b><img src="http://www.aa1car.com/library/2005/s_yelcar.gif" /> Problem: Engine stalls when you stop for a traffic light or when idling</b></div>
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A stop light or idle stall often means the engine is not idling fast enough (idle speed too low), or the engine is being lugged down by a load on it created by the air conditioning compressor and/or alternator. It could also mean the fuel mixture is too rich or too lean, causing the engine to run poorly. Possible causes that may contribute to this kind of stalling include:</div>
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<b>A Bad A/C compressor.</b> If the A/C compressor is binding up, possibly due to a lack of lubrication, internal wear or an over-charged A/C system (too much refrigerant), it may be lugging down the engine when it is engaged. If the problem only occurs when the A/C is on, there is an issue with the compressor.</div>
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<b>Unusually high electrical load on the charging system.</b> If the battery is run down and the alternator is working hard to recharge it, the increases load on the engine may pull down the idle rpm to the point where it causes the engine to stall. Check the battery state of charge to see if the battery is run down or failing. If the battery is low, use a battery charger to recharge it, or drive at highways speeds for half an hour or so. If the battery is failing and is not holding a charge, time to buy a new battery.</div>
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<b>NOTE:</b> Low voltage can adversely affect the operation of the ignition system and fuel injectors, causing stalling and misfiring. A good charging system should produce about 13.5 to 14.5 volts at idle.</div>
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<b><img src="http://www.aa1car.com/library/2005/s_yelcar.gif" /> Problem: Engine stalls unexpectedly while driving</b></div>
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Stalls like this are often ignition-related and happen when the engine loses spark. The underlying cause is often a bad crankshaft position sensor, or sometimes a failing ignition coil (if the engine has only one coil). A faulty ignition switch that loses contact intermittently may also cause the engine to suddenly die for no reason.</div>
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When this happens, open the hood and check for spark. This can be done by pulling off a plug wire (if the engine has plug wires), and placing the end near the block while a helper cranks the engine. DO NOT hold the wire as it may shock you if the ignition system is working. If you do not see a spark or hear the plug wire snapping when the engine is cranking, the fault is in the ignition system.</div>
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If the engine has spark, it may have died due to a loss of fuel pressure. When fuel pumps fail, they usually just quit with little or no warning. The engine usually won't restart and the vehicle has to be towed in for repairs. Listen for a buzz from the vicinity of the fuel tank when the ignition is turned on. No buzz means the fuel pump isn't running. It might just be a blown fuse or a bad relay, but on a high mileage vehicle it's often a bad fuel pump.</div>
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Another possibility is a bad PCM (engine computer) relay. The power supply to the PCM is often routed through one or two main power relays. If one of these relays loses contact momentarily, it's like pulling the plug on the PCM. The PCM shuts down and turns off the ignition and fuel injectors, causing the engine to stall. One way to see if this is a possibility is to switch or replace the PCM power relay(s). If the problem goes away, the cause was a bad relay. If it continues, the fault is something else (possible a wiring fault in the PCM relay or PCM power circuit).</div>
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Yet another possibility is low system voltage, loss of voltage, or overcharging. The PCM and other control modules require a steady 12volts to operate correctly. If the supply voltage suddenly drops below 9 volts, or surges about 16 volts, or cuts out, the PCM may temporarily kill the injectors or ignition circuit. The underlying cause may be an intermittent short somewhere in the electrical system or charging system that causes a momentary drop or surge in voltage. These can be very difficult to find, and often require hooking up a scan tool that can capture snapshot data when the stall occurs. By looking at the data, a technician can see the chain of events that caused the stall, and hopefully identify, isolate and repair the fault.</div>
Anonymoushttp://www.blogger.com/profile/07884952301771193295noreply@blogger.com0tag:blogger.com,1999:blog-2529084104041640172.post-7471355379449537992017-01-09T08:15:00.005-08:002017-01-09T08:16:23.980-08:00Engine & Driveability Problems: 12 Engine Vacuum Leaks<center style="font-family: Arial;">
<img alt="engine intake vacuum gauge reading" src="http://www.aa1car.com/library/vacuum_gauge_reading.jpg" height="250" /><br /><h1>
Engine Vacuum Leaks <iframe allowtransparency="true" frameborder="0" scrolling="no" src="http://www.facebook.com/plugins/like.php?href=http%3A%2F%2Fwww.aa1car.com%2Flibrary%2Fvacleak.htm&layout=button_count&show_faces=true&width=90&action=like&font=arial&colorscheme=light&height=21" style="border-style: none; border-width: initial; height: 21px; overflow: hidden; width: 90px;"></iframe> <iframe allowtransparency="true" class="twitter-share-button twitter-share-button-rendered twitter-tweet-button" frameborder="0" id="twitter-widget-0" scrolling="no" src="http://platform.twitter.com/widgets/tweet_button.3748f7cda49448f6c6f7854238570ba0.en.html#dnt=false&id=twitter-widget-0&lang=en&original_referer=http%3A%2F%2Fwww.aa1car.com%2Flibrary%2Fvacleak.htm&size=m&text=Engine%20Vacuum%20Leaks&time=1483978415822&type=share&url=http%3A%2F%2Fwww.aa1car.com%2Flibrary%2Fvacleak.htm" style="height: 20px; position: static; visibility: visible; width: 60px;" title="Twitter Tweet Button"></iframe></h1>
<b>Copyright AA1Car</b></center>
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Have you ever tried to tune an engine only to find it won't idle or run right? Or have you ever been confronted with an engine that just doesn't seem to run right no matter what you've done or replaced? You may be dealing with an engine <b>vacuum leak.</b></div>
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Sometimes a vacuum leak will whistle or hiss and make itself obvious. But oftentimes, a vacuum leak will disguise itself as an ignition or fuel problem that defies diagnosis. Either way, an engine vacuum leak is bad news because allows "unmetered" <span class="IL_AD" id="IL_AD4" style="background-attachment: scroll; background-image: none; background-repeat: repeat; border-bottom: 1px solid rgb(27 , 142 , 222); color: rgb(27 , 142 , 222); cursor: pointer; display: inline; float: none; font-size: 16px; padding: 0px 0px 1px; position: static; text-decoration: underline;">air</span> to enter the engine and upset the air/fuel ratio.</div>
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So how do you know when a vacuum leak is causing a problem? If the engine is experiencing any of the following symptoms, a vacuum leak is probably responsible:</div>
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<li><b>Too fast an idle speed</b>. If an engine without computerized idle speed control is idling too fast and refuses to come down to a normal idle speed despite your best efforts to back off the <a href="http://www.aa1car.com/library/carburetor.htm">carburetor</a> idle speed screw or air bypass adjustment screw (fuel injection), air is getting past the throttle somewhere. Common leak paths include the carburetor and throttle body gaskets, carburetor insulator spacers, intake manifold gaskets, and of course, any of the engine's vacuum fittings, hoses and accessories. It is even possible that leaky O-rings around the fuel injectors are allowing air to leak past the seals. Another overlooked item can be a worn throttle shaft.</li>
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<li><b>A rough idle or stalling</b>. A performance cam with lots of valve overlap can give an engine a lopping idle, but so can a vacuum leak. A really serious leak can lean the air/fuel mixture out to such an extent that an engine won't idle at all. An <a href="http://www.aa1car.com/library/egr.htm">EGR valve </a>that is stuck open at idle can have the same effect as a vacuum leak. So too can the wrong PCV valve (one that flows too much air for the <span class="IL_AD" id="IL_AD2" style="background-attachment: scroll; background-image: none; background-repeat: repeat; border-bottom: 1px solid rgb(27 , 142 , 222); color: rgb(27 , 142 , 222); cursor: pointer; display: inline; float: none; font-size: 16px; padding: 0px 0px 1px; position: static; text-decoration: underline;">application</span>), or a loose PCV hose. The rough idle in these cases is caused by "lean misfire." The fuel mixture is too lean to ignite reliably so it often misfires and fails to ignite at all. Lean misfire will show up as elevated hydrocarbon (HC) readings in the exhaust, enough, in fact, to cause a vehicle to fail an emissions test.</li>
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<li><b>Hesitation or misfiring when accelerating</b>. This may be due to a vacuum leak, but it can also be caused by a weak or inoperative <span class="IL_AD" id="IL_AD3" style="background-attachment: scroll; background-image: none; background-repeat: repeat; border-bottom: 1px solid rgb(27 , 142 , 222); color: rgb(27 , 142 , 222); cursor: pointer; display: inline; float: none; font-size: 16px; padding: 0px 0px 1px; position: static; text-decoration: underline;">accelerator</span> pump in a carburetor, dirty injectors, or even ignition problems such as a cracked coil, worn spark plugs or incorrectly gapped plugs.</li>
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<li><b>An idle mixture that defies adjustment.</b> When setting the idle mixture adjustment screws on a carburetor, the idle speed should start to falter as the adjustment screws are turned in to lean out the mixture. If the screws seem to have little or no effect on idle, you have either got a carburetor problem or a vacuum leak.</li>
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The important thing to keep in mind about vacuum leaks is that they have the most noticeable effect at idle. At part and full throttle, there is so much air entering the engine that a little extra air from a vacuum leak has a negligible effect.</div>
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<b>TIP:</b> If you have a scan tool, look at the Short Term Fuel Trim (STFT) and Long Term Fuel Trim (LTFT) values. Normal range is plus or minus 8. If the numbers are +10 or higher for STFT and LTFT, the engine is running LEAN. If you rev the engine to 1500 to 2000 rpm and hold it for a minute or so, and the STFT value drops back down to a more normal reading, it confirms the engine has a vacuum leak at idle. If the STFT value does not change much, the lean fuel condition is more likely a fuel delivery problem (weak fuel pump, restricted fuel filter, dirty fuel injectors or a leaky fuel pressure regulator) than a vacuum leak.</div>
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For more information about using fuel trim to diagnose a lean fuel condition, see <a href="http://www.aa1car.com/library/what_is_fuel_trim.htm">What Is Fuel Trim?</a>, or view this article on <a href="http://www.aa1car.com/library/fuel_trim_wellsmfg.pdf">Fuel Trim by Wells Manufacturing</a> (<span class="IL_AD" id="IL_AD1" style="background-attachment: scroll; background-image: none; background-repeat: repeat; border-bottom: 1px solid rgb(27 , 142 , 222); color: rgb(27 , 142 , 222); cursor: pointer; display: inline; float: none; font-size: 16px; padding: 0px 0px 1px; position: static; text-decoration: underline;">PDF file</span>).</div>
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Before we get into the various techniques of finding and fixing vacuum leaks, let's quickly review vacuum's role in fuel delivery.</div>
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WHAT IS INTAKE VACUUM?</h3>
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<b>Intake vacuum</b> exists in the intake manifold as a result of the pumping action of the engine's pistons and the restriction created by the throttle valve. Were it not for the throttle choking off the flow of air into the engine, there would be little if any vacuum in the intake manifold (like a diesel). The downside of intake vacuum is that it creates pumping losses and reduces engine efficiency.</div>
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On older carbureted engines, vacuum is needed to pull fuel into the engine. Vacuum siphons fuel through the idle, main metering and power circuits. An engine with a vacuum leak, therefore, will likely be an engine that suffers from the symptoms of lean carburetion such as lean misfire, hesitation, stalling and rough idle. But the same symptoms can also be caused by a clogged catalytic converter or other exhaust restriction, a leaky EGR valve or valve timing problems (all of which reduce intake vacuum).</div>
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Engines with Multiport Fuel Injection and Gasoline Direct Injection don't need vacuum to pull fuel into the engine because it is sprayed in under pressure. Even so, most of these engines still have a throttle for regulating airflow and engine speed. And like the older carbureted engines, a throttle body also creates an airflow restriction that creates vacuum inside the intake manifold.</div>
<ins id="aswift_1_expand" style="border: none; display: inline-table; font-family: Arial; height: 250px; margin: 0px; padding: 0px; position: relative; visibility: visible; width: 300px;"><ins id="aswift_1_anchor" style="border: none; display: block; height: 250px; margin: 0px; padding: 0px; position: relative; visibility: visible; width: 300px;"><iframe allowfullscreen="true" allowtransparency="true" frameborder="0" height="250" hspace="0" id="aswift_1" marginheight="0" marginwidth="0" name="aswift_1" scrolling="no" style="left: 0px; position: absolute; top: 0px;" vspace="0" width="300"></iframe></ins></ins><br style="font-family: Arial;" />
<br />
<div style="font-family: Arial;">
On most engines, intake vacuum should be steady between 16 and 22 inches Hg (Mercury). A lower reading usually indicates a vacuum leak, or one of the other problems just mentioned. A reading that gradually drops while the engine is idling almost always points to an exhaust restriction. An oscillating vacuum reading usually indicates a leaky valve or badly worn valve guides that leak vacuum.</div>
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Although fuel injected engines do not rely on intake vacuum to pull fuelinto the engine, vacuum leaks can upset the carefully balanced air/fuel ratio by allowing "unmetered" air to enter the engine. The result is the same kind of driveability symptoms as a vacuum leak on a carbureted engine (<a href="http://www.aa1car.com/random-misfire/">lean misfire</a>, <a href="http://www.aa1car.com/library/problem_hesitation.htm">hesitation when accelerating</a>, rough idle and possibly even stalling). Common leak points include injector O-rings, intake manifold gaskets, idle air control circuit and the throttle shaft.</div>
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Fuel injected engines also rely on intake vacuum to regulate the fuel pressure behind the injectors. Fuel delivery cannot be accurately metered unless a fairly constant pressure differential is maintained. So the fuel pressure regulator diaphragm is connected to a source of intake vacuum. Vacuum working against a spring-loaded diaphragm inside the regulator opens a bypass that shunts fuel back to the tank through a return line. This causes the fuel pressure in the injector rail to rise when engine load increases (and vacuum drops). Thus, the regulator uses vacuum to maintain fuel pressure and the correct air/fuel ratio. A vacuum leak changes the equation by causing a drop in vacuum and a corresponding increase in line pressure.</div>
<h3 style="font-family: Arial;">
MEASURING INTAKE VACUUM</h3>
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Vacuum is measured with a vacuum gauge. Most are calibrated in inches Hg (Mercury), but you may also see some gauges that are also calibrated in inches of H20 (water) or kilopascals (kPa) or even bars. One inch of vacuum measured in inches Hg equals 13.570 inches in H20, 0.4898 psi (pounds per square inch) or 3.377 kPa.</div>
<div style="font-family: Arial;">
Here's a conversion table you can use to convert units of measurement:</div>
<center style="font-family: Arial;">
<form name="cat=Pressure" style="margin: 0px; padding: 0px;">
<table align="center" border="0" cellpadding="0" cellspacing="0" style="font-family: Verdana; font-size: 16px; width: 500px;"><tbody>
<tr><td style="font-size: 13px; padding: 1.2ex 1.5ex; width: 228.75px;">From:<br />
<input name="bindid=left;base=1" style="font-family: Verdana; font-size: 13px; width: 230px;" type="text" /></td><td style="font-size: 13px; padding: 1.2ex 1.5ex; width: 228.75px;">To:<br />
<input name="bindid=right" style="font-family: Verdana; font-size: 13px; width: 230px;" type="text" /></td></tr>
<tr><td style="font-size: 13px; padding: 1.2ex 1.5ex; width: 228.75px;"><select name="left" size="10" style="font-family: Verdana; font-size: 13px; width: 230px;"><option selected="" value="kilopascal">kilopascal [kPa]</option><option value="newton/square meter">newton/square meter</option><option value="newton/square centimeter">newton/square centimeter</option><option value="newton/square millimeter">newton/square millimeter</option><option value="bar">bar</option><option value="millibar">millibar [mbar]</option><option value="microbar">microbar [µbar]</option><option value="psi">psi [psi]</option><option value="inch mercury (60%b0F)">inch mercury (60°F) [inHg]</option><option value="inch water (60%b0F)">inch water (60°F) [inAq]</option></select></td><td style="font-size: 13px; padding: 1.2ex 1.5ex; width: 228.75px;"><select name="right" size="10" style="font-family: Verdana; font-size: 13px; width: 230px;"><option selected="" value="kilopascal">kilopascal [kPa]</option><option value="newton/square meter">newton/square meter</option><option value="newton/square centimeter">newton/square centimeter</option><option value="newton/square millimeter">newton/square millimeter</option><option value="bar">bar</option><option value="millibar">millibar [mbar]</option><option value="microbar">microbar [µbar]</option><option value="psi">psi [psi]</option><option value="inch mercury (60%b0F)">inch mercury (60°F) [inHg]</option><option value="inch water (60%b0F)">inch water (60°F) [inAq]</option></select></td></tr>
<tr><td colspan="2" style="font-size: 13px; padding: 1.2ex 1.5ex;">Result:<br />
<input name="type=result;bindid=left;bindid2=right" style="font-family: Verdana; font-size: 13px; width: 480px;" type="text" /></td></tr>
<tr><td colspan="2" style="font-size: 13px; padding: 1.2ex 1.5ex; text-align: center;"><a href="http://www.unitconversion.org/unit_converter/pressure.html">pressure conversion</a> factors provided by unitconversion.org</td></tr>
</tbody></table>
</form>
</center>
<h3 style="font-family: Arial;">
ENGINE VACUUM LEAK DETECTION</h3>
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Okay, now that we have covered what a vacuum leaks do, how do you find components that leak vacuum? One way is to visually inspect all the vacuum hoses and connections. Look for disconnected, loose or cracked hoses, broken fittings, etc. Hey, you might get lucky and find the problem in a few minutes, or you might waste half the day trying to find the mysterious leak. Vacuum leaks are often the elusive needle in a haystack. And if it is not a hose leaking vacuum but something else such as a gasket, worn throttle shaft, injector O-rings, etc., you may never find it using this technique.</div>
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A faster technique for finding intake manifold vacuum leaks is to get a bottle of propane and attach a length of rubber hose to the gas valve. Open the valve so you have a steady flow of gas. Then hold the hose near suspected leak points while the engine is idling. If there is a leak, propane will be siphoned in through the leak. The resulting "correction" in the engine's air/fuel ratio should cause a noticeable change in idle speed and/or smoothness (Note: on engines with computerized idle speed control, disconnect the idle speed control motor first).</div>
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Aerosol carburetor cleaner can also be used the same way. <b>CAUTION:</b> Solvent is extremely flammable, so do not smoke or use it if there are any sparks in the vicinity (arcing plug wires, for example). Spray the solvent on suspected leak points while the engine is idling. If there is a leak, the solvent will be drawn into the engine and have the same effect as the propane. The idle speed will suddenly change and smooth out.</div>
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<b>TIP:</b> If you have a scan tool, look at the Short Term Fuel Trim (STFT) value while you are using carb cleaner or propane to check suspected vacuum leak points. If there is a leak and some of the cleaner or propane is sucked in through the leak, you will see a momentary drop in the STFT reading. This confirms you have found a leak (keep checking because there may be multiple leaks!).</div>
<center style="font-family: Arial;">
<img alt="smoke leak detection machine" src="http://www.aa1car.com/library/elements/smoke_pro_smoke_machine" /><br /><i>A smoke machine with UV dye can reveal tiny vacuum leaks.<br />Low pressure smoke is fed into the intake manifold, then you look for the telltale dye to find the leak.</i></center>
<h3 style="font-family: Arial;">
USING A SMOKE MACHINE TO FIND ENGINE VACUUM LEAKS</h3>
<div style="font-family: Arial;">
A much safer technique is to use a smoke machine. These machines feed artificial smoke into the intake manifold, The smoke may also be mixed with an ultraviolet dye to make leaks easier to see. You then look for smoke seeping out of hoses, gaskets or cracks in the manifold and/or use a UV light to find the leak. This type of equipment is often needed to find small air leaks in the EVAP (evaporative emissions) control system. Smoke machines can cost $600 to $2000 or more depending on the model and features, so they are primarily for use by professional technicians.</div>
<h3 style="font-family: Arial;">
FINDING LEAKS WITH AN EXHAUST ANALYZER</h3>
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Propane can also be used in conjunction with an exhaust analyzer (do NOT use carburetor cleaner or you may damage your analyzer!). Engine vacuum leaks almost always cause fluctuating HC readings, so an infrared exhaust analyzer can (1) tell you if there is indeed a leak, and (2) where the leak is using the propane procedure.</div>
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Two types of vacuum leaks can be diagnosed with an analyzer. The first kind is a general vacuum leak (PCV hose, brake booster, etc.) that leans out the mixture and causes a very low CO reading and only a slightly higher fluctuating HC reading. The O2 reading will also be high. The second kind of vacuum leak is a "point" leak that affects only one or two cylinders (a leaky manifold gasket or a crack or porosity leak in one of the manifold runners). This will be indicated by a normal or low CO reading combined with high fluctuating HC readings. O2 will again be high.</div>
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To find a leak, feed propane at suspected leak points until you note an improvement in idle quality and/or a change in the HC/CO/O2 readings. When you have found the leak, the idle should smooth out, HC and O2 should drop and CO rise.</div>
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It is important to note that an overly lean idle mixture will also cause a fluctuating HC reading the same as a vacuum leak. To tell one from the other, there is a simple "trick" you can use. Momentarily enrich the idle mixture to 1.5 to 2.0% CO by placing a clean shop rag over the top of the carburetor. If the engine smooths out and HC drops and remains stable, the problem is a lean idle mixture adjustment. If HC still fluctuates, however, the engine is still too lean in one or more cylinders indicating a vacuum leak.</div>
<h3 style="font-family: Arial;">
ELECTRONIC VACUUM LEAK DETECTION</h3>
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If you like gadgets, there are electronic tools designed to detect vacuum leaks. An electronic vacuum leak detector will beep or flash when it detects ultrasonic vibrations that are characteristic of a vacuum leak. These tools use a sensitive microphone to listen for certain noise frequencies. Though extremely sensitive, these tools sometimes react to tiny leaks that are not really causing a problem, or "false" leaks such as the noise created by arcing inside the distributor cap or normal bearing noise in the alternator.</div>
<h3 style="font-family: Arial;">
PRESSURE VACUUM LEAK DETECTION TECHNIQUES</h3>
<div style="font-family: Arial;">
Another way to find an elusive vacuum leak is to pressurize the intake manifold with about three lbs. of regulated air. This can be done by attaching a regulator to your shop air hose, then attaching the hose to a vacuum fitting or the PCV valve fitting on the intake manifold, carburetor or throttle body. Do not apply too much pressure or you may create new leaks! With the engine off and air flowing into the manifold, spray soapy water on suspected leaks. If you see bubbles, you have found the leak.</div>
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You can also use the opposite technique, which is to apply vacuum with a hand-pump to various vacuum hoses and circuits to see if they hold vacuum. But this technique means tracing the entire circuit to see where it ends, and disconnecting and plugging any parts of the circuit that do not "dead end" against a diaphragm or valve.</div>
<h3 style="font-family: Arial;">
HOW TO REPAIR AN ENGINE VACUUM LEAK</h3>
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Okay, now you have found the leak. Here are some suggestions on how to fix it:</div>
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<b><br /></b></div>
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<b>Leaky vacuum hoses</b> Replace them. If the end of a hose is loose or cracked, cutting it off and sticking it back on may temporarily eliminate the leak. But if the hose is rotten or age hardened, it needs to be replaced. Shortening hoses may also create additional problems. The hose may chaff or rub against other components, or pull loose as a result of engine motion and vibration. Use the correct type of replacement hose (PVC hose or vacuum hose capable of withstanding fuel vapors and vacuum without collapsing). Also, be sure the replacement hose is the same diameter and length as the original.</div>
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<b><br /></b></div>
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<b>Carburetor or throttle body base gasket vacuum leaks</b> Try tightening down the carburetor or throttle body mounting bolts. If that doesn't stop the leak, replace the gasket under the carburetor or throttle body. If there is a heat insulator or adapter plate under the unit, it may also have to be replaced depending on its condition. While the carburetor or throttle body is off, use a straightedge to check the base for flatness (and the manifold, too). Warped surfaces can prevent a tight seal, so if you find any it calls for resurfacing or component replacement.</div>
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<b><br /></b></div>
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<b>Carburetor or throttle body throttle shaft vacuum leaks</b> Wear here can only be repaired by resleeving the throttle shaft, which for all practical purposes means replacing the carburetor or throttle body with a new or remanufactured unit.</div>
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<b><br /></b></div>
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<b>Intake manifold gasket vacuum leaks</b> Try re torquing the intake manifold bolts, working from the center out in the recommended tightening sequence. If that fails, the intake manifold will have to be removed and the intake gaskets replaced. Sometimes the mating surface of the intake manifold or the heads will not be flat (check both with a straightedge). If warped, the intake manifold and/or heads will have to be resurfaced on a milling machine. Another problem to watch out for here are heads that have been milled or resurfaced to raise compression. To maintain proper alignment between the manifold and heads, metal also needs to be machined off the bottom of the manifold where it mates with the block, otherwise it will sit to high and the ports and bolt holes won't align.</div>
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<b><br /></b></div>
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<b>EGR valve leaks</b> If the valve isn't closing all the way due to carbon deposits on the stem or valve seat, cleaning may be all that is needed to cure the problem. Otherwise, the engine will need a new EGR valve.</div>
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<b><br /></b></div>
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<b>Leaky power brake booster</b> Replace it. But first make sure it is the booster and not just the hose or check valve that is leaking.</div>
Anonymoushttp://www.blogger.com/profile/07884952301771193295noreply@blogger.com0tag:blogger.com,1999:blog-2529084104041640172.post-8757933113561084092017-01-09T08:12:00.002-08:002017-01-09T08:12:43.628-08:00 Engine & Driveability Problems: 11 Engine Idle Surge<center style="font-family: Arial;">
<br /><img alt="idle surge caused by dirty idle speed control valve" src="http://www.aa1car.com/library/throttle_open.jpg" /><br /><h1>
Idle Surge</h1>
</center>
<div style="font-family: Arial;">
If a vehicle idles erratically and surges (idle speed is not steady and increases and decreases), the problem may be a buildup of carbon or fuel varnish deposits in the idle speed control valve (also called the idle air control valve or IAC valve). The cure for this condition is to clean the valve with some aerosol throttle cleaner or engine top cleaner.</div>
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<div style="font-family: Arial;">
Here's how to clean the IAC valve:</div>
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Disconnect the air intake ductwork from the throttle body.</div>
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Start the engine, then increase and hold the idle speed to 1,000 to 1,500 rpm.</div>
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Spray the throttle cleaner or engine cleaner into the throat of the throttle body, aiming for the idle air bypass port (usually located on the side or top of the throttle body opening). Give this area a good dose of cleaner (about 10 second's worth).</div>
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Turn the engine off to allow the cleaner to soak into the IAC passageway.</div>
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Wait about three minutes.</div>
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Restart the engine, rev and hold at 1,000 to 1,500 rpm, and repeat the cleaning process again.</div>
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Turn the engine off again, and reattach the air intake duct work to the throttle body.</div>
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Start the engine and rev and hold to 1,500 to 2,000 rpm until no white smoke is coming out of the exhaust pipe.</div>
<center style="font-family: Arial;">
<img alt="Ford idle air speed control valve" src="http://www.aa1car.com/library/iac_valve_ford.jpg" /><br /><i>Cleaning the Idle Air Speed Control Valve with aerosol throttle cleaner can often solve an idle problem.</i></center>
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If this fails to make any difference, you can remove the IAC valve from the throttle body and spray cleaner directly on the tip of the valve and/or into the ports in the throttle body. Let the cleaner soak awhile, repeat as needed, then reinstall the IAC valve, start the engine and run it at 1,500 to 2,000 rpm as before until no white smoke is seen in the exahust.</div>
<div style="font-family: Arial;">
If the idle speed still surges after this, the IAC valve is defective and needs to be replaced.</div>
<center style="font-family: Arial;">
<img alt="new Ford IAC idle speed control valve" src="http://www.aa1car.com/library/iac_valve_new.jpg" /><br /><i>If the old Idle Speed Control Valve fails to respond to cleaning, replace it with a new one.</i></center>
Anonymoushttp://www.blogger.com/profile/07884952301771193295noreply@blogger.com0tag:blogger.com,1999:blog-2529084104041640172.post-631065703067205012017-01-09T08:06:00.003-08:002017-01-09T08:06:38.669-08:00Engine & Driveability Problems: 10 Engine Won't Start: No Spark<center style="font-family: Arial;">
<h1>
Engine Won't Start: No Spark</h1>
</center>
<div style="font-family: Arial;">
If your engine cranks normally but will not start because it has no spark, or it stalls and won't restart because it has no spark, the problem may be due to any of the following:</div>
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<div style="font-family: Arial;">
* A bad crankshaft position (CKP) sensor (on engines that do not have a distributor), or broken, loose or corroded wires from the sensor to the PCM.</div>
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* A bad ignition module (on engines that have a distributor or use an ignition module separate from the PCM)</div>
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* A bad pickup inside the distributor (on engines that have a distributor), a stripped distributor drive gear (common problem with plastic distributor drive gears), broken, loose or corroded wires from the pickup to the ignition module or PCM.</div>
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* A bad ignition coil (on engines that have a distributor and a single coil)</div>
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* A bad rotor or distributor cap (cracks or carbon tracks that are allowing the spark to short to ground)</div>
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* Faulty ignition switch.</div>
<h3 style="font-family: Arial;">
HOW TO CHECK FOR SPARK</h3>
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To confirm your engine is not starting because it has no spark, you can do any of the following to check for spark:</div>
<div style="font-family: Arial;">
<b>CAUTION:</b> Secondary ignition voltage can shock you. Do NOT hold or touch a spark plug wire while cranking the engine.</div>
<center style="font-family: Arial;">
<img alt="spark plug firing" src="http://www.aa1car.com/library/spark_plug_firing.gif" /><br /><i>If your ignition system is working, you should see a strong hot spark at the spark plugs when the engine is cranked.</i></center>
<div style="font-family: Arial;">
If your engine has spark plug wires, disconnect one of the plug wires from a spark plug and place the end of the wire near a metal surface on the engine. You can insert a small Phillips screwdriver into the end of the wire (the plug boot), or a small bolt or nail to provide a conductive path. Then crank the engine and look for a spark to jump from the screwdriver, bolt or nail in the end of the plug wire to the engine. If you do not see a spark, there is an ignition problem.</div>
<div style="font-family: Arial;">
Remove a plug wire and insert an old spark plug or a spark plug tester into the end of the wire (the plug boot). Place the spark plug on a metal surface on the engine, or ground the spark plug tester to the engine. Then crank the engine to check for a spark. No spark indicates an ignition problem.</div>
<div style="font-family: Arial;">
If an engine has a coil-on-plug ignition system with no plug wires, remove one of the coils from the spark plug and insert an old spark plug, a spark plug tester or a screwdriver into the end of the coil. Ground the spark plug or plug tester to the engine, then crank the engine and look for a spark. No spark indicates an ignition problem.</div>
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Spray some aerosol starting fluid into the throttle (<b>CAUTION:</b> Starting Fluid is Extremely Flammable!). Then crank the engine. If the engine starts, you do NOT have an ignition problem. The no-start is fuel related.</div>
<center style="font-family: Arial;">
<img alt="typical distributor ignition system" src="http://www.aa1car.com/library/ignition_system1.gif" /> </center>
<h3 style="font-family: Arial;">
NO-SPARK DIAGNOSIS</h3>
<div style="font-family: Arial;">
If the engine has no spark, check for voltage at the coil positive terminal when the ignition key is on.</div>
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If there is voltage, the problem is on the trigger side of the coil (pickup, crank sensor, ignition module or primary wiring circuit).</div>
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If there is NO voltage at the coil, the problem is on the supply side (the ignition switch or ignition wiring circuit).</div>
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If the coil has voltage, the problem may be a bad high voltage output wire from the coil to the distributor, hairline cracks in the coil output tower, or cracks or carbon tracks inside the distributor cap or on the rotor.</div>
<div style="font-family: Arial;">
<br /></div>
<img alt="distributor cap" height="250" src="http://www.aa1car.com/library/distcap1.gif" style="font-family: Arial;" /><br style="font-family: Arial;" /><br />
<h3 style="font-family: Arial;">
SCAN TOOL IGNITION DIAGNOSIS</h3>
<div style="font-family: Arial;">
If you have a scan tool, plug it into the vehicle diagnostic connector and look for an rpm signal when cranking the engine. No signal? The problem is either a bad distributor pickup (on engines with a distributor), a stripped distributor drive gear (common with plastic gears), a bad crankshaft position sensor (on engines without a distributor), a wiring fault (broken or shorted wire, or a loose or corroded wiring connector).</div>
<div style="font-family: Arial;">
If the Check Engine Light is on, use a scan tool to check for ignition-related fault codes. Any coil-related codes (P0351 to P0358) would require testing the coil(s). Misfire codes would tell you the spark plugs and/or plug wires need to be checked.</div>
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<h3 style="font-family: Arial;">
IGNITION COIL CHECKS</h3>
<div style="font-family: Arial;">
The ignition coils in DIS ignition systems function the same as those in ordinary ignition systems, so testing is essentially the same. But the driveability symptoms caused by a weak coil or dead coil will be limited to one or two cylinders in a DIS ignition system with a bad coil rather than all the cylinders on an engine with a distributor and single coil.</div>
<div style="font-family: Arial;">
<i><br /></i></div>
<div style="font-family: Arial;">
<i>Most DIS no start problems are caused by a bad crank position sensor.</i></div>
<div style="font-family: Arial;">
Many DIS systems use the "waste spark" setup where one coil fires a pair of spark plugs that are opposite one another in the firing order. Others, including the newer coil-over-plug systems, have a separate coil for each spark plug.</div>
<div style="font-family: Arial;">
Individual DIS coils are tested in essentially the same way as epoxy-filled (square-type) ignition coils. First, isolate the coil pack by disconnecting all the leads. Set the ohmmeter in the low range, and recalibrate if necessary. Connect the ohmmeter leads across the ignition coil primary terminals, and compare the primary resistance reading to specifications (typically less than 2 ohms). Then connect the ohmmeter leads across the coil secondary terminals and compare the secondary resistance reading to specifications (typically 6,000-30,000 ohms). If readings are outside the specified range, the coil is defective and needs to be replaced.</div>
<div style="font-family: Arial;">
If measuring the secondary resistance of a DIS coil is difficult because of the coils location, try removing the wires from the spark plugs and measure secondary resistance through the plug wires rather than at the secondary terminals on the coils. Just remember to add in a maximum of 8,000 ohms of resistance per foot for the plug wires.</div>
<h3 style="font-family: Arial;">
DIS MODULE & SENSOR CHECKS</h3>
<div style="font-family: Arial;">
Here is a little trick that will literally show you if a DIS ignition module and its crankshaft sensor circuit are working: connect a halogen headlamp to the spade terminals that mate the DIS module to the coils. A headlamp is recommended here because it puts more of a load on the module than a test lamp. If the headlamp flashes when the engine is cranked, the DIS module and crankshaft position sensor circuit are functioning. Therefore, the problem is in the coils.</div>
<div style="font-family: Arial;">
If the headlamp does not flash, or there is no voltage to the module or coil pack when the engine is cranked, the problem is most likely in the crankshaft sensor circuit. On most vehicles, a bad crank position sensor will usually set a fault code, so use a scan tool to check for a code. Or, check the crank sensor itself.</div>
<div style="font-family: Arial;">
Magnetic crank sensors can be tested by unplugging the electrical connector and checking resistance between the appropriate terminals. If resistance is not within specs, the sensor is bad and needs to be replaced.</div>
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<br /></div>
<div style="font-family: Arial;">
Magnetic crank position sensors produce an altering current when the engine is cranked so a voltage output check is another test that can be performed. With the sensor connected, read the output voltage across the appropriate module terminals while cranking the engine. If you see at least 20 mV on the AC scale, the sensor is good, meaning the fault is probably in the module. If the output voltage is low, remove the sensor and inspect the end of it for rust or debris (magnetic sensors will attract iron and steel particles). Clean the sensor, reinstall it and test again. Make sure it has the proper air gap (if adjustable) because the spacing between the end of the sensor and the reluctor wheel or notches in the crankshaft will affect sensor output voltage. If the air gap is correct and output is still low, replace the sensor.</div>
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<br /></div>
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Hall effect crankshaft position sensors typically have three terminals; one for current feed, one for ground and one for the output signal. The sensor must have voltage and ground to produce a signal, so check these terminals first with an analog voltmeter. Sensor output can be checked by unplugging the DIS module and cranking the engine to see if the sensor produces a voltage signal. The voltmeter needle should jump each time a shutter blade passes through the Hall effect switch. If observed on an oscilloscope, you should see a square waveform. No signal would tell you the sensor has failed.</div>
<br style="font-family: Arial;" />Anonymoushttp://www.blogger.com/profile/07884952301771193295noreply@blogger.com0tag:blogger.com,1999:blog-2529084104041640172.post-22410191188981038562017-01-09T08:02:00.003-08:002017-01-09T08:08:24.342-08:00Engine & Driveability Problems: Engine Idles Rough or Misfires: 9 Diagnose Engine Misfire<center style="font-family: Arial;">
<img alt="misfiring spark plug" src="http://www.aa1car.com/library/sparks.jpg" /><br /><h1>
Diagnose Engine Misfire</h1>
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Misfire is a common driveability problem that may or may not be easy to diagnose, depending on the cause. A misfiring cylinder in a four-cylinder engine is, pardon the pun, hard to miss. The loss of 25% of the engine's power output is the equivalent of a horse trying to run on three legs. The engine may shake so badly at idle that it causes vibrations that can be felt in the steering wheel and throughout the vehicle. The engine also may be hard to start and may even stall at idle, depending on the accessory load (air conditioning, headlights and electric rear defroster, for example).</div>
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When misfire occurs, performance suffers along with fuel economy, emissions and idle quality. And, when a misfiring vehicle is subjected to an emissions test, it will usually fail because of the unusually high levels of hydrocarbons (HC) in the exhaust.</div>
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ENGINE MISFIRE CODES</h3>
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The Onboard Diagnostic (OBD II) system on 1996 and newer vehicles monitors misfires and will set a Diagnostic Trouble Code (DTC) if the misfire rate exceeds a certain value that may cause emissions to increase. In cases of severe misfire, the Check Engine light may illuminate or flash while the engine is misfiring. The codes can be read by plugging a scan tool into your vehicle's diagnostic connector located under the dash near the steering column.</div>
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The last two digits in the misfire code will tell you which cylinder or cylinders are misfiring. The digits correspond to the cylinder number in the engine's firing order:<br />
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<b>P0300....Random Misfire Code (multiple cylinders involved)<br />P0301....Cylinder 1 Misfire Detected<br />P0302....Cylinder 2 Misfire Detected<br />P0303....Cylinder 3 Misfire Detected<br />P0304....Cylinder 4 Misfire Detected<br />P0305....Cylinder 5 Misfire Detected<br />P0306....Cylinder 6 Misfire Detected<br />P0307....Cylinder 7 Misfire Detected<br />P0308....Cylinder 8 Misfire Detected<br />P0309....Cylinder 9 Misfire Detected<br />P0310....Cylinder 10 Misfire Detected<br />P0311....Cylinder 11 Misfire Detected<br />P0312....Cylinder 12 Misfire Detected</b></div>
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CAUSES OF ENGINE MISFIRE</h3>
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What causes a cylinder to misfire? Basically, it's one of three things: loss of spark; the air/fuel mixture is too far out of balance to ignite; or loss of compression. Loss of spark includes anything that prevents coil voltage from jumping the electrode gap at the end of the spark plug. Causes include worn, fouled or damaged spark plugs, bad spark plug wires or even a cracked distributor cap. A weak coil or excessive rotor gas inside a distributor would affect all cylinders, not just a single cylinder.</div>
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<img alt="spark plug firing" src="http://www.aa1car.com/library/spark_plug_firing.gif" /><br /><i>Spark plug fouling is a common cause of ignition-related misfires.</i></center>
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"Lean misfire" can occur when the air/fuel mixture is too lean (not enough gasoline in the mixture) to burn. This can be caused by a dirty, clogged or inoperative fuel injector; air leaks; or low fuel pressure because of a weak pump, restricted filter or leaky pressure regulator. Low fuel pressure would affect all cylinders rather than an individual cylinder, as would most air leaks. A leaky EGR valve can also have the same effect as an air leak. In fact, if a vehicle has one or more misfire codes and a P0401 EGR code, the fault is likely carbon buildup under the EGR valve.</div>
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Loss of compression means the cylinder loses most of its air/fuel mixture before it can be ignited. The most likely causes here are a leaky (burned) exhaust valve or a blown head gasket. If two adjacent cylinders are misfiring, it's likely the head gasket between them has failed. Also, if an engine is overheating or losing coolant, it's likely the head gasket is the culprit.</div>
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Intermittent misfires are the worst kind to diagnose because the misfire comes and goes depending on engine load or operating conditions. They seem to occur for no apparent reason. The engine may only misfire and run rough when cold but then smooth out as it warms up. Or, it may start and idle fine but then misfire or hesitate when it comes under load. Also, it may run fine most of the time but suddenly misfire or cut out for no apparent reason.</div>
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<img src="http://www.aa1car.com/library/engine_shake.gif" /><br /><i>Engine misfire can be felt at idle as a shaking or vibration.<br />At higher engine speeds, the engine may cutout, stumble or lose power.</i></center>
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MISFIRE DIAGNOSIS WITH A SCAN TOOL</h3>
<span style="font-family: "arial";">If you find one or more misfire codes when you check</span><span style="font-family: "arial";"> for fault codes with a scan tool, the codes by themselves do NOT tell you WHY the cylinder is misfiring. It could be ignition, compression or fuel related. However, if you find a P0304 misfire code for cylinder number 4, and also a P0204 code (P0200 series codes cover the injectors), you'd know the misfire was probably caused by a bad injector.</span><br />
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If there are any EGR codes (P0401 for example), the misfire could be due to carbon buildup under the EGR valve.</div>
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If there is a lean code (P0171 or P0174), the problem could be a dirty fuel injector.</div>
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If there are no other codes except for the misfire code, check the ignition components for that cylinder. The cause could be a badly worn or fouled spark plug, a bad plug wire, carbon tracking or moisture inside the boot of a coil-on-plug ignition coil, or a weak or defective coil in a multi-coil distributorless ignition system.</div>
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If you find a P0300 random misfire code, it means the misfire is random and is moving around from cylinder to cylinder. The cause here would likely be something that upsets the engine's air/fuel mixture, such as a major vacuum leak, a leaky EGR valve or unusually low fuel pressure (weak pump or faulty pressure regulator).</div>
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If your engine seems to be misfiring, but there are NO codes set (no individual cylinder misfire codes or no random misfire code), and you have a professional grade scan tool that can access Mode $06 data, you can use the scan tool to look at the raw misfire data that is being tabulated for each cylinder. Normally the misfire counts should be zero or close to zero for every cylinder. The OBD II system will usually NOT set a misfire code until the actual misfire count exceeds about two percent for any given cylinder. So by looking at the actual Mode $06 misfire data, you should be able to see any cylinders that are showing an abnormally high misfire rate.</div>
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For example, if the Mode $06 scan tool data shows zero or close to zero misfires for all cylinders except cylinder number four (which has a count of say 80 or higher), that would tell you cylinder number four has an ignition, fuel or compression problem that will require further diagnosis.</div>
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FINDING THE CAUSE OF A STEADY OR CONTINUOUS MISFIRE</h3>
<span style="font-family: "arial";">In the case of a steady misfire, isolating the misfiring cylinder is the first step in diagnosing the problem. The old-fashioned method for finding a weak cylinder is to temporarily disconnect each of the spark plug wires, one at a time, while the engine is idling. When there's no change in the idle speed, then you have pinpointed the weak cylinder.</span><br />
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A power balance test will tell you the same thing, but this requires some hookups and an engine analyzer. A power balance test is preferable to pulling plug wires, because it keeps you away from the voltage and prevents the voltage from causing any damage to the electronics in the ignition system.</div>
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When a plug wire is physically disconnected from a spark plug, the high voltage surge from the coil cannot follow its normal path to ground through the plug wire and spark plug, so it passes back through the coil. Most ignition systems are robust enough to withstand such voltage backups intermittently but not on a prolonged basis. If the coil or ignition module is already weak, it may push the component over the brink causing it to fail.</div>
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ADVANCED MISFIRE DIAGNOSTICS WITH A DIGITAL STORAGE OSCILLOSCOPE</h3>
<span style="font-family: "arial";">A weak cylinder will stick out like a sore thumb on an ignition scope or a digital storage oscilloscope (DSO)</span><span style="font-family: "arial";">. The secondary parade pattern will reveal the firing voltages for each cylinder. The number one cylinder will be the first one on the display, followed by each of the other cylinders in their respective firing order, moving across the screen from left to right.</span><br />
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If the peak firing voltage for any cylinder is significantly higher or lower than the others, it indicates a problem. An usually low firing voltage would tell you the spark is finding a shortcut to ground. A fouled, shorted or cracked spark plug; arcing past the spark plug boot to ground; and a shorted plug wire would be the most likely causes. An unusually high firing voltage in a cylinder would tell you the spark plug electrode is too wide or too badly worn or that the plug wire is open.</div>
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If the firing voltages for all the cylinders are about equal with the engine idling, a snap-kV test will help you find a misfire that occurs when the engine is under load. To conduct this test, suddenly open the throttle wide and then let it fall back while observing the firing pattern on the scope. All the firing voltages should increase during the snap-kV acceleration test, but, if any individual cylinder increases significantly more or less than its companions, it indicates trouble.</div>
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A snap-kV voltage spike that is taller than the rest indicates high resistance in the ignition secondary to the affected cylinder. Check for excessive resistance or an open in the plug wire. A spike that is much shorter than the rest indicates loss of voltage. Check for a shorted, cracked or damaged spark plug, arcing across the spark plug boot or a shorted plug wire. Misfire under load accompanied by low overall spike heights during the snap-kV test would tell you the available voltage from the coil is low. The most likely cause, in this case, would be a faulty ignition coil. But low battery voltage might also be a factor, too. Be sure to check the battery and charging voltage.</div>
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The next thing you should look at is the primary pattern for the suspicious cylinder. The primary pattern can reveal additional pieces in the diagnostic puzzle. The primary pattern will show when the coil starts to charge, the peak or "arc-over" firing voltage (which you've already looked at and determined was higher or lower than normal), the "spark burn line" and coil oscillations.</div>
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The spark burn line is the part of the waveform that immediately follows the firing voltage spike. The height of this line can tell you if the air/fuel mixture is running rich or lean. If the fuel mixture is lean, then the spark burn line will be higher than normal. If the air/fuel mixture is rich, then the spark burn line will be lower than normal.</div>
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A lean mixture in a single cylinder can be caused by a leaky intake manifold gasket, air leakage past injector O-rings, a leaky EGR valve (if the valve is adjacent to the cylinder intake port) or a dirty, plugged or inoperative fuel injector. Loss of compression because of a leaky (burned) exhaust valve or a leaky head gasket can also affect the spark burn line in the same way.</div>
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Note: If the spark burn lines for all the cylinders are higher than normal (indicating a lean fuel mixture), the underlying cause would be something that affects all cylinders such as an intake manifold vacuum leak, leaky vacuum hose, leaky EGR valve, leaky throttle gasket or low fuel pressure (weak fuel pump or bad pressure regulator).</div>
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A rich fuel mixture in an individual cylinder is less common but can occur if the fuel injector leaks. A more common condition would be a rich condition in all cylinders caused by a dead oxygen sensor or coolant sensor that prevents the computer from going into closed loop, or by a faulty fuel pressure regulator that feeds too much pressure to the injectors.</div>
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Something else to look at in the spark burn line is the amount of "hash" it contains. A good cylinder will show a relatively clean line with little hash. A lot of hash, on the other hand, occurs when ignition misfire or lean misfire are present.</div>
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The duration or length of the spark burn line can provide more clues about what's going on inside the cylinder. If the duration of the burn line is longer than about 2 milliseconds, the air/fuel mixture is running abnormally rich for any of the reasons just given. If the burn line is shorter than about 0/75 milliseconds, then the cylinder is running too lean.</div>
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The last thing you want to look at in the primary ignition pattern is coil oscillations. If the coil is good, there should be at least two and preferably three or more oscillations after the burn line. Fewer oscillations would indicate a faulty coil.</div>
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IGNITION AND COMPRESSION MISFIRES</h3>
<span style="font-family: "arial";">If you have a misfire and have isolated it to one cylinder, the cause will be obvious when you remove the spark plug</span><span style="font-family: "arial";">. If the plug's insulator is cracked or broken, you've found the problem. If the plug appears to be OK but is wet, inspect the plug wire and boots for damage. Measure the plug wire's resistance, end to end, with an ohmmeter. Refer to the vehicle manufacturer's specifications, but, as a rule, resistance should not exceed 8,000 ohms per foot. Replace the wire if resistance exceeds specifications.</span><br />
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If the plug is fouled, you've found the source of the misfire, but you still have to determine what caused the plug to foul. Heavy black oily carbon deposits would tell you that the engine is burning oil. The most likely cause is worn valve guide seals and/or guides, but worn rings and cylinders can also allow oil to enter the combustion chamber. Replacing the spark plug will temporarily cure your customer's misfire problem, but, until the oil consumption problem is fixed, the engine will continue to foul plugs.</div>
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A leakdown test or compression test will help you determine if the oil is getting past the valve guides or the rings. If the cylinder shows little leakdown or holds good compression when a little oil is squirted into the cylinder (wet compression test), it would tell you that the engine needs new valve guide seals and/or guide work. Most late model engines have positive valve guide seals. Often, the guides are fine, but the seals are worn or cracked. The seals can be replaced on some engines without too much effort and without having to remove the head.</div>
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Just pull off the valve cover, remove the valvetrain hardware and use an external spring compressor to remove the springs so new seals can be installed. A regulated air hose connected to the spark plug hole will keep the valve from dropping into the cylinder. But, on many OHC engines, there's so much disassembly involved to get to the valve springs you may have to remove the head.</div>
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A spark plug that shows heavy whitish to brown deposits may indicate a coolant leak either past the head gasket or through a crack in the combustion chamber. This type of problem will only get worse and may soon lead to even greater problems if the leak isn't fixed. Coolant makes a lousy lubricant and can cause ring, cylinder and bearing damage if it gets into a cylinder or the crankcase.</div>
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Loss of coolant can also lead to overheating, which may result in cracking or warping of aluminum cylinder heads. If you suspect this kind of problem, pressure test the cooling system to check for internal coolant leakage.</div>
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Spark plugs that show preignition or detonation damage may indicate a need to check timing, the operation of the cooling system and conditions that cause a lean air/fuel mixture. You might also want to switch to a colder heat range plug.</div>
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Short trip stop-and-go driving can cause a rapid buildup of normal deposits on plugs, especially if the engine has a lot of miles and there has been some oil leakage past the valve guide seals and rings. The cure here might be to switch to a one-step hotter spark plug.</div>
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If the spark plug and plug wire are OK but the cylinder is weak, a leakdown or compression test should be done to determine if the problem is compression related. The exhaust valves are the ones most likely to lose their seal and leak compression, so, if you find unusually low compression, follow up with a wet compression test to determine if the problem lies with the valves or rings.</div>
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No change in compression with a wet test would tell you the problem is valve related (probably a bad exhaust valve) or a blown head gasket. But, if the compression readings are significantly higher with a wet compression test, it would tell you the piston rings and/or cylinder walls are worn.</div>
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Either way, your customer is looking at major repairs. The only cure for a leaky valve is a valve job, and the only cure for a leaky head gasket is to replace the gasket. Likewise, the only cure for worn rings and cylinders is to overhaul or replace the engine.</div>
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Low compression can also be caused by a rounded cam lobe. If the valve doesn't open, the cylinder can't breathe normally and compression will be low. A visual inspection of the valvetrain and cam will be necessary if you suspect this kind of problem.</div>
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<img alt="fuel injector and spark plug ignite fuel mixture" src="http://www.aa1car.com/library/fuel_injector_ignition.jpg" /><br /><i>A dirty fuel injector or fouled spark plug can cause misfires.</i></center>
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FUEL RELATED MISFIRES</h3>
<span style="font-family: "arial";">If the ignition components and compression in a misfiring cylinder are fine, that leaves a fuel related problem </span><span style="font-family: "arial";">as the only other possibility. You can start by checking for voltage at the injector. A good injector should also buzz while the engine is running. No buzzing would tell you the injector is dead, while a no-voltage reading would tell you it isn't the injector's fault but a wiring or computer driver problem.</span><br />
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If the injector is buzzing and spraying fuel but the cylinder isn't getting enough fuel, the injector is dirty or clogged. On-car cleaning may help remove the varnish deposits that are restricting the injector and restricting fuel delivery, but chances are, if the injector is clogged enough to cause a steady misfire, it will have to be removed for off-car cleaning or be replaced.</div>
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You can also observe injector performance on a scope, and check its response to changes in the air/fuel mixture. First of all, a flat line would tell you the injector is dead or is not receiving voltage (depending on where the line falls on the screen). If the injector is working, the line should drop when the injector turns on, then peak when the current is switched off.</div>
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The injector scope pattern will tell you how long the injector is on. If you make the air/fuel mixture artificially lean by momentarily pulling off a vacuum hose, and/or artificially rich by feeding some propane into the manifold, you should see a corresponding change in the injector on time as the computer responds to input from the oxygen sensor. No change would tell you either the O2 sensor is dead or there's a problem in the computer.</div>
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One thing that should always be checked if an injector is removed for cleaning and/or testing is its spray pattern. A good injector should produce a cone-shaped mist of fuel vapor. If you see solid streamers in the spray pattern or a solid stream of fuel, the injector needs attention. If off-car cleaning fails to restore the normal spray pattern, the injector must be replaced.</div>
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If you're dealing with a random misfire that can't be isolated to a particular cylinder, all the injectors may be dirty. You should also check fuel pressure to see if the pump is weak or the pressure regulator is defective. A plugged fuel filter can reduce fuel pressure. If fuel pressure is within specifications, check the intake vacuum to see if there is an air leak that's upsetting the overall air/fuel mixture. A couple of overlooked causes here may be a leaky EGR valve or a leaky power brake booster.</div>
Anonymoushttp://www.blogger.com/profile/07884952301771193295noreply@blogger.com0tag:blogger.com,1999:blog-2529084104041640172.post-67453987607599468562017-01-09T07:53:00.000-08:002017-01-09T08:09:17.060-08:00Engine & Driveability Problems: Engine Won't Start, No Fuel (Bad Fuel Pump?): 8 Diagnose Fuel Pump<center style="font-family: Arial;">
<img alt="diagnose fuel pump" src="http://www.aa1car.com/library/returntype_efi.gif" /><br /><h1>
Diagnose Fuel Pump</h1>
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If the fuel pump is not delivering adequate fuel pressure and volume to the engine, the engine may not start or run properly. Low fuel pressure can cause hard starting, a rough idle, misfiring, hesitation and stalling. No fuel pressure will prevent the engine from starting, or will cause the engine to quit running if the fuel pump fails while driving.</div>
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Fuel injected engines are very sensitive to fuel pressure as well as fuel volume. Low pressure will cause starting and driveability problems. A pump that can deliver adequate pressure but not enough volume may allow the engine to start and idle normally, but it will starve the engine for fuel and cause a loss of power when the engine is under load, accelerating hard or cruising at highway speeds.</div>
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Engine Cranks But Will Not Start</h3>
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A dead fuel pump can prevent an engine from starting, but so can a problem with the ignition system or the engine itself (such as a broken timing belt).</div>
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The first thing to check would be spark. This can be done by connecting a spark plug tester to a plug wire while the engine is cranking. The tester must be grounded to the engine block for a good electrical connection.</div>
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<b><i>CAUTION:</i></b><i> Do not touch any of the spark plug wires while the engine is being cranked or you may get a bad shock!</i></div>
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If an engine has a coil-on-plug ignition system, and it is possible to remove one of the coils, do so and place a spark plug in the end of the coil. Then place the coil and plug so the plug is touching metal on the engine.</div>
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If the ignition system is working properly, you should see a series of sparks while cranking the engine. No spark would indicate an ignition problem such as a bad crankshaft position sensor, ignition module or ignition coil.</div>
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Next, check the timing belt if the engine has an overhead camshaft and rubber timing belt. The belt is usually enclosed inside a plastic cover on the end of the engine. Removing a couple of screws from the cover and pulling the cover back should allow you to see the belt. If the belt looks okay, and turns when the engine is cranked, compression is probably not your problem. Timing belts can jump time if they loosen up or if the cogs on the underside of the belt become damaged. It's also possible for the overhead camshaft to seize or break if the engine has run low on oil or has overheated. But if the cam gear turns when the engine is cranked, that's probably not the problem either.</div>
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<b><i>CAUTION: </i></b><i>Keep your fingers away from the belt and gears while cranking the engine!</i></div>
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If ignition and compression are both OK, that leaves a lack of fuel as the most likely cause of the no start. But is it the fuel pump or something else?</div>
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Possible causes of a fuel-related no start include:</h3>
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1. A dead fuel pump (could be the pump, pump relay pump fuse or a fault in the pump wiring circuit)</div>
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2. A plugged fuel filter</div>
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3. Low fuel pressure (weak pump, restricted fuel line, low voltage to the pump or a defective fuel pressure regulator)</div>
<b style="font-family: Arial;">If the pump runs and generates normal pressure to the engine, but the engine still does not start, the problem may be:</b><br />
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1. No voltage to the fuel injectors (blown injector fuse or bad relay)</div>
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2. No pulse signal to the injectors from the PCM (no crank or cam sensor input to the PCM, or a bad driver circuit in the PCM, or a wiring harness problem)</div>
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3. A shorted fuel injector (robs voltage from the other injectors so none will operate)</div>
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Fuel Pump Checks</h3>
<span style="font-family: "arial";">One of the first things to check </span><span style="font-family: "arial";">is the fuel pump. Does the pump run when the engine is cranking? The pump should make a little noise. No noise would tell you the pump is not spinning.</span><br />
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On most vehicles the pump is energized by the PCM via a relay. When the ignition key is first turned on, the PCM energizes the fuel pump relay for a couple of seconds so the pump will run to build up pressure. The PCM then shuts off the fuel pump relay (which turns off the pump) if it does not receive an rpm signal from the engine indicating the engine has started after cranking. The pump circuit also may be wired though an oil pressure switch and/or an inertia safety switch that kills the pump in case of an accident. Refer to the wiring diagram to find out what is involved before jumping to any conclusions.</div>
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A bad fuel pump relay will prevent the fuel pump from running. Locate the fuel pump relay in the engine compartment (it is usually in the power center). Remove the relay and shake it. If you hear anything rattling inside the relay, the relay is broken and needs to be replaced.</div>
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To test the fuel pump, bypass the relay to route power directly to the fuel pump. If the fuel pump runs when the relay is bypassed, the problem is a bad relay or a fault in the wiring circuit that provides power to the relay. Bypassing a relay can be tricky because you have to know which terminals to jump. So before you attempt this procedure, you must look up the fuel pump wiring diagram for your vehicle in a manual or online.</div>
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One new tool we found recently (see below) makes bypassing a fuel pump relay much easier and requires no wiring diagrams or jumper wires. The tool is a fuel pump bypass relay. It is a replacement relay that has an ON-OFF rocker switch on top. All you do is replace your fuel pump relay with the test relay, flip the switch to energize the fuel pump and see if the fuel pump runs. If the pump works, the problem is a bad relay. If nothing happens, the problem is a bad fuel pump or a fault in the wiring between the relay and pump. The tool is made by IPAtools and comes in a kit that includes 6 different relays that fit a variety of import and domestic vehicles:</div>
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<a href="http://ipatools.com/products/index.php/ipa-9038.html?SID=276907e751c276b24e9f0583f9861853" style="font-family: Arial;" target="blank"><img alt="fuel pump relay bypass tool" src="http://www.aa1car.com/library/fuel_pump_relay_bypass_tool.jpg" /></a><br />
<i style="font-family: Arial;">Fuel pump relay bypass tool allows you to energize and test the fuel pump.</i><br />
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Other electrical problems that can affect the pump include low voltage in the pump's power supply circuit or high resistance in the pump's ground connection. Either may prevent the pump from running or spinning fast enough to generate normal fuel pressure.</div>
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Measuring Fuel Pump Pressure</h3>
<span style="font-family: "arial";">Depending on the application</span><span style="font-family: "arial";">, the fuel system may require anywhere from 30 to 80 psi of fuel pressure to start and run. </span><b style="font-family: Arial;">NOTE: </b><span style="font-family: "arial";">Fuel injected engines are VERY sensitive to fuel pressure. If pressure at the engine fuel rail is even a couple pounds less than specifications, the engine may not start or run well, or experience hesitation or stalling problems.</span><br />
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Pressure specifications will vary according to the type of fuel injection system on the engine as well as the performance, fuel economy and emission requirements of that particular model year vehicle. There are no rules of thumb. Every application is different, so always look up the pressure specs when troubleshooting fuel-related performance problems.</div>
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When there is too much fuel pressure, the engine runs rich. This causes an increase in fuel consumption and carbon monoxide (CO) emissions. An engine that is running really rich also may experience a rough idle, surging and possibly even carbon-fouled spark plugs.</div>
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When there is not enough fuel pressure, the engine may not start. Or if it does, it may idle roughly and run poorly. Low fuel pressure creates a lean fuel condition that can cause lean misfire, hesitation, rough idle, hesitation and misfire on acceleration.</div>
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To check fuel pressure, you need a gauge and a place to attach it. There are a number of different checks that can be made, including static or rest pressure (key on, engine off), residual fuel pressure, running pressure, maximum or "dead head" pressure and volume of fuel delivered. The fuel pressure regulator also should be tested, and a fuel pressure drop test performed to check for dirty fuel injectors.</div>
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Different vehicle manufacturers recommend different test procedures. On many European EFI systems, the OEMs recommend using a static pressure test with the engine and ignition off. This is done by bypassing the fuel pump relay and energizing the pump directly. Most domestic and Asian vehicle manufacturers, on the other hand, provide a test fitting on the fuel rail so pressure can be checked with the engine running.</div>
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If you are working on a vehicle that does not have a pressure test fitting, you will have to tee a pressure gauge into the fuel line just ahead of the injector fuel rail.</div>
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<i><b>Caution:</b> Before hooking up your pressure gauge, relieve all pressure in the fuel system.</i></div>
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<b>Static Fuel Pressure Test</b>With the key on, engine off (or with the fuel pump energized), fuel pressure should come up quickly and hold steady at a fixed value. Compare the pressure reading to specifications. If you get no pressure reading, check for voltage at the pump. If there is voltage but the pump is not running, you have found the problem: a bad fuel pump.</div>
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<b style="font-family: Arial;"></b><img alt="fuel injection test port" border="0" src="http://www.aa1car.com/library/elements/60324c.gif" height="187" style="font-family: Arial;" width="189" /><br />
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If you do get a pressure reading but the reading is lower than normal, the cause may be a weak pump, a blockage in the fuel line, filter or tank inlet sock, or a faulty pressure regulator. Also, low voltage at the pump may prevent it from spinning fast enough to build up normal pressure. Check the voltage at the pump. If OK, check the fuel filter and lines for obstructions and the operation of the fuel pressure regulator before you condemn the pump.</div>
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<b>Residual Fuel Pressure Test</b>When the pump is turned off or stops running, the system should hold residual pressure for several minutes (look up the specs to see how much pressure drop is allowed over a given period of time). If pressure drops quickly, the vehicle may have a leaky fuel line, a leaky fuel pump check valve, a leaky fuel pressure regulator or one or more leaky fuel injectors. Low residual fuel pressure can cause hard starting and vapor lock during hot weather.</div>
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<b>Running Fuel Pressure Test</b>With the engine idling, compare the gauge reading to specifications. Fuel pressure should be within the acceptable range given by the vehicle manufacturer. If low, the problem may be a weak pump, low voltage to the pump, a clogged fuel filter, line or inlet sock inside the fuel tank, a bad fuel pressure regulator, or nearly empty fuel tank.</div>
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<b>Dead Head Pressure</b>This checks the maximum output pressure of the fuel pump. With the return line pinched shut, the pump should produce two times its normal operating pressure at idle. If the pressure rating does not go up with the return line blocked, the pump may not be able to deliver enough fuel at higher engine speeds. Possible causes include a worn pump, low voltage at the pump, a plugged fuel filter or inlet sock in the tank, an obstructed fuel line or almost empty fuel tank.</div>
<b style="font-family: Arial;"></b><b style="font-family: Arial;"></b><b style="font-family: Arial;"></b><img alt="fuel pump volume test" src="http://www.aa1car.com/library/fuel_volume_test.gif" style="font-family: Arial;" /><br />
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Fuel Volume Test</h3>
<span style="font-family: "arial";">A fuel pump that delivers normal pressure may still cause driveability problems if it can't deliver enough fuel volume to meet the engine's needs. A fuel volume test may therefore be the best way to evaluate the pump's condition.</span><br />
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A fuel volume test measures the volume of fuel delivered over a specified interval. This test can be done by connecting a fuel flow gauge into the fuel supply line, or by disconnecting the fuel return line from the fuel pressure regulator and connecting a hose from the regulator to a large container. Caution: Make sure there are no open sparks or flames nearby while doing this test!</div>
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With the engine off, energize the pump and measure the volume of fuel delivered during the specified interval of time. As a rule, a good pump should deliver about 3/4 to one quart of fuel in 30 seconds.</div>
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Causes of low fuel volume delivered include a worn fuel pump, a plugged fuel filter or inlet sock in the tank, obstructed fuel line or nearly empty tank. Don't forget that low voltage at the pump can also prevent it from running fast enough to generate adequate fuel flow. The pump's supply voltage should be within half a volt of normal system voltage. If it is low, check the wiring connectors, relay and ground.</div>
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Fuel Pressure Regulator Tests</h3>
<span style="font-family: "arial";">This test checks the operation of the fuel pressure regulator to make sure it changes line pressure in response to changes in engine vacuum. This is necessary to maintain the proper operating pressure behind the injectors and to compensate for changes in engine load.</span><br />
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With the engine running, disconnect the vacuum hose from the pressure regulator. As a rule, fuel system pressure should increase 8 to 10 psi with the line disconnected. No change would indicate a faulty pressure regulator, or a leaky or plugged vacuum line.</div>
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Also, when the vacuum hose is disconnected from the regulator, check the inside of the hose for any wetness that would indicate fuel is being sucked into the hose. There should be none. If the inside of the hose is wet, it means the diaphragm inside the regulator is leaking. This will cause a drop in fuel pressure, and allow fuel to be sucked into the intake manifold upsetting the air/fuel mixture. If the diaphragm is leaking, replace the regulator.</div>
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Fuel Pressure Drop Test</h3>
<span style="font-family: "arial";">This test measures the drop in static system fuel pressure when each injector is energized. The amount of pressure drop for each injector is then compared to see if the injectors are dirty and need to be cleaned or replaced. This test requires an "injector pulser" tool to energize the injectors.</span><br />
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To perform this test, turn the key on or energize the fuel pump for a few seconds to build up static pressure in the fuel system. Then turn the key off, pulse one injector for the specified time and note the pressure drop for that injector. Turn the key back on to rebuild static pressure and repeat the test for each of the remaining injectors.</div>
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An injector that is pulsed 100 times for five milliseconds should produce a minimum pressure drop of about 1 to 3 psi, and no more than 5 to 7 psi, depending on the application.</div>
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The difference in pressure drop between all the injectors should be 2 psi or less. If you see more than 3 psi difference between the highest and lowest readings, the injectors are dirty and need to be cleaned or replaced.</div>
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If you see no pressure drop when an injector is energized, the injector is clogged or defective and needs to be replaced. If the pressure gauge needle bounces, the injector is sticking.</div>
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After cleaning, repeat the test to see if cleaning did the trick. All injectors should show about the same amount of pressure drop (less than 2 psi difference) and no more than 7 psi drop at 100 pulses for 5 milliseconds. If there is no change in the readings or the drop exceeds these limits, the injector(s) need to be replaced.</div>
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Fuel System Scan Tool Checks</h3>
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If you have a scan tool that can display OBD system data, look for a fuel pressure PID. Compare the fuel pressure reading against specifications to see if it is in range or not. You can also compare the scan tool pressure reading against the actual reading on the vehicle with a gauge to see if they are the same. If the gauge reads higher, the vehicle may have a bad fuel pressure sensor. A low fuel pressure reading would confirm a weak fuel pump, low voltage to the fuel pump or a leaky fuel pressure regulator that does not allow the system to develop and hold normal fuel pressure.</div>
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You can also look at Long Term Fuel Trim (LTDT) and Short Trim Fuel Trim (STFT) values to see if the engine is running lean. A normal range is usually plus or minus 8 or less. A STFT value greater than 8 or a LTFT value greater than 10 would tell you the engine is running lean, possibly due to low fuel pressure or a weak fuel pump. Just remember that lean readings can also be caused by engine vacuum leaks and other conditions.</div>
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Fuel pumps can also be tested with a professional level scan tool that has bidirectional capabilities. On the scan tool diagnostics menu, there may be an option to run a fuel pump self-test. The test allows you to energize the pump to see if it runs, and to test the operation of a variable speed pulse-modulated pump.</div>
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You can also use any scan tool or code reader to pull fuel-related fault codes from the PCM.</div>
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Fuel System Scope Tests</h3>
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By connecting a Low Amps probe to the fuel pump's voltage supply wire, you can view the pump's current waveform on a digital storage oscilloscope (DSO). The scope pattern will reveal internal wear in the brushes and commutator that may not show up in a traditional pressure or volume test.</div>
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Observing the waveform will show if the pump's amp draw is normal for the application or is high or low, and if the pump is operating at normal speed or is running slow. Problems such as a bad spot on a commutator or a short or open in the armature also will be obvious in the waveform.</div>
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A "good" electric fuel pump waveform will generally seesaw back and forth with relative consistency and minimal variation between the highs and lows. A "bad" waveform will show large or irregular drops in the pattern, with large differences between the highs and lows.</div>
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Fuel Pump Replacement</h3>
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What To Do if the Fuel Pump Checks Out Okay, but the Engine Still Won't Start</h3>
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If the fuel pump is running and delivering normal pressure to the engine, and the engine has spark and compression, but will not start, the fuel injectors are probably not opening. The PCM uses the trigger signal from the crankshaft position sensor, and/or camshaft position sensor to pulse the injectors. The injectors should receive battery voltage when the key is turned on, and the PCM driver circuit provides the ground connection to energize the injectors.</div>
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The first check would be to check for voltage at the injectors when the key is turned on. No voltage? The problem could be a blown injector circuit fuse, a bad fuel injector power relay, or a fault in the wiring harness to the injectors. The injector fuse and relay are usually located in the relay box or power distribution center in the engine compartment.</div>
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If the fuse is okay, try swapping the relay with another to see if that gets voltage to the injectors so the engine will start. No change? Then the PCM may not be pulsing the injectors, or there may be a shorted injector that is robbing power from the circuit preventing the other injectors from opening.</div>
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<b>TIP:</b> Try unplugging the injectors one at a time and cranking the engine to see if it will start. If the engine starts when a particular injector has been unplugged, that's the shorted injector that needs to be replaced.</div>
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<b>TIP:</b> You can also measure the resistance of each injector with an ohmmeter. Unplug the injector and measure the resistance between the two terminals. If resistance is outside specifications (high or low), replace the injector.</div>
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Professional technicians use a tool called a NOID light to check injector pulses. The tool detects digital signals in a circuit and flashes an LED light. No flashes from the injector circuit when cranking the engine would tell you the PCM is not pulsing the injectors. On newer gasoline direct injection (GDI) systems, however, a NOID light is no help.</div>
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If the injectors appear to be working, but the engine is still not starting, the engine may be flooded with TOO MUCH fuel (remove a spark plug to see if it is wet). Let the engine sit awhile, then try again, or hold the gas pedal all the way down when cranking to put the PCM into the "Clear Flood" mode when starting the engine.</div>
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<b>NOTE:</b> Hard starting problems are sometimes the result of an improper starting technique on the part of the driver. On a fuel injected engine, DO NOT push or pump the gas pedal when trying to start the engine. This just puts the engine into the Clear Flood mode, which will cut off fuel to the engine temporarily making it even harder to start. Just crank the engine without touching the gas pedal.</div>
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Anonymoushttp://www.blogger.com/profile/07884952301771193295noreply@blogger.com0tag:blogger.com,1999:blog-2529084104041640172.post-48249631693141802502017-01-09T07:37:00.000-08:002017-01-09T07:37:20.303-08:00 Engine & Driveability Problems: 7 Engine Won't Crank or Start<center style="font-family: Arial;">
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Engine Won't Crank or Start</h1>
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What To Do When Your Car Won't Start</h3>
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Every engine requires four basic ingredients to start: sufficient cranking speed, good compression, adequate ignition voltage (with correct timing) and fuel (a relatively rich air/fuel mixture initially). So if your car fails to start, you can assume it lacks one of these four essential ingredients. But which one?</div>
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To find you, you need to analyze the situation. If the engine won't crank, you are probably dealing with a starter or battery problem. Has the starter been acting up? (unusual noises, slow cranking, etc.). Is this the first time the engine has failed to crank or start, or has it happened before? Have the starter, battery or battery cables been replaced recently? Might be a defective part. Has the battery been running down? Might be a charging problem. Have there been any other electrical problems? The answers to these questions should shed some light on what might be causing the problem.</div>
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If an engine cranks but refuses to start, it lacks ignition, fuel or compression. Was it running fine but quit suddenly? The most likely causes here would be a failed fuel pump, ignition module or broken overhead cam timing belt. Has the engine been getting progressively harder to start? If yes, consider the engine's maintenance and repair history.</div>
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NO START DIAGNOSIS</h3>
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What happens when you attempt to start the engine? If nothing happens when you turn the key, check the battery<b><a href="http://www.aa1car.com/library/2003/us20310.htm"> </a></b>to determine its state of charge. Many starters won't do a thing unless there is at least 10 volts available from the battery. A low battery does not necessarily mean the battery is the problem, though. The battery may have been run down by prolonged cranking while trying to start the engine. Or, the battery's low state of charge may be the result of a charging system problem. Either way, the battery needs to be recharged and tested.</div>
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If the battery is low, the next logical step might be to try starting the engine with another battery or a charger. If the engine cranks normally and roars to life, you can assume the problem was a dead battery, or a charging problem that allowed the battery to run down. If the battery accepts a charge and tests okay, checking the output of the charging system should help you identify any problems there.</div>
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A charging system that is working properly should produce a charging voltage of somewhere around 14 volts at idle with the lights and accessories off. When the engine is first started, the charging voltage should rise quickly to about two volts above base battery voltage, then taper off, leveling out at the specified voltage. The exact charging voltage will vary according to the battery's state of charge, the load on the electrical system, and temperature. The lower the temperature, the higher the charging voltage. The higher the temperature, the lower the charging voltage. The charging range for a typical alternator might be 13.9 to 14.4 volts at 80 degrees F, but increase to 14.9 to 15.8 volts at subzero temperatures.</div>
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If the charging system is not putting out the required voltage, is it the alternator or the regulator? Full fielding the alternator to bypass the regulator should tell you if it is working correctly. Or, take the alternator to a parts store and have it bench tested. If the charging voltage goes up when the regulator is bypassed, the problem is the regulator (or the engine computer in the case of computer-regulated systems). If there is no change in output voltage, the alternator is the culprit.</div>
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Many times one or more diodes in the alternator rectifier assembly will have failed, causing a drop in the unit's output. The alternator will still produce current, but not enough to keep the battery fully charged. This type of failure will show up on an oscilloscope as one or more missing humps in the alternator waveform. Most charging system analyzers can detect this type of problem.</div>
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ENGINE CRANKING PROBLEMS</h3>
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If your car won't start because the engine won't crank or cranks slowly (and the battery is fully charged), you can focus your attention on the starter circuit. A quick way to diagnose cranking problems is to switch on the headlights and watch what happens when you attempt to start the engine. If the headlights go out, a poor battery cable connection may be strangling the flow of amps. All battery cable connections should be checked and cleaned along with the engine-to-chassis ground straps.</div>
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Measuring the voltage drop<b> </b>across connections is a good way to find excessive resistance. A voltmeter check of the cable connections should show no more than 0.1 volt drop at any point, and no more than 0.4 volts for the entire starter circuit. A higher voltage drop would indicate excessive resistance and a need for cleaning or tightening.</div>
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Slow cranking can also be caused by undersized battery cables. Some cheap replacement cables have small gauge wire encased in thick insulation. The cables look the same size as the originals on the outside, but inside there is not enough wire to handle the amps.</div>
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If the headlights continue to shine brightly when you attempt to start the engine and nothing happens (no cranking), voltage is not reaching the starter. The problem here is likely an open or misadjusted park/neutral safety switch, a bad ignition switch, or a faulty starter relay or solenoid. Fuses and fusible links should also be checked because overloads caused by continuous cranking or jump starting may have blown one of these protective devices.</div>
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If the starter or solenoid clicks but nothing else happens when you attempt to start the engine, there may not be enough amps to spin the starter. Or the starter may be bad. A poor battery cable, solenoid or ground connection, or high resistance in the solenoid itself may be the problem. A voltage check at the solenoid will reveal if battery voltage is passing through the ignition switch circuit. If the solenoid or relay is receiving battery voltage but is not closing or passing enough amps from the battery to spin the starter motor, the solenoid ground may be bad or the contacts in the solenoid may be worn, pitted or corroded. If the starter cranks when the solenoid is bypassed, a new solenoid is needed, not a starter.</div>
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Most engines need a cranking speed of 200 to 300 rpm for your car to start, so if the starter is weak and can't crank the engine fast enough to build compression, the engine won't start. In some instances, a weak starter may crank the engine fast enough but prevent it from starting because it draws all the power from the battery and does not leave enough for the injectors or ignition system.</div>
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If the lights dim and there is little or no cranking when you attempt to start the engine, the starter may be locked up, dragging or suffering from high internal resistance, worn brushes, shorts or opens in the windings or armature. A starter current draw test will tell you if the starter is pulling too many amps.</div>
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A good starter will normally draw 60 to 150 amps with no load on it, and up to 200 amps or more while cranking the engine. The no-load amp draw depends on the rating of the starter while the cranking amp draw depends on the displacement and compression of the engine. Always refer to the OEM specs for the exact amp values. Some "high torque" GM starters, for example, may have a no load draw of up to 250 amps. Toyota starters on four-cylinder engines typically draw 130 to 150 amps, and up to 175 amps on six-cylinder engines.</div>
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An unusually high current draw and low free turning speed or cranking speed typically indicates a shorted armature, grounded armature or field coils, or excessive friction within the starter itself (dirty, worn or binding bearings or bushings, a bent armature shaft or contact between the armature and field coils). The magnets in permanent magnet starters can sometimes break or separate from the housing and drag against the armature.</div>
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A starter that does not turn at all and draws a high current may have a ground in the terminal or field coils, or a frozen armature. On the other hand, the start may be fine but can't crank the engine because the engine is seized or hydrolocked. So before you condemn the starter, try turning the engine over by hand. Won't budge? Then the engine is probably locked up.</div>
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A starter that won't spin at all and draws zero amps has an open field circuit, open armature coils, defective brushes or a defective solenoid. Low free turning speed combined with a low current draw indicates high internal resistance (bad connections, bad brushes, open field coils or armature windings).</div>
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If the starter motor spins but fails to engage the flywheel, the cause may be a weak solenoid, defective starter drive or broken teeth on the flywheel. A starter drive that is on the verge of failure may engage briefly but then slip. Pull the starter and inspect the drive. It should turn freely in one direction but not in the other. A bad drive will turn freely in both directions or not at all.</div>
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ENGINE CRANKS BUT YOUR CAR WILL NOT START</h3>
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When the engine cranks normally but you car won't start, you need to check ignition, fuel and compression. Ignition is easy enough to check with a spark tester or by positioning a plug wire near a good ground. No spark? The most likely causes would be a failed ignition module, distributor pickup or cranksahaft position (CKP) sensor.</div>
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A tool such as an Ignition System Simulator can speed the diagnosis by quickly telling you if the ignition module and coil are capable of producing a spark with a simulated timing input signal. If the simulated signal generates a spark, the problem is a bad distributor pickup or crankshaft position sensor. No spark would point to a bad module or coil. Measuring ignition coil primary and secondary resistance can rule out that component as the culprit.</div>
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Module problems as well as pickup problems are often caused by loose, broken or corroded wiring terminals and connectors. Older GM HEI ignition modules are notorious for this. If you are working on a distributor less ignition system with a Hall effect crankshaft position sensor, check the sensor's reference voltage (VRef) and ground. The sensor must have 5 volts or it will remain permanently off and not generate a crank signal (which should set a fault code). Measure VRef between the sensor power supply wire and ground (use the engine block for a ground, not the sensor ground circuit wire). Don't see 5 volts? Then check the sensor wiring harness for loose or corroded connectors. A poor ground connection will have the same effect on the sensor operation as a bad VRef supply. Measure the voltage drop between the sensor ground wire and the engine block. More than a 0.1 voltage drop indicates a bad ground connection. Check the sensor mounting and wiring harness.</div>
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If a Hall effect crank sensor has power and ground, the next thing to check would be its output. With nothing in the sensor window, the sensor should be "on" and read 5 volts (VRef). Measure the sensor D.C. output voltage between the sensor signal output wire and ground (use the engine block again, not the ground wire). When the engine is cranked, the sensor output should drop to zero every time the shutter blade, notch, magnetic button or gear tooth passes through the sensor. No change in voltage would indicate a bad sensor that needs to be replaced.</div>
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If the primary side of the ignition system seems to be producing a trigger signal for the coil but the voltage is not reaching the plugs, a visual inspection of the coil tower, distributor cap, rotor and plug wires should be made to identify any defects that might be preventing the spark from reaching its intended destination.</div>
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ENGINE CRANKS, HAS SPARK BUT WILL NOT START</h3>
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If you see a good hot spark when you crank the engine, but it won't start, check for fuel. The problem might be a bad fuel pump.</div>
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On an older engine with a carburetor, pump the throttle linkage and look for fuel squirting into the carburetor throat. No fuel? Possible causes include a bad mechanical fuel pump, stuck needle valve in the carburetor, a plugged fuel line or fuel filter.</div>
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On newer vehicles with electronic fuel injection, connect a pressure gauge to the fuel rail to see if there is any pressure in the line. No pressure when the key is on? Check for a failed fuel pump, pump relay, fuse or wiring problem. On Fords, don't forget to check the inertia safety switch which is usually hidden in the trunk or under a rear kick panel. The switch shuts off the fuel pump in an accident. So if the switch has been tripped, resetting it should restore the flow of fuel to the engine. Lack of fuel can also be caused by obstructions in the fuel line or pickup sock inside the tank. And don't forget to check the fuel gauge. It is amazing how many no starts are caused by an empty fuel tank.</div>
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There is also the possibility that the fuel in the tank may be heavily contaminated with water or overloaded with alcohol. If the tank was just filled, bad gas<b><a href="http://www.aa1car.com/library/us10325.htm"> </a></b>might be causing the problem.</div>
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On EFI-equipped engines, fuel pressure in the line does not necessarily mean the fuel is being injected into the engine. Listen for clicking or buzzing that would indicate the injectors are working. No noise? Check for voltage and ground at the injectors. A defective ECM may not be driving the injectors, or the EFI power supply relay may have called it quits. Some EFI-systems rely on input from the camshaft position sensor to generate the injector pulses. Loss of this signal could prevent the system from functioning.</div>
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Even if there is fuel and it is being delivered to the engine, a massive vacuum leak<b> </b>could be preventing the engine from starting. A large enough vacuum leak will lean out the air/fuel ratio to such an extent that the mixture won't ignite. An EGR valve that is stuck wide open, a disconnected PCV hose, loose vacuum hose for the power brake booster, or similar leak could be the culprit. Check all vacuum connections and listen for unusual sucking noises while cranking.</div>
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ENGINE HAS FUEL AND SPARK BUT WILL NOT START</h3>
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An engine that has fuel and spark, no serious vacuum leaks and cranks normally should start. The problem is compression. If it is an overhead cam engine with a rubber timing belt, a broken timing belt would be the most likely cause especially if the engine has a lot of miles on it. Most OEMs recommend replacing the OHC timing belt every 60,000 miles for preventative maintenance, but many belts are never changed. Eventually they break, and when they do the engine stops dead in its tracks. And in engines that lack sufficient valve-to-piston clearance as many import engines and some domestic engines do, it also causes extensive damage (bent valves and valvetrain components & sometimes cracked pistons).</div>
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Overhead cams can also bind and break if the head warps due to severe overheating, or the cam bearings are starved for lubrication. A cam seizure may occur during a subzero cold start if the oil in the crankcase is too thick and is slow to reach the cam (a good reason for using 5W-20 or 5W-30 for winter driving). High rpm cam failure can occur if the oil level is low or the oil is long overdue for a change.</div>
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With high mileage pushrod engines, the timing chain may have broken or slipped. Either type of problem can be diagnosed by doing a compression check and/or removing a valve cover and watching for valve movement when the engine is cranked.</div>
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A blown head gasket may prevent an engine from starting if the engine is a four cylinder with two dead cylinders. But most six or eight cylinder engines will sputter to life and run roughly even with a blown gasket. The gasket can, however, allow coolant to leak into the cylinder and hydrolock the engine.</div>
Anonymoushttp://www.blogger.com/profile/07884952301771193295noreply@blogger.com0tag:blogger.com,1999:blog-2529084104041640172.post-58567399172044489572017-01-09T07:19:00.003-08:002017-01-09T07:37:37.980-08:00 Engine & Driveability Problems: 6 Car Won't Start?<center style="font-family: Arial;">
<img alt="car starting problem" src="http://www.aa1car.com/library/elements/car_start_problem.jpg" /><br /><h1>
Car Won't Start?</h1>
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YOU TRY TO START YOUR CAR BUT IT WON'T START<br />
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What should you do when your car won't start? Diagnosing a no-start condition requires a logical approach to figuring out what might be preventing your car from starting. Below is a list of possible causes that can prevent your car from starting.</div>
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When you turn the ignition key to start your car, or press the START button, voltage from the battery flows through the ignition switch to the Park/Neutral safety switch and/or brake pedal or clutch pedal safety switch (you have to push the pedal down before the circuit will complete) to the starter relay or solenoid. When the relay or solenoid is energized by voltage from the ignition switch circuit, it closes a contact that routes more power from the battery directly to the starter to crank the engine. The starter motor spins, pushes the starter drive gear to engage the flywheel and cranks the engine.</div>
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If the engine fails to crank, there is a fault in one of the components in the battery/ignition/starter circuit.</div>
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COMMON CAUSES OF NO-CRANK NO-START</h3>
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<b>Low battery</b> (Check battery voltage, recharge if low, or jump start with another vehicle or battery charger).<br />
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<b>Loose or corroded battery cables</b> (Inspect, clean and tighten BOTH ends of BOTH battery cables).<br />
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<b>Bad starter relay wiring connections or ground connection</b> (Inspect, clean, tighten wiring connections).<br />
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<b>Bad starter relay/solenoid</b> (Check for voltage at the relay, if relay has voltage but there is no "click" when key is turned to start, replace relay).<br />
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<b>Bad starter</b> (Jump battery voltage direct to starter to see if it spins, or remove starter and have it bench tested at auto parts store).<br />
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<b>Damaged starter drive or teeth on flywheel</b> (Remove starter and inspect drive gear and flywheel teeth, replace damaged parts if necessary).<br />
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<b>Bad ignition switch</b> (Check to see if voltage reaches starter relay/solenoid when turn to start. If not, check for open P/N switch and brake or clutch pedal switch. Replace ignition if defective).<br />
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<b>Open P/N safety switch, or open Brake Pedal Safety Switch</b> (automatic transmission) or open Clutch Pedal Switch (manual transmission). Bypass switch with jumper wire to see if engine cranks, or use test light or voltmeter to check for voltage passing through switch when ignition is turned to start.<br />
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<b>Dead Smart Key Fob battery</b> Refer to owners manual for emergency starting procedure if your Key fob won't start your car. On some vehicles, placing the fob next to the push start button, pressing the Start button with the fob, or inserting the fob into a special slot on the instrument panel, steering column or center console may allow it to communicate with the ignition system so your engine will crank and start.<br />
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<b>Engine seized due to bearing failure or internal damage</b> (Use a socket and long handle to see if the engine can be turned by hand, if not the engine is locked up).<br />
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<b>Engine hydrolocked</b> due to coolant leak from leaky head gasket (Use socket and wrench to see if engine rotates, remove spark plugs and see if coolant comes out or engine can not be cranked with plugs out).</div>
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ENGINE CRANKS OKAY BUT WON'T START</h3>
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If the engine cranks over normally when you attempt to start your car, but the engine does not start, the problem may be <b>NO FUEL, NO SPARK or NO COMPRESSION</b>. The engine needs adequate fuel pressure, a properly timed spark and normal compression to start.</div>
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<b>TIP:</b> To find why the engine won't start, remove the air inlet tube from the throttle body, push the throttle open and spray a small amount of aerosol starting fluid into the engine. Crank the engine. IF it has spark and compression but NO FUEL, it will start and run a few seconds before dying. If it does NOT start, it probably has NO SPARK.<br />
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<b>TIP:</b> Another method to check for spark is to pull a spark plug wire off of a spark plug (if it has plug wires, coil-on-plug ignitions do not) and place the open end of the plug wire near a metal surface on the engine. Have a helper crank the engine while you watch for a spark. DO NOT hold the wire while doing this as it can shock you. If you see a spark, the problem is not spark, but most likely NO FUEL or NO COMPRESSION. If you do not see a spark, the problem is in the IGNITION CIRCUIT.<br />
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<b>TIP:</b> Proper fuel pressure is critical for fuel injected engines to start and run. You should hear the fuel pump inside the fuel tank buzz for a couple of seconds when the ignition is turned on (no buzz means the pump is not running and the engine is not getting fuel). You can smell the tailpipe for gasoline vapors after cranking the engine. If you smell gas, the problem is likely not fuel but NO SPARK. You can also remove the plastic cap and press the schraeder valve test fitting on the fuel rail to see if there is any fuel pressure to the engine (not a very accurate test because fuel pressure must be at a certain level for the engine to start, for that you need a gauge). Even so, no fuel at the fuel rail would tell you fuel is not getting to the engine.</div>
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<img alt="typical fuel pump power circuit" src="http://www.aa1car.com/library/fuelpump_circuit_typical.jpg" /></center>
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FUEL RELATED CAUSES OF "NO START"</h3>
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<b>Anti-Theft system issue</b>. If your Anti-Theft light is flashing, the anti-theft system is disabling the fuel pump to prevent the engine from starting. The problem could be a defective chip in a smart key, or a dead battery in a smart key or keyless entry fob, or a fault in the Anti-Theft system itself.</div>
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<b>Bad fuel pump</b> (Pump should run for a few seconds when ignition key is turned to start, no buzz means no fuel delivery to the engine).<br />
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<b>Bad fuel pump relay</b> (Relay is energized by PCM to route power to fuel pump when ignition is on).<br />
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<b>Bad inertia fuel shut-off safety switch</b> (Shuts off fuel in an accident, may have been tripped by a severe jolt, press button to reset).<br />
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<b>Open in wiring</b> anywhere in fuel pump wiring circuit (power or ground). Problem may be at wiring connector on top of fuel tank (hard to reach!).<br />
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<b>No gas in fuel tank</b> (Check the fuel gauge, and keep in mind the gauge may not be reading accurately).<br />
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<b>Bad gas</b> (Contaminated with water or too much alcohol or diesel fuel). If you just filled up with gas and now your car won't start, suspect bad gas.<br />
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<b>Plugged Fuel Filter</b> (When was the filter last changed?). Replace the filter. If plugged with rust,k fuel tank may also need to be cleaned or replaced.<br />
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<b>Plugged or Pinched Fuel Line</b> (Inspect fuel lines under vehicle for damage).<br />
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<b>Leaky Fuel Pressure Regulator</b> (Controls fuel pressure to injectors, which is critical for starting and proper air/fuel mixture).<br />
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<b>No power to Fuel Injectors</b> (Due to faulty fuel injector relay, blown fuse, no input signal to PCM from crank position sensor or cam position sensor, or bad PCM driver circuit). Injectors should usually have power when key is on. PCM grounds other side of injector circuit to pulse the injectors.<br />
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<b>Major vacuum leak </b>(An open EGR valve, disconnected vacuum hose, PCV valve, etc, can create a large vacuum leak and allow too much air to be sucked into the engine. This will make the air/fuel mixture too lean and make the engine hard to start. Engine will usually idle rough if it does start.</div>
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<img alt="typical ignition circuit" src="http://www.aa1car.com/library/ignition_circuit_typical.jpg" /></center>
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IGNITION RELATED CAUSES OF "NO START"</h3>
<b style="font-family: Arial;">Bad crankshaft position sensor</b><span style="font-family: "arial";"> or distributor pickup (Sends pulse signal to ignition module and/or PCM that is necessary to trigger the ignition coil(s)).</span><br />
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<b style="font-family: Arial;">Bad ignition module</b><span style="font-family: "arial";"> (controls firing of ignition coil(s), may have an intermittent open in circuitry that causes loss of spark, hard starting or sudden stalling, usually when hot)</span><br />
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<b style="font-family: Arial;">Bad ignition coil(s).</b><span style="font-family: "arial";"> Ignition coil creates high voltage to fire the spark plugs. On engines with a distributor, a bad coil will prevent spark at all the spark plugs. On engines with a distributor less ignition system or coil-on-plug ignition, a bad coil will only affect one or two cylinders depending on the appliacation</span><span style="font-family: "arial";">. This may make the engine hard to start, but it will run on the remaining cylinders that are firing.</span><br />
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<b style="font-family: Arial;">Cracks or carbon tracks inside distributor cap or on rotor</b><span style="font-family: "arial";"> (on older engines with distributors, cracks or carbon tracks allow spark to short to ground before it reaches the spark plugs). Same thing can happen in coil-on-plug ignition systems if cracks or carbon tracks inside coil tube.</span><br />
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<b style="font-family: Arial;">Bad spark plug wires </b><span style="font-family: "arial";">(if wet, cracked, burned or internal resistance exceeds specifications, can interfere with good spark and make engine hard to start).</span><br />
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<b style="font-family: Arial;">Fouled spark plugs </b><span style="font-family: "arial";">(if the electrodes are contaminated with deposits, spark may short to ground before jumping gap causing misfires. Can make engine hard to start and run poorly. If plugs are wet when removed, it means they are not firing or engine is flooded).</span><br />
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COMMON CAUSES OF NO COMPRESSION</h3>
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<b>Broken timing belt or chain</b> (Belt failure will prevent the valves from opening. The engine will NOT run if the belt has broken, and it may have bent valves or other damage as a result of the belt breaking).<br />
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<b>Broken camshaft</b> (This can happen on an overhead cam engine if the engine has overheated, warped the head and seized the camshaft).<br />
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<b>Plugged catalytic converter</b> (Creates a restriction that causes exhaust backpressure to back up. Engine may start but usually dies within a minute or two)</div>
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Anonymoushttp://www.blogger.com/profile/07884952301771193295noreply@blogger.com1tag:blogger.com,1999:blog-2529084104041640172.post-11944633017362380642017-01-09T07:03:00.003-08:002017-01-09T07:03:38.371-08:00Engine & Driveability Problems: 5 How To Find & Fix Coolant Leaks<center style="font-family: Arial;">
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How To Find & Fix Coolant Leaks</h1>
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Coolant leaks can occur anywhere in the cooling system. Nine out of ten times, coolant leaks are easy to find because the coolant can be seen dripping, spraying, seeping or bubbling from the leaky component. The first symptom of trouble is usually engine overheating. But your car may also have a Low Coolant indicator lamp. If you suspect your vehicle has a coolant leak, open the hood and visually inspect the engine and cooling system for any sign of liquid leaking from the engine, radiator or hoses. The color of the coolant may be green, orange or yellow depending on the type of antifreeze in the system. You may also notice a sweet smell, which is a characteristic odor of ethylene glycol antifreeze.</div>
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<img alt="cooling system leaks" src="http://www.aa1car.com/library/elements/cooling_system.gif" /><br /></center>
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The most common places where coolant may be leaking are:</h2>
<img alt="a bad water pump shaft seal can leak coolant" src="http://www.aa1car.com/library/elements/water_pump_shaft_seal.jpg" style="font-family: Arial;" /><span style="font-family: Arial;"> </span><i style="font-family: Arial;">A worn seal on the water pump shaft can leak coolant.</i><br style="font-family: Arial;" /><b style="font-family: Arial;"></b><br />
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<b>Water pump</b> -- A bad shaft seal will allow coolant to dribble out of the vent hole just under the water pump pulley shaft. If the water pump is a two-piece unit with a backing plate, the gasket between the housing and back cover may be leaking. The gasket or o-ring that seals the pump to the engine front cover on cover-mounted water pumps can also leak coolant. Look for stains, discoloration or liquid coolant on the outside of the water pump or engine.</div>
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<img alt="radiator corrosion" src="http://www.aa1car.com/library/elements/radiator_corrosion.jpg" style="font-family: Arial;" /><span style="font-family: Arial;"> </span><i style="font-family: Arial;">This radiator is badly corroded and is not worth fixing</i><span style="font-family: Arial;"> </span><br style="font-family: Arial;" /><b style="font-family: Arial;"></b><br />
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<b>Radiator</b> -- Radiators can develop leaks around upper or loser hose connections as a result of vibration. The seams where the core is mated to the end tanks is another place where leaks frequently develop, especially on aluminum radiators with plastic end tanks. On copper/brass radiators, leaks typically occur where the cooling tubes in the core are connected or soldered to the core headers. The core itself is also vulnerable to stone damage. Internal corrosion caused by old coolant that has never been changed can also eat through the metal in the radiator, causing it to leak.</div>
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Most cooling systems today are designed to operate at 8 to 14 psi. If the radiator can't hold pressure, your engine will overheat and lose coolant.</div>
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<img alt="radiator hose can leak coolant" src="http://www.aa1car.com/library/elements/hose_check.jpg" style="font-family: Arial;" /><span style="font-family: Arial;"> </span><i style="font-family: Arial;">Pinch hoses to check for age cracks, hardening, soft spots, blisters or bulges.</i><br style="font-family: Arial;" /><b style="font-family: Arial;"></b><br />
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<b>Hoses</b> -- Cracks, pinholes or splits in a radiator hose or heater hose will leak coolant. A hose leak will usually send a stream of hot coolant spraying out of the hose. A corroded hose connection or a loose or damaged hose clamp may also allow coolant to leak from the end of a hose. Sometimes the leak may only occur once the hose gets hot and the pinhole or crack opens up.</div>
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<b>Freeze plugs</b> -- These are the casting plugs or expansion plugs in the sides of the engine block and/or cylinder head. The flat steel plugs corroded from the inside out, and may develop leaks that are hard to see because of the plug's location behind the exhaust manifold, engine mount or other engine accessories. On V6 and V8 blocks, the plugs are most easily inspected from underneath the vehicle.</div>
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<b>Heater Core</b> -- The heater core is located inside the heating ventilation and air conditioning (HVAC) unit under the dash. It is out of sight so you cannot see a leak directly. But if the heater core is leaking (or a hose connection to the heater core is leaking), coolant will be seeping out of the bottom of the HVAC unit and dripping on the floor inside the passenger compartment. Look for stains or wet spots on the bottom of the plastic HVAC case, or on the passenger side floor. Some Chrysler vehicles have a reputation for developing coolant leaks in the heater core, and repeat heater core failures. Some have found that an aftermarket copper/brass replacement heater core lasts longer in these applications than the original equipment aluminum heater core.</div>
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<b>Intake Manifold gasket</b> -- The gasket that seals the intake manifold to the cylinder heads may leak and allow coolant to enter the intake port, crankcase or dribble down the outside of the engine. Some engines such as General Motors 3.1L and 3.4L V6 engines as well as 4.3L, 5.0L and 5.7L V8s are notorious for leaky intake manifold gaskets. The intake manifold gaskets on these engines are plastic and often fail at 50,000 to 80,000 miles. Other troublesome applications include the intake manifold gaskets on Buick 3800 V6 and Ford 4.0L V6 engines.</div>
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INTERNAL COOLANT LEAKS</h3>
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There are the worst kind of coolant leaks for two reasons. One is that they are impossible to see because they are hidden inside the engine. The other is that internal coolant leaks can be very expensive to repair.</div>
<img alt="a bad head gasket can leak coolant" src="http://www.aa1car.com/library/elements/bad_head_gasket.gif" style="font-family: Arial;" /><br style="font-family: Arial;" /><br style="font-family: Arial;" /><b style="font-family: Arial;"></b><br />
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<b>Bad head gasket</b> --Internal coolant leaks are most often due to a bad head gasket. The head gasket may leak coolant into a cylinder, or into the crankcase. Coolant leaks into the crankcase dilute the oil and can damage the bearings in your engine. A head gasket leaking coolant into a cylinder can foul the spark plug, and create a lot of white smoke in the exhaust. Adding sealer to the cooling system may plug the leak if it is not too bad, but eventually the head gasket will have to be replaced.</div>
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If you suspect a head gasket leak, have the cooling system pressure tested. If it fails to hold pressure, there is an internal leak. A "block tester" can also be used to diagnose a leaky head gasket. This device draws air from the cooling system into a chamber that contains a special blue colored leak detection liquid. Combustion gases will react with the liquid and cause it to change color from blue to green if the head gasket is leaking.</div>
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Head gasket failures are often the result of engine overheating (which may have occurred because of a coolant leak elsewhere in the cooling system, a bad thermostat, or an electric cooling fan not working). When the engine overheats, thermal expansion can crush and damage portions of the head gasket. This damaged areas may then start to leak combustion pressure and/or coolant.</div>
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<img alt="cracks in cylinder head can leak coolant" src="http://www.aa1car.com/library/elements/cracked_cylinder_head.jpg" style="font-family: Arial;" /><span style="font-family: Arial;"> </span><i style="font-family: Arial;">A cracked cylinder head can leak coolant inside the engine.</i><br style="font-family: Arial;" /><b style="font-family: Arial;"></b><br />
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<b>Cracked Head or Block</b> -- Internal coolant leaks can also occur if the cylinder head or engine block has a crack in a cooling jacket. A combustion chamber leak in the cylinder head or block will leak coolant into the cylinder. This dilutes the oil on the cylinder walls and can damage the piston and rings. If the coolant contains silicates (conventional green antifreeze), it can also foul the oxygen sensor and catalytic converter. If enough coolant leaks into the cylinder (as when the engine is sitting overnight), it may even hydro-lock the engine and prevent it from cranking when you try to start it. Internal leaks such as these can be diagnosed by pressure testing the cooling system or using a block checker.</div>
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A coolant leak into the crankcase is also bad news because it can damage the bearings. Coolant leaking into the crankcase will make the oil level on the dipstick appear to be higher than normal. The oil may also appear frothy, muddy or discolored because of the coolant contamination.</div>
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<b>Leaky ATF oil cooler</b> -- Internal coolant leakage can also occur in the automatic transmission fluid oil cooler inside the radiator. On most vehicles with automatic transmissions, ATF is routed through an oil cooler inside the radiator. If the tubing leaks, coolant can enter the transmission lines, contaminate the fluid and ruin the transmission. Red or brown drops of oil in the coolant would be a symptom of such a leak. Because the oil cooler is inside the radiator, the radiator must be replaced to eliminate the problem. The transmission fluid should also be changed.</div>
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PRESSURE TESTING THE COOLING SYSTEM FOR LEAKS</h3>
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There are several ways to find out whether or not your cooling system is holding pressure. One is to top off your cooling system, tighten the radiator cap and start the engine. When the engine reaches normal operating temperature, turn on the air conditioner (to increase the cooling load on the system) and/or take it for a short drive. Then check the radiator, hoses and water pump for seepage or leaks.</div>
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<b><i>WARNING:</i></b><i> DO NOT open the radiator cap while the engine is hot!</i> Even if the cooling system is leaking, the coolant will be under considerable pressure -- especially if it is low and coolant is boiling inside the engine. Shut the engine off and let it sit about an hour so it can cool down. Then place a rag over the radiator cap and slowly turn the cap until it starts to release pressure. Wait until all the pressure has vented before turning the cap the rest of the way off.</div>
<img alt="radiator pressure tester" src="http://www.aa1car.com/library/elements/pressure_tester.jpg" style="font-family: Arial;" /><span style="font-family: Arial;"> </span><i style="font-family: Arial;">Radiator pressure test kit</i><br />
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A special tool called a pressure tester can also be used to check your cooling system. The tool is nothing more than a little hand pump with a combination vacuum-pressure gauge and a fitting that is attached to the radiator filler neck. To check for leaks, attach the tool to the radiator and pressurize the radiator to the pressure rating on the radiator cap. For example, if you have a radiator cap that says 12 pounds, you pressurize the radiator to 12 lbs. and wait to see what happens. If there are no leaks, the system should hold pressure for 10 to 15 minutes. If it does not hold pressure, the system is leaking. If you cannot see any visible leaks on the outside, it means the leak is inside (bad head gasket or cracked head or block). </div>
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A block Checker is another tool that can be used to detect a leaky head gasket. The gas-sensitive blue liquid changes color if there are any combustion gases in the coolant.</div>
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Leak detection dye can also be added to the coolant itself to make a slow leak easier to find. Some of these dyes glow bright green or yellow when exposed to ultraviolet light.</div>
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RADIATOR CAP CHECKS</h3>
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The radiator cap should also be pressure tested, especially if the system has been overheating or losing coolant with no obvious external leaks. A weak cap that cannot hold pressure will allow the system to boil over. If the cap cannot hold its rated pressure, replace it.</div>
<img alt="replace radiator to repair coolant leak" src="http://www.aa1car.com/library/elements/radiator_replace.jpg" style="font-family: Arial;" /><span style="font-family: Arial;"> </span><i style="font-family: Arial;">The best fox for a leaky radiator is to replace it with a new or recored radiator.</i><br />
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REPAIRING A LEAKY RADIATOR</h3>
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If your radiator is leaking, you have several repair options:</div>
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You can try the cheap fix and add a bottle of cooling system sealer to the radiator. These products are designed to seal small leaks. They can also seal internal engine leaks. Some work better than others, but most provide only a temporary solution to your problem.</div>
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You can attempt to repair the radiator yourself. Copper/brass radiators on older vehicles can often be soldered to repair leaks. Cracks or pinholes in aluminum radiators in newer vehicles can often be repaired with epoxy glue. But if the core is severely corroded or damaged, the radiator may have to be professionally repaired at a radiator shop, or replaced with a new radiator.</div>
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HOW TO FIX A LEAKY HEATER CORE</h3>
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As with a leaky radiator, you might try the cheapest fix and add a bottle of cooling system sealer to see if that will stop the leak. If the leak is small, the sealer will probably stop the leak - at least temporarily. But if the sealer does not stop the leak, you will have to disassemble the HVAC case to replace the heater core. This is a very time-consuming and difficult job that involves a LOT of labor on most vehicles. The labor to replace a heater core can often run 8 to 10 hours or more!</div>
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Some vehicles have had problems with repeat heater core failures (some Chrysler cars, for example). The problem in some cases is the design of the heater core itself, or the metal alloys from which it was made. But a common cause of heater core leaks is Electrolysis Corrosion. One fix is to attach a grounding strap on the heater core. Another is to replace an original equipment aluminum heater core with an aftermarket copper/brass heater core.</div>
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COOLANT RESERVOIR LEAKS</h3>
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Another cooling system component that sometimes needs attention is the coolant overflow reservoir. The coolant overflow reservoir does more than catch the overflow from the radiator. It serves as a storage tank for excess coolant. When the system is hot, coolant will be forced out through the radiator pressure cap and into the reservoir. Then as the system cools down, decreasing pressure will draw coolant back into the radiator.</div>
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On many newer vehicles, the coolant reservoir is pressurized and is an integral part of the cooling system. The filler cap for the cooling system is located on the reservoir tank, and the tank is connected to the radiator and engine with hoses. The reservoir is transparent plastic and you can see the coolant level inside.</div>
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If the coolant reservoir is cracked or leaking, the system may lose coolant every time the engine heats up. Eventually, this can cause the engine to overheat.</div>
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Small punctures or cracks in the overflow reservoir can usually be repaired with silicone sealer. If the reservoir needs to be replaced, make sure the hoses are routed correctly between the radiator and the reservoir, and that it is free from kinks that could block the flow of coolant back and forth.</div>
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HOW TO FIX A LEAKY FREEZE PLUG</h3>
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Freeze plus (also called expansion plugs) are round metal plugs that are pressed into cylinder head and engine block castings. The plug is supposed to push out and save the casting if the coolant does not contain enough antifreeze to prevent it from freezing during cold weather. Over time, the plugs can corrode from the inside and leak, causing the engine to lose coolant and overheat.</div>
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One way to temporarily patch a leaky freeze plug is to clean the surface of the plug, sand it lightly with sandpaper, and pack it solid with a high temperature two-part epoxy such as gas tank sealer or JB Weld epoxy. Let it cure overnight. This trick usually seals leaky expansion plugs that would otherwise be very difficult to replace.</div>
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To replace a leaky freeze plug, use a hammer and drift to knock out the old plug. Pounding in on one side of the plug will usually cause it to twist. The plug can then be pried out with a large screwdriver. Clean the hole, then apply a liberal coating of sealer to the hole and carefully drive in a new replacement plug. The plug must go in straight or it may not seal.</div>
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Another repair option is to replace a solid metal freeze plug with an expandable freeze plug. The expandable plugs have a rubber grommet that expands and seals against the opening when the center bolt in the plug is tightened. It's easier to install and less apt to leak than a solid plug.</div>
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HOW TO FIX A LEAKY COOLANT HOSE</h3>
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Do not waste your time trying to patch or wrap a leaky radiator or heater hose. Sealers and Stop Leak products also do not work well with hoses. Replace the bad hose with a new one, and inspect all the other hoses because if one has failed the others are probably reaching the end of the road, too.</div>
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Old hoses are often hard and stick to their fittings, making them difficult to remove. Use a razor blade or box cutter to slit the old hose so it can be easily pulled off its end fittings.</div>
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It is also a good idea to replace the original hose clamps, especially if they are the ring type. Ring clamps can lose tension with age and may not hold the hose tightly. Worm drive stainless steel clamps are best. But quality brand stainless steel worn drive clamps, not the cheap plain steel ones that are made in China. They will rust and fail.</div>
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You should also inspect the inside of your old radiator and heater hoses after they have been removed to check for deep fissures or cracks caused by Electrolysis Corrosion. This type of corrosion can be caused by old antifreeze that no longer provides adequate corrosion protection, or by stray electrical currents that use the coolant as a ground path.</div>
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HOW TO FIX A LEAKY WATER PUMP</h3>
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No Stop Leak or cooling system sealer product will seal a water pump that is leaking coolant past the shaft seal. Replacement is your only option. But you can save some money on the job by using a remanufactured water pump rather than a new water pump.</div>
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Replacing a water pump is not too hard a job on most engines, but on some it can be tricky. On some engines (2.8L GM V6 engines, for example), the bolts that hold the water pump also hold the timing cover in place. If you are not careful, the timing cover seal can be broken allowing coolant to leak into the crankcase. GM recommends using a special tool (J-29176 or equivalent) to hold the timing cover tight while the pump is being changed.</div>
<img alt="fan clutch" src="http://www.aa1car.com/library/elements/fan_clutch.jpg" style="font-family: Arial;" /><span style="font-family: Arial;"> </span><i style="font-family: Arial;">Check the fan clutch because a weak clutch can cause the engine to overheat.</i><br />
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If your engine has a belt-driven fan with a fan clutch, it is also a good idea to check the fan clutch when replacing the water pump. The lifespan of both is about the same, so the fan clutch may also need be replaced. If the clutch is leaking silicone fluid, or has any wobble in the bearing, it must be replaced.</div>
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REFILLING THE COOLING SYSTEM</h3>
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When refilling the cooling system after making a repair, always use a 50/50 mixture of antifreeze and water. Never use straight water because it has no freezing protection, no corrosion protection and it boils at a lower temperature (212 degrees F.) than a mixture of antifreeze and water (which protects to 240 degrees F.).</div>
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Use the type of antifreeze specified by the vehicle manufacturer, or a Universal Coolant that is compatible with all makes/models. Most late model vehicles require some type of OAT or HOAT long life coolant. GM vehicles use Dex-Cool.</div>
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On some late model front-wheel drive cars, refilling the cooling system can be tricky unless you "burp" the system by opening a bleeder vent or cracking a hose at a high point in the system to allow trapped air to escape. If you do not get all of the air out, the engine may overheat the first time you drive it.</div>
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The best way to refill the system is to add coolant until the radiator is within an inch of being full. Also add coolant to the coolant reservoir, filling it to the proper level. If the system has a pressurized coolant reservoir, add coolant until the level inside the reservoir is at the COLD FULL mark. Start the engine and let it idle with the radiator or coolant reservoir cap off until the thermostat opens and coolant starts to circulate through the engine. The heater should also be on so coolant will flow through the heater core. As the coolant level drops, continue to add coolant until the system takes no more. Then replace the radiator cap and drive a short distance. Shut the engine off, and after it has cooled recheck the coolant level once again. If low, add as needed.</div>
Anonymoushttp://www.blogger.com/profile/07884952301771193295noreply@blogger.com1tag:blogger.com,1999:blog-2529084104041640172.post-60739346514841993702017-01-09T06:54:00.000-08:002017-01-09T06:54:10.529-08:00Engine & Driveability Problems: 4 Engine Overheating<center style="font-family: Arial;">
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Engine Overheating</h1>
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Is your engine overheating? Most engines are designed to operate within a "normal" temperature range of about 195 to 220 degrees F. A relatively constant operating temperature is essential for proper emissions control, good fuel economy and performance. But problems can arise that cause the engine to run hotter than normal, resulting in engine overheating.</div>
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Your engine's cooling system is filled with a 50/50 mixture of water and ethylene glycol antifreeze. The coolant will boil at 225 degrees unless it is held under pressure by the radiator cap. A 15 PSI radiator cap will increase the boiling temperature of a 50/50 coolant blend up to 265 degrees F. If the concentration of antifreeze to water is upped to 70/30 (the maximum recommended), the boiling temperature with a 15 psi radiator cap goes up to 276 degrees. So obviously the radiator cap plays a significant role in preventing the coolant from boiling and the engine from overheating.</div>
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Anytime temperatures climb beyond the normal range, for any reason, your engine is in danger of overheating.</div>
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POSSIBLE CAUSES OF OVERHEATING</h3>
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Overheating can be caused by anything that decreases the cooling system's ability to absorb, transport and dissipate heat: A low coolant level, a coolant leak (through internal or external leaks), poor heat conductivity inside the engine because of accumulated deposits in the water jackets, a defective thermostat that doesn't open, poor airflow through the radiator, a slipping fan clutch, an inoperative electric cooling fan, a collapsed lower radiator hose, an eroded or loose water pump impeller, or even a defective radiator cap.</div>
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One of nature's basic laws says that heat always flows from an area of higher temperature to an area of lesser temperature, never the other way around. The only way to cool hot metal, therefore, is to keep it in constant contact with a cooler liquid. And the only way to do that is to keep the coolant in constant circulation. As soon as the circulation stops, either because of a problem with the water pump, thermostat or loss of coolant, engine temperatures begin to rise and the engine starts to overheat.</div>
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The coolant also has to get rid of the heat it soaks up inside the engine. If the radiator is clogged with bugs and debris, or if its internal passages are blocked with sediment, rust or gunk, the cooling efficiency will be reduced and the engine will run hot. The same thing will happen if the cooling fan is not engaging or spinning fast enough to pull air through the radiator.</div>
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The thermostat must be doing its job to keep the engine's average temperature within the normal range so the engine does not overheat. If the thermostat fails to open, it will effectively block the flow of coolant and the engine will overheat.</div>
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Exhaust restrictions can also cause the engine to overheat. The exhaust carries a lot of heat away from the engine, so if the catalytic converter is restricted, or a pipe has been crimped or crushed, exhasut flow can be restrricted causing heat to build up inside the engine.</div>
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It's also possible that your engine really isn't overheating at all. Your temperature gauge or warning lamp might be coming on because of a faulty coolant sensor. Sometimes this can be caused by a low coolant level or air trapped under the sensor.</div>
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POSSIBLE CONSEQUENCES OF ENGINE OVERHEATING</h3>
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If your engine is overheating, it may start to detonate. The engine may rattle and ping and lose power. If detonation continues, it may damage the rings, pistons and/or rod bearings.</div>
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Overheating can also cause pisto scuffing. As the engine gets hotter and hotter, the pistons may swell to the point where there is no more room for expansion and they scrape against the cylinders, damaging the pistons and cylinders.</div>
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Exhaust valves may also stick or scuff in their guides. This can damage the valves, guides and lead to a loss of compression.</div>
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Another consequence of engine overheating may be a blown head gasket. Heat makes aluminum swell almost three times faster than cast iron. Thermal stress can distort the head and make it swell in areas that are hottest like those between exhaust valves in adjoining cylinders, and areas that have restricted coolant flow like the narrow area that separates the cylinders. The typical aluminum head swells most in the middle, which can crush the head gasket if the head gets too hot. This will usually cause the head gasket to leak compression between adjacent cylinders, or leak coolant into the cylinders.</div>
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Engine overheating can also cause an overhead cam to seize and break.</div>
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Engine overheating may also stress old radiator and heater hoses and cause they to burst under the additional pressure. Steam that is generated inside the cooling system can also damage radiators with plastic end tanks.</div>
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A HOT warning lamp should never be ignored. Though a few high tech cars like Cadillacs with the Northstar engine can disable cylinders to "air-cool" the engine and keep it running at reduced power in the event of coolant loss, most engines will suffer serious damage if they overheat. So advise your customers to stop driving at the first sign of overheating. Turn the engine off, let it cool down and try to find and fix the cause before risking further travel.</div>
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WHAT TO CHECK<br />
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<img align="left" alt="engine thermostat" src="http://www.aa1car.com/library/elements/thermostat.gif" />* <b>Bad Thermostat</b> -- Severe engine overheating can often damage a good thermostat. If the engine has overheated because of another problem, therefore, the thermostat should be tested or replaced before the engine is returned to service.</div>
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One way to check the thermostat is to start the engine and feel the upper radiator hose (or use an infrared noncontact thermometer to read its temperature). The hose should not feel uncomfortably hot until the engine has warmed-up and the thermostat opens. If the hose does not get hot, it means the thermostat is not opening.</div>
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Another way to test the thermostat is to remove it and dip it into a pan of boiling water (it should open). The exact opening temperature can be checked by using a thermometer.</div>
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If the thermostat needs to be replaced, install one with the same temperature rating as the original. Most cars and light trucks since 1971 require thermostats with 192 or 195 degree ratings. Using a cooler thermostat (160 or 180) in an attempt to "cure" a tendency to overheat can increase fuel and oil consumption, ring wear and emissions. On newer vehicles with computerized engine controls, the wrong thermostat can prevent the computer system from going into closed loop resulting in major performance and emission problems if the engine fails to reach its normal operating temperature.</div>
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<b>TIP:</b> When refilling the cooling system, air can become trapped under the thermostat. This will form a steam pocket that prevents the thermostat from opening and may cause the engine to overheat. Some cooling systems have one or more bleeder valves that can be opened to vent air from the system while refilling the system. If your cooling system does not have a bleeder valve, you can drill a small hole in the thermostat as shown. This will allow air to escape past the thermostat so it is not trapped inside the engine block. Some thermostats come with a similar feature called a "jiggle valve." There is a small hole in the thermostat with a pin that allows air to escape.</div>
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* <b>Cooling system leaks</b> -- Loss of coolant because of a <a href="http://www.aa1car.com/library/coolant_leaks.htm">coolant leak</a> is probably the most common cause of engine overheating. Possible leak points include hoses, the radiator, heater core, water pump, thermostat housing, head gasket, freeze plugs, automatic transmission oil cooler, cylinder head(s) and block.</div>
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Make a careful visual inspection of your entire cooling system, and then PRESSURE TEST the cooling system and radiator cap. A pressure test will reveal internal leaks such as seepage past the head gasket as well as cracks in the head or block. A good system should hold 12 to 15 psi for 15 minutes or more with no loss in pressure. If it leaks pressure, there is an internal coolant leak (most likely a bad head gasket but possibly also a cracked cylinder or engine block).</div>
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It is important to pressure test the radiator cap, too, because a weak cap (or one with too low a pressure rating for the application) will lower the coolant's boiling point and can allow coolant to escape from the radiator.</div>
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<b>Leaky Head Gasket</b> -- Bad news because repairs are expensive. A leaky head gasket can allow coolant to seep into the engine's cylinders or crankcase. Symptoms include a loss of coolant with no visible external leaks, and white steam in the exhaust, especially after restarting the engine when it has sit for awhile. A leaky head gasket can be diagnosed by pressure testing the cooling system, or by using a "block checker" that pulls air from the cooling system into a cylinder that contains a special blue colored leak detection liquid. If there are any combustion gases in the coolant, the color of the liquid inside the detector will change from blue to green. A leaky head gasket can often be temporarily sealed by adding a sealer product to the cooling system. But for bad leaks or ones that cannot be stopped with sealer, the head gasket has to be replaced.</div>
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<b style="font-family: Arial;">Fan Not Working</b><span style="font-family: Arial;"> -- With mechanical fans, most engine overheating problems are caused by a faulty fan clutch</span><span style="font-family: Arial;">, though a missing fan shroud can reduce the fan's cooling effectiveness by as much as 50% (depending on the fan's distance from the radiator) which may be enough to cause the engine to overheat in hot weather or when working hard.</span><br />
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Defective fan clutches are a common and often overlooked cause of engine overheating. The shear characteristics of the clutch fluid gradually deteriorates over time, with an average loss in drive efficiency of about 200 rpm per year. Eventually slippage reaches the point where effective cooling is no longer possible and overheating results. (On average, the life of a fan clutch is about the same as a water pump. If one needs to be replaced, the other usually does too.)</div>
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If the fan clutch shows signs of fluid leakage (oily streaks radiating outward from the hub of the clutch), spins freely with little or no resistance when the engine is off, or wobbles when the fan is pushed in or out, it needs to be replaced.</div>
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With an electric cooling fan, check to see that the fan cycles on when the engine gets hot and when the air conditioner is on. If the fan fails to come on, check the fan motor wiring connections, fan relay and temperature sensor. Try jumping the fan directly to the battery. If it runs, the problem is in the wiring, relay or sensor. If it fails to run, the fan motor is bad and needs to be replaced.</div>
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With a hydraulic cooling fan, the fan must be turning fast enough to provide adequate cooling at idle and low speed.</div>
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<b>Leaky Water pump</b> -- Any wobble in the pump shaft or seepage would call for replacement. In some instances, a pump can cause an engine to overheat if the impeller vanes are badly eroded due to corrosion or if the impeller has come loose from the shaft. The wrong pump may also cause an engine to overheat. Some engines with serpentine drive belts require a special water pump that turns in the opposite direction of those used on the same engine with ordinary V-belts.</div>
<img alt="water pump erosion" src="http://www.aa1car.com/library/elements/waterpump_erosion.jpg" style="font-family: Arial;" /><span style="font-family: Arial;"> </span><i style="font-family: Arial;">Cavitation damage inside a water pump</i><br />
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It does not happen very often, but sometimes the water pump impeller can loosen up on the pump shaft and not turn, although the water pump pulley appears to be turning normally. If the impeller does not spin, there will be little or no circulation of coolant through the engine. The only way to know if this is the problem is to remove the water pump and check the impeller to see that is is tight on the shaft. Also, some plastic impellers can become severely eroded over time. The water pump housing and/or impeller may also experience cavitation erosion. The loss of blade area or an increase in clearance between the housing and impeller will reduce the flow of coolant and can lead to engine overheating.</div>
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<b>Slipping Belt</b> -- Check belt tension and condition. A loose belt that slips may prevent the water pump from circulating coolant fast enough and/or the fan from turning fast for proper cooling.</div>
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<b>Lower Radiator Hose Collapsing</b> -- A pinched hose (upper or lower) or a lower radiator hose that is collapsing and blocking the flow of coolant when the engine is running can cause engine overheating. The lower hose usually has a metal reinforcing wire inside that looks like a large spring. It s purpose is to prevent the hose from collapsing when the water pump is pulling water through the hose. If this wire is missing or has failed due to corrosion, the hose may collapse.</div>
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<b>Plugged or Dirty Radiator</b> -- Dirt, dead bugs and debris can block air flow through the radiator and reduce its ability to dissipate heat. Internal corrosion and an accumulation of deposits can also block the flow of coolant. A good way to find internal clogs is to use an infrared thermometer to "scan" the surface of the radiator for cold spots. If clogged, the radiator should be removed for cleaning or replaced. Backflushing the cooling system and/or using chemical cleaners can remove rust and hard water scale, but may do little to open up a clogged radiator.</div>
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When refilling the cooling system, be sure you get it completely full. Air pockets in the head(s), heater core and below the thermostat can interfere with proper coolant circulation and cooling. If the cooling system has no bleeder valves to vent air, you may have to temporarily loosen a heater hose to get all the air out of the system.</div>
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<b>Excessive exhaust backpressure</b> -- A clogged catalytic converter will restrict the flow of exhaust and cause heat to back up in the engine. Other causes include a crushed exhaust pipe or a collapsed double wall pipe. Check intake vacuum at idle. If intake vacuum reads low and continues to drop, inspect the exhaust system.</div>
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<b>Overheated incoming air</b> -- On older vehicles with a carburetor or throttle body injection, check the operation of the heated air intake system on the air cleaner. If the temperature control valve is stuck so only heated air from around the exhaust manifold is drawn into the air cleaner, it may contribute to detonation and/or engine overheating. Also check the heat riser valve for manifold heat on older V6 and V8 engines. If stuck shut, it may be overheating the intake manifold.</div>
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<b>Dragging brakes</b> -- A disc brake caliper that is sticking or a parking brake that is not releasing may be making your engine work harder than normal to overcome the friction. Check the brakes and fix as needed.</div>
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<b>Overworking the engine</b> -- The cooling systems in many passenger cars today are marginal and have little excess capacity to handle extra heat generated by towing or high speed mountain driving in hot weather. Replacing the original stock radiator with a larger or thicker radiator can improve cooling capacity.</div>
Anonymoushttp://www.blogger.com/profile/07884952301771193295noreply@blogger.com0tag:blogger.com,1999:blog-2529084104041640172.post-52462389821330385872017-01-09T06:00:00.003-08:002017-01-09T06:00:55.651-08:00Engine & Driveability Problems: 3 Engine Temperature Warning Light<center style="font-family: Arial;">
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Engine Temperature Warning Light</h1>
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<b>Should You Continue Driving If Your Temperature Warning Light is On?</b></center>
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Driving with the temperature warning light on can increase the risk expensive engine damage! When the temperature light comes on, it means your engine is overheating (running too hot). An engine should not overheat if the cooling system is properly filled and is working normally -- even during hot weather or stop-and-go driving. Sometimes abnormal driving conditions such</div>
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as towing a heavy trailer during hot weather may overload the cooling system's capacity to control heat, but usually, a temperature warning light means trouble.</div>
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What To Do If Your Temperature Warning Light Comes On</h3>
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<b><i>STOP DRIVING IMMEDIATELY!</i></b>. Pull over to the side of the road as soon as it is safe to do so, then shut off your engine and wait for things to cool down.</div>
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<i><b>WARNING: Do NOT attempt to open the radiator cap!</b></i> The radiator contains hot water under high pressure. Opening the cap on the radiator or a pressurized coolant reservoir could allow steam and water to blow out and burn you. There's nothing to be accomplished by opening the cap while the engine is still hot, so let your vehicle sit and cool off.</div>
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After things have cooled down (wait at least half an hour or more), then you can open the radiator cap or reservoir and check the coolant level. Place a rag over the cap first, and slowly turn the cap until it stops at the first detent. This should allow residual pressure to be released. Wait until all pressure has been released before removing the cap the rest of the way.</div>
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Add water or coolant to the radiator or coolant reservoir if it is low. Actually, you should add premixed coolant or a 50/50 mixture of antifreeze and water to maintain the proper freezing, boil over and corrosion protection. But in most cases when this happens, it's an emergency situation and you won't have a jug of antifreeze handy. If that's the case, add water now, then drain out some of the coolant later and offset the extra water by adding the proper amount of antifreeze.</div>
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Check for Coolant Leaks</h3>
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Your engine may have overheated because of a coolant leak. Visually inspect the radiator, engine and cooling system for leaks. Common leak points include radiator and heater hoses, hose connections, the water pump and radiator. Internal leaks (such as a crack in the head or engine) can't be seen and can only be diagnosed by pressure testing the cooling system.</div>
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IF YOU DON'T STOP DRIVING...<br />
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If you keep driving an engine that is overheating, it can cause serious damage. The engine may start to knock (caused by detonation), which in turn can cause piston, ring, and head gasket damage. As the internal parts of the engine expand from the excessive heat, clearances may be reduced to the point where metal-to-metal contact occurs. Valve stems may gall and stick, and the pistons and camshaft might scuff or seize.</div>
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Severe engine overheating also creates tremendous thermal stress in the head(s) and block. This, in turn, may lead to cracking and/or warpage. This is a common problem with overhead cam engines that have aluminum heads.</div>
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The only vehicle that can be "safely" driven when the temperature warning light is on a late model Cadillac with a Northstar V8 engine. Cadillac engineers designed the engine control system to automatically deactivate half of the engine's cylinders if it senses an overheating problem. This reduces the heat (and power) being generated by the engine, and it allows the "dead" cylinders to pump air through the engine for internal cooling. The system is designed to provide a "limp-in" mode so the vehicle can be driven to the nearest service facility or Cadillac dealer for repairs. It is not designed for continuous driving.</div>
Anonymoushttp://www.blogger.com/profile/07884952301771193295noreply@blogger.com0tag:blogger.com,1999:blog-2529084104041640172.post-65246687684274572032017-01-09T05:55:00.005-08:002017-01-09T05:55:41.670-08:00Engine & Driveability Problems: 2 Engine Oil Pressure Warning Light On<center style="font-family: Arial;">
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Engine Oil Pressure Warning Light On</h1>
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<img align="left" alt="engine oil pressure warning light" src="http://www.aa1car.com/library/warning_light_oil.gif" />If the engine oil pressure warning light is on, it may mean your engine has lost normal oil pressure. STOP driving immediately and turn the engine off. The engine can be severely damaged if oil pressure is lost.</div>
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<b>Possible Causes of Low Oil Pressure Warning Light:</b></div>
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A low oil level (check the dipstick), bad oil pump, or defective oil pressure sending unit, oil pressure gauge or warning light switch.</div>
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Oil Pressure Warning Light Diagnosis</h3>
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First, determine if the oil is full or low by checking the dipstick. NOTE: On some engines, there is an oil level sensor in the engine's oil pan that will turn on the oil warning light if the oil level is low. If the dipstick shows a low oil level (the oil level is at or below the ADD line, or no oil can be seen on the dipstick), your engine may be leaking oil, burning oil or both.</div>
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Oil leaks are a common cause of oil consumption and a low oil level in the engine. Oil leaks can occur at the valve cover, oil pan or timing cover gaskets, or the front and rear crankshaft oil seals. Inspect the top, sides and bottom of the engine for signs of oil leakage. Look for greasy stains, heavy accumulations of grease, or oil dripping on the ground. The higher the miles on the engine, the more likely the gaskets and seals may be leaking. If your engine is leaking oil because of a bad gasket or seal, the leaky gasket or seal should be replaced.</div>
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If the outside of the engine is clean and there are no obvious oil leaks, and the oil level is low, the engine is probably burning oil due to worn piston rings, valve guides or valve guide seals. This may be the result of high mileage wear or neglect. Either way, this kind of oil consumption problem is expensive to fix because it may require rebuilding or replacing the engine. <b>NOTE:</b> On many engines, replacing the valve guide seals will significantly reduce oil burning if the original guides and seals are worn.</div>
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If the oil usage is not too severe (say less than one quart of oil every 1000miles), check the dipstick often and keep adding oil as needed. If the engine is using a lot of oil (say more than a quart every 500 miles), check the dipstick constantly and keep plenty of oil on hand. An engine that is burning a lot of oil is worn out and will soon have to be overhauled or replaced.</div>
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Bad Oil Pump?</h3>
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If the oil level is between ADD and FULL, and the engine was making noise when it was running, the problem may be a bad oil pump. DO NOT run the engine until the problem can be repaired. Oil pressure can be checked by attaching a pressure gauge to the engine where the oil pressure sending unit is attached. If oil pressure is within specifications (typically 10 psi for every 1000 rpm) the oil pump is okay. If pressure is less than specifications, the oil pump may be worn, or the engine bearings may be worn.<br /><br />If the oil level is between ADD and FULL, and the engine was running normally (no noise) after the oil pressure warning light came on, the problem may be a defective oil pressure sending unit, oil pressure gauge or warning light switch. You can probably start the engine and drive the vehicle home or to a shop for repairs. But if the engine starts to become noisy, STOP and shut off the engine.</div>
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Low Oil Pressure Fixes</h3>
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If the oil level is low, add oil to the engine to bring the level up to the FULL mark on the dipstick. DO NOT overfill the crankcase. Use the type of oil viscosity specified in the vehicle owners manual.</div>
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If the oil pressure gauge reading remains low or the oil pressure warning light remains on, remove the oil pressure sending unit on the engine and connect a pressure gauge directly to the engine. Start the engine to see if the pump is generating adequate pressure. If pressure is normal (about 10 PSI for every 1000 RPMs of engine speed, the problem is not a bad oil pump, but a faulty oil pressure sending unit. Replace the oil sending unit.</div>
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If you do not have a pressure gauge for testing oil pressure, try replacing the oil pressure sending unit with a new one. If the oil pressure warning light goes out or the gauge reading is now normal, you have fixed the problem. But if the warning light or low gauge reading continues, the problem is likely a bad oil pump.</div>
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If the oil pump is bad (does not produce adequate pressure), the oil pump will have to be replaced. On many engines, the oil pump is located inside the oil pan on the bottom of the engine. The pan must be removed to replace the pump. This may require raising the engine and/or removing steering or suspension components that are in the way so the pan can be removed. On other engines, the oil pump is located inside the timing cover on the front of the engine. Disassembly requires removing most of the components on the front of the engine to access the pump. This type of pump is much more difficult and time consuming to replace.</div>
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If oil pressure is low because of worn engine bearings, the crankshaft bearings will have to be replaced. This usually requires overhauling or replacing the engine.</div>
Anonymoushttp://www.blogger.com/profile/07884952301771193295noreply@blogger.com0tag:blogger.com,1999:blog-2529084104041640172.post-43930077974699466402017-01-09T05:53:00.000-08:002017-01-09T05:53:02.087-08:00Engine & Driveability Problems: 1 Check Engine Light On<center style="font-family: Arial;">
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Check Engine Light On</h1>
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The Check Engine Light (which is actually the Malfunction Indicator Lamp or MIL) alerts you when an emissions-related problem occurs with the engine control system or emission controls on your vehicle. Depending on the nature of the problem, the Check Engine Light may come on and remain on continuously or flash. Some intermittent problems will make the Check Engine Light come on only while the fault is occurring (such as engine misfire). The Check Engine light usually remains on once a fault has been detected, and will remain on to remind you that a problem has occurred that needs to be investigated.</div>
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An illuminated Check Engine Light can be annoying because you don't know what's wrong, and whether or not the problem might be a serious one or just a minor fault. There is no way to know what the problem is until you plug a scan tool into the vehicle's diagnostic connector and read out the code(s) that turned the light on.</div>
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If no other warning lights are on, and the engine seems to be running normally (no unusual noises, smells, vibrations, etc.), you can assume the fault that is causing the Check Engine Light to come on is probably minor and won't hinder your ability to continue driving. But if other warning lights are on, you should probably stop and investigate the problem.</div>
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When the Check Engine Light comes on, a diagnostic trouble code (DTC) is recorded in the powertrain control module (PCM) memory that corresponds to the fault. Some problems can generate more than one trouble code, and some vehicles may have multiple problems that set multiple trouble codes.</div>
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CHECK ENGINE LIGHT ON SETS TROUBLE CODES</h3>
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In most older vehicles (those made before 1996), disconnecting the computer's power source or disconnecting a battery cable erases fault codes and turns off the Check Engine Light, at least temporarily. If the problem persists, the code will reset and the Check Engine Light will come back on. But on many newer vehicles, you do NOT want to disconnect the battery because doing so can wipe out the computer's memory settings. This may affect the operation of the transmission, climate control system, and other functions.</div>
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In 1996 and newer vehicles, a scan tool or code reader must be used to erase codes and turn the Check Engine Light off.</div>
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<img alt="scantool check engine light on" height="250" src="http://www.aa1car.com/library/scantool_check_engine_light_on.jpg" /> </div>
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HOW TO READ FAULT CODES WITH A SCAN TOOL</h3>
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If your Check Engine light is on, you need to read the code(s) that are causing it to come on with a code reader or scan tool. Plug the tool into the 16-pin OBD diagnostic connector (usually located under the dash near the steering column).</div>
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When the ignition is turned on (don't start the engine yet), the tool will communicate with the PCM. You may be asked to enter the year/make/model and VIN code of your vehicle if the scan tool does not automatically recognize the application. Choose the READ FAULT CODE option on the scan tool menu, or press the button that allows the tool to read the codes. The tool will then display a number and/or code description that corresponds to a particular fault code. The letter "P" is the designation for Powertrain codes (which includes all of the engine controls, related emission controls, catalytic converter and fuel tank vapor control system). If there are more than one code, the codes will be listed in numeric order.</div>
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<b>TIP:</b> Write the code(s) down on a piece of paper before you erase them. You may need to refer to the codes again later if the same problem keeps returning. Erasing the codes will turn the Check Engine Light off, but sooner or later the codes will likely return and turn the Check Engine Light back on again if the problem is still there.</div>
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<b><i>Important!</i></b> A fault code will tell you which sensor or system experienced some kind of problem. But the code will NOT tell you why the fault occurred, how bad the fault is or which part to replace. That usually requires more advanced diagnostics.</div>
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CHECK ENGINE LIGHT ON DIAGNOSTICS</h3>
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Prior to OBD II, fault detection was mostly limited to "gross failures" within individual circuits or sensors. The first generation systems were not capable of detecting misfire, converter problems or fuel vapor leaks. OBD II changed all of that by adding the ability to monitor these things so emission problems can be detected as they develop.</div>
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OBD II uses the Check Engine Light to alert the driver when a fault occurs, and it stores trouble codes that correspond to specific kinds of problems. It can also track problems as they develop and even capture a snapshot of sensor data when a problem occurs.</div>
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Almost any emission problem that causes hydrocarbon emissions to exceed 1.5 times the federal limit can cause the Check Engine Light to come on with OBD II, even if there is no noticeable driveability problem accompanying the emission problem.</div>
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OBD II not only monitors the operation of all the engine's sensors and systems (fuel, ignition, EGR, evaporative emissions, etc.), it also monitors the operation of the catalytic converter and can even detect engine misfires! Anything that could possibly affect emissions is monitored by OBD II, including a loose gas cap! </div>
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UNDERSTANDING DIAGNOSTIC TROUBLE CODES</h3>
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A misfire will cause the Check Engine Light to flash while the misfire is occurring. A misfire that occurs in a given cylinder will also set a P030X code where "X" will be the number of the cylinder that is misfiring. For example, a P0302 code would tell you cylinder number two is misfiring. Remember, the code does not tell you why the cylinder is misfiring. You have to figure that out by performing other diagnostic tests. The misfire might be due to a fouled spark plug, a bad plug wire, a defective ignition coil in a DIS ignition system, a clogged or dead fuel injector or a loss of compression due to a leaky exhaust valve, leaky head gasket or worn cam lobe.</div>
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OBD II monitors the operating efficiency of the catalytic converter with a second oxygen sensor in the tailpipe behind the converter. By comparing upstream and downstream O2 sensor readings, it can determine how well the converter is doing its job. If converter efficiency drops below a certain threshold, OBD II will set a code and turn on the Check Engine Light.</div>
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OBD II can detect fuel vapor leaks (evaporative emissions) in the charcoal canister, evap plumbing or fuel tank by pressurizing or pulling a vacuum on the fuel system. If the gas cap is loose or missing, it will detect it, set a code and turn on the Check Engine Light.</div>
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In addition, OBD II can also generate codes for various electronic transmission problems and even air condition failures such as a compressor failure.</div>
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TWO KINDS OF FAULT CODES</h3>
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OBD II is capable of generating two types of diagnostic trouble codes: "Generic" or "Global" codes (P0) that are the same for all makes and models of vehicles (these are required by law), and "Enhanced" or "OEM" codes (P1) that are unique to specific vehicles. Enhanced codes can also cover non-emission related failures that occur outside the engine control system. These include ABS codes, HVAC codes, airbag codes and other body and electrical codes.</div>
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The "generic" codes that are common to all vehicle manufacturers can be accessed using any basic code reader or scan tool that is OBD II compliant. Unfortunately, most older scan tools made before 1995 won't work on 1996 and newer vehicles with OBD II. You need a scan tool that has the proper hardware and software to talk to your onboard computer so it can read OBD II codes and other diagnostic information. In fact, a scan tool or code reader is required to read codes on most 1996 and newer vehicles because most newer vehicles do not have manual flash codes. There are some exceptions. Some Nissan models still provide manual flash codes, as do some Dodge models. Most GM, Ford, Honda and Toyota models do not have flash codes, but on some GM vehicles with a driver information display, there may be a procedure for displaying codes manually.</div>
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A simple code reader that plugs into the vehicle diagnostic connector can usually be purchased at an auto parts store for under $60. A basic scan tool that can read codes and additional system data (and erase codes) may sell for $70 to $400 depending on its features. The kind of scan tools that professional technicians use can cost several thousand dollars and have more advanced features, including bidirectional capabilities that allow the scan tool to run various self-tests that are built into the engine management system on your vehicle. These types of advanced tests may be required for more difficult-to-diagnose problems. The high end professional level scan tools can also graph sensor voltages, allowing them to reveal diagnostic data that a simple DIY scan tool cannot.</div>
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If you do not have a code reader or scan tool, you will have to take your vehicle to a repair facility or auto parts store if you need to diagnose a Check Engine Light problem.</div>
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Money Saving Tip: Some parts stores (such as AutoZone and others) will do a FREE plug-in diagnosis for you, or they will loan you a scan tool so you can do the basic diagnosis yourself in the parking lot. The scan tool will tell you what the codes are that turned on your Check Engine Light. Just remember that a code by itself does NOT tell you which part may need to be replaced. Additional diagnostic tests are usually needed to determine the underlying cause that set the code.</div>
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For example, a P0300 Random Misfire Code means the engine is misfiring in multiple cylinders but it doesn't tell you why it is misfiring. The cause could be fuel, ignition or compression, or any combination thereof. Additional tests are needed to identify the cause of the misfire.</div>
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YOUR VEHICLE WILL NOT PASS AN OBD PLUG-IN EMISSIONS TEST WITH A CHECK ENGINE LIGHT ON</h3>
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If your Check Engine Light is on, your vehicle will NOT pass an OBD plug-in emissions test. So if you are required to take such a test, the light must be out and there must be no codes in the PCM memory. You can't just erase the codes, drive your vehicle to the test station and take the test if the original problem is still there. The OBD II monitors need time to set, which usually requires driving at various speeds, sometimes over a period of several days. The OBD plug-in test checks to see if all of the monitor self-tests have completed, and if they have not your vehicle is rejected for not being ready.</div>
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The OBD plug-in test also determines if your Check Engine light is functioning properly. if the lamp is burned out or has been disabled, your vehicle will be rejected until the bulb is replaced or the problem has been fixed.</div>
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If the test finds any DTCs (Diagnostic Trouble Codes), your vehicle will fail the emissions test. The test center should give you a print out that lists any codes found along with possible suggestions as to what may be causing the fault(s). You must then have your vehicle repaired (which you can do yourself if you have the tools and know-how to do) or you can take it to a repair shop or new car dealer to have the problem fixed.</div>
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Anonymoushttp://www.blogger.com/profile/07884952301771193295noreply@blogger.com1tag:blogger.com,1999:blog-2529084104041640172.post-51149046944446444072017-01-07T09:52:00.002-08:002017-01-07T09:52:14.155-08:005 Vehicle Noises Not to Ignore!<center style="font-family: Arial;">
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<b style="font-family: Arial;"><span style="font-size: large;">Chirping or Squealing Sound From a Wheel While Driving</span></b></h1>
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A cyclic chirping or squealing noise coming from the vicinity of a wheel often indicates a wheel bearing or axle bearing that is failing. Usually the noise will change with the speed of the vehicle, and it may come and go at various speeds. This noise should not be ignored because if the bearing fails, it may cause the wheel to lockup or come loose from your car!</div>
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Don't confuse wheel bearing noise with scraping, groaning or creaking noises that may be coming from the brakes. During damp weather, moisture causes the brake pads to swell slightly. This may cause the pads to drag slightly, creating annoying groaning or creaking noises until the pads heat up and dry out.</div>
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A clicking noise from a front wheel that is only heard while turning usually indicates a bad outer constant velocity joint that is failing.</div>
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<b><span style="font-size: large;">Metallic Scraping or Grinding Noise When Braking</span></b></div>
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Brakes sometimes make groaning or creaking noises when the pads are damp, and some types of brake pads (particularly semi-metallic pads) may squeal or squeak when they are cold. But as a rule, the brakes should be relatively quiet when they are applied. If you hear metallic scraping or grinding noises when braking, it probably means your brake pads are worn out and your vehicle needs a brake job now. Don't delay because worn brakes may not be able to stop you vehicle in a safe distance. In fact, if the brakes are that badly worn, there is a risk the friction material that's left on the pads may separate from the backing plate, possibly causing the brakes to fail. Metal-to-metal contact is also very damaging to the rotors.</div>
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<b><span style="font-size: large;">Hissing Sound from Engine Compartment While Driving or After Driving</span></b></div>
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If you hear a hissing sound from the engine compartment while driving or after turning the engine off, it may mean your engine is overheating and/or leaking coolant from the cooling system. Check the temperature gauge or temperature warning light to see if it indicates a overheating condition. Do not continue driving (especially if you see steam) as severe overheating can damage your engine.</div>
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Stop your vehicle and carefully open the hood. Look for any evidence of coolant leaking from the engine, radiator, radiator or heater hoses. If you see steam or smell a sweet odor, it is antifreeze leaking from the cooling system. Do NOT open the radiator or coolant reservoir cap until the engine has cooled down, and do not add coolant until the engine has cooled.</div>
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Note: Adding coolant to a leaking cooling system won't accomplish much because the coolant will leak back out. Adding a can of cooling system sealer such as Bars Leak or a similar product may slow or stop a small leak, but a large leak, leaking water pump or hose will continue to leak even with sealer in the system. The leaky part needs to be replaced.</div>
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Engines can produce a lot of noises, but a metallic tapping or clicking sound means your engine may be low on oil, or is not developing normal oil pressure. The clicking noise is coming from the valvetrain. If oil pressure is low because of a low oil level in the crankcase or a problem with the oil pump, the hydraulic lifters that open and close the valves may collapse creating an increase in valve lash. This is the noise you hear, and it will be coming from the vicinity of the valve covers on top of the engine.</div>
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Stop the engine, let it sit a few minutes (so the oil can run back down into the crankcase), then check the oil level on the dipstick. If low, add oil as needed to bring the level back up to the full mark. Do not overfill the crankcase with oil. Also, check the engine for oil leaks. Old valve cover and pan gaskets, or leaky crankshaft end seals can allow oil to leak out of the engine.</div>
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If the noise does not go away, and/or the oil pressure gauge or warning light indicates low oil pressure, it's not a good idea to keep driving your vehicle. Loss of oil pressure can cause extensive and expensive engine damage.</div>
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Other engine sounds can also mean bad news. A deep metallic rapping noise can be caused by worn connecting rod bearings, and may indicate your engine has reached the end of the road (or will soon!).</div>
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If you hear a metallic knocking or clattering noise that only occurs while accelerating or when driving up a steep hill or pulling a load, your engine is likely experiencing detonation, a potentially damaging form of erratic combustion. Detonation can be caused by a buildup of carbon in the combustion chambers, low octane fuel, engine overheating, an EGR system that is not working, over advanced ignition timing, or a defective knock sensor.</div>
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<b><span style="font-size: large;">Exhaust Roar While Driving</span></b></div>
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If your exhaust system has a leak, you will hear exhaust noise coming from under your vehicle that is loudest when accelerating. The noise by itself won't hurt anything, but it does mean your exhaust system needs repairs (probably a new muffler or pipes). The dangerous part is if the leaking exhaust gases, which contain carbon monoxide, get inside the passenger compartment. Carbon monoxide (CO) is a silent killer. It takes only a small amount of carbon monoxide inside the passenger compartment to affect your alertness, ability to concentrate and react to changing driving conditions. As little as 0.08 percent carbon monoxide (that's only 800 parts per million) can cause dizziness, headaches, nausea, and bring on stupor in two hours. A one percent concentration of carbon monoxide can kill a person in less than three minutes!</div>
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You should have your exhaust system inspected and repaired as soon as possible, especially during cold weather when the windows are rolled up and the heater may be recirculating the air inside the passenger compartment. Exhaust components that typically leak include the exhaust manifold gaskets, cracks in the exhaust manifold, exhaust pipe connections, pipes that rust through, and mufflers that rust out.</div>
Anonymoushttp://www.blogger.com/profile/07884952301771193295noreply@blogger.com0tag:blogger.com,1999:blog-2529084104041640172.post-59367353970465537732017-01-07T09:50:00.001-08:002017-01-07T09:50:00.890-08:005 Vehicle Warning Light you should not ignore!<br />
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OIL PRESSURE WARNING LIGHT</h3>
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<img align="left" src="http://www.aa1car.com/library/warning_light_oil.gif" />The oil pressure warning light comes on if your engine has lost oil pressure or oil pressure is too low for safe engine operation. You should pull over to the side of the road, shut the engine off and check the oil level on the engine dipstick.</div>
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<b>Possible Causes:</b> Low oil level (due to oil consumption or leaks), oil viscosity too thin, worn oil pump, excessive engine bearing clearances or defective oil pressure sending unit.</div>
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If your engine is also making ticking, clattering or rapping noises, it is not getting sufficient oil. If you attempt to drive the engine in this condition, you will probably damage it - if it hasn't already suffered major internal damage.</div>
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TEMPERATURE WARNING LIGHT</h3>
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<img align="left" src="http://www.aa1car.com/library/warning_light_temp.gif" />The temperature warning light will come on if your engine is overheating. Do NOT continue driving if your engine is overheating as this can cause expensive engine damage (piston scuffing, valve stem galling, failed head gasket, cracks or distortion in cylinder head). Stop driving, pull over and shut your engine off. Open the hood and check the radiator and heater hoses, radiator and engine for coolant leaks. Note the level of the coolant in the coolant reservoir.</div>
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<b>CAUTION</b>: DO NOT open the coolant reservoir or radiator cap until the engine has cooled off for at least 30 minutes. Steam pressure inside the cooling system can blow out and burn you!</div>
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If the coolant level is low, add coolant (a 50/50 mixture of antifreeze and clean distilled water) after the engine has cooled down.</div>
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<b>Possible Causes:</b> Low coolant level (due to coolant leak or bad head gasket), stuck thermostat, bad water pump, broken serpentine belt, defective radiator cooling fan, clogged or dirty radiator, exhaust restriction (plugged catalytic converter).</div>
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HINT: Turning the A/C OFF and turning the heater on HIGH may help cool down an engine that is temporarily overheating due to unusually hot weather or from towing a trailer. But if the engine is running hot because it is low on coolant, this trick probably won't help much.</div>
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For more information about troubleshooting an overheating problem.</div>
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CHARGING SYSTEM WARNING LIGHT</h3>
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<img align="left" src="http://www.aa1car.com/library/warning_light_battery.gif" />The "GEN" or "ALT" warning light, or an icon of a battery will illuminate if the charging voltage in your vehicle is low. You do not have to stop immediately, but you may only have 20 to 30 minutes of driving time before your battery goes dead and your engine stops running (or even less time if you are driving at night with your headlights on).</div>
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<b>Possible Causes:</b> Broken or slipping serpentine belt or V-belt, bad alternator, charging control fault, or loose or corroded battery cables.</div>
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Open the hood to see if the drive belt that turns the alternator is intact and is turning the alternator while the engine is idling. If the belt is not the problem, chances are the charging system has a problem that will have to be diagnosed and repaired. Better find a repair shop soon!</div>
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For more information about the operation of the charging system and charging diagnosis.</div>
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BRAKE WARNING LIGHT</h3>
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<img align="left" src="http://www.aa1car.com/library/warning_light_brake.gif" />The Brake Warning light will come on if the parking brake has not been fully released, but it may also come on if the brake fluid level is low or there has been a loss of hydraulic pressure in one of your car's brake circuits. Loss of fluid or brake pressure means the brakes may not be able to stop your car when you step on the pedal.</div>
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Carefully apply the brakes to see if they are working. If they are, pull over to the side of the road, open the hood and check the fluid level in the brake master cylinder. If the fluid level is low, the brake system should be inspected for leaks. If there are leaks, your brake system is unsafe to drive.</div>
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If the brake pedal is low or goes to the floor, pumping the pedal may apply enough pressure to stop your car. If that fails, apply your parking brake to slow your vehicle. Also, take your foot off the gas and shift to neutral, or downshift and use engine braking to slow your vehicle if you have a manual transmission. If all that fails, aim for something soft like a brush or open field.</div>
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<b>Possible Causes:</b> Loss of brake fluid due to leaks (master cylinder, calipers, wheel cylinders, brake lines or hoses), failure of the pressure differential switch that activates the brake light, parking brake pedal or handle not fully releasing, defective parking brake switch.</div>
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<b>WARNING:</b> If the brake pedal feels soft, is low, goes to the floor, or you have to pump the pedal to get your vehicle to stop, your vehicle is unsafe to drive. You should have it towed to a repair facility for repairs.</div>
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LOW TIRE WARNING LIGHT</h3>
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<img align="left" alt="low tire pressure warning light" src="http://www.aa1car.com/library/tpms_icon.jpg" height="60" />The Low Tire Pressure Warning Light will come on if any tire on your vehicle is 25 percent or more underinflated. Driving on a low tire can be dangerous because it increases the risk of a tire blowout. A low tire can also cause uneven braking, uneven traction, uneven and rapid tire wear, increased rolling resistance and fuel consumption.</div>
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Find a gas station with an air pump, and check the inflation pressure in each tire with an accurate gauge (not the gauge on the pump, which is often very inaccurate!). Add air as needed to inflate your tires to the recommended pressure (see your owners manual or the tire inflation decal in the door jam or glove box). For most passenger cars, the recommended pressure is typically 32 to 34 PSI.</div>
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<b>Possible Causes:</b> Loss of air pressure due to a leak (such as a nail or small puncture in a tire, or a bad valve stem), loss of air pressure due to seepage (1 to 2 PSI per month loss is normal for many tires), or inaccurate or failing TPMS sensor in tire.</div>
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Checking your tires regularly (at least once a month or before any long road trip) is recommended. Check the tires when they are COLD and BEFORE you drive your vehicle as driving creates friction and heats up the tires (causing an increase in air pressure).</div>
Anonymoushttp://www.blogger.com/profile/07884952301771193295noreply@blogger.com0tag:blogger.com,1999:blog-2529084104041640172.post-64635282650765712292017-01-06T23:47:00.006-08:002017-01-06T23:47:58.871-08:005 Things Your Vehicle May Not Need<center style="font-family: Arial;">
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<b style="font-family: Arial;"><span style="font-size: large;">Tune-up </span></b><span style="font-family: Arial;"><span style="font-size: large;">-</span> The tune-up has been obsolete for decades. On late model</span><span style="font-family: Arial;"> </span><span style="font-family: Arial;">vehicles with computerized engine controls, there is nothing to "tune" or manually adjust. Major engine functions such as idle speed, the fuel mixture and spark timing are all controlled electronically by the powertrain control module</span><span style="font-family: Arial;">. In spite of this, many people still call changing their spark plugs and air filter a tune-up, when in fact what they are actually doing is scheduled preventive maintenance. Platinum and iridium spark plugs typically last upwards of 100,000 miles, and air filters can often go several years or 30,000 miles or more depending on driving conditions and dust exposure.</span><br />
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<span style="font-size: large;"><b>Chassis Lubrication</b> -</span> Some trucks may have grease fittings on the ball joints, tie rod ends and U-joints. The same goes for some heavy-duty aftermarket replacement ball joints, tie rod ends and U-joints. But on most late model cars and light trucks, the original equipment steering, suspension and drivetrain joints are all sealed for life and do not require any lubrication or service.</div>
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<b style="font-family: Arial;"><span style="font-size: large;">Fuel Filter </span></b><span style="font-family: Arial;"><span style="font-size: large;">- </span>Replacing the fuel filter every few years or 30,000 to 50,000 miles may be recommended for preventive maintenance, but many motorists have never had a fuel filter replaced! Unless you get dirt or rust in your fuel tank, the fuel filter should last for years or tens of thousands of miles. Many late</span><span style="font-family: Arial;"> </span><span style="font-family: Arial;">model</span><span style="font-family: Arial;"> </span><span style="font-family: Arial;">cars and light trucks no longer even have a recommended fuel filter replacement interval. Instead, they have a "lifetime" fuel filter located inside the fuel tank as part of the fuel pump</span><span style="font-family: Arial;"> </span><span style="font-family: Arial;">assembly. Unless your vehicle is experiencing a fuel delivery problem, therefore, there is no need to replace the filter.</span><br />
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<span style="font-size: large;"><b>Wheel Alignment </b>-</span> Accurate wheel alignment is essential to minimize tire wear and to keep your vehicle traveling straight. If your vehicle has been experiencing unusual tire wear, your wheels may need to be aligned. But if the tires are wearing normally and your car steers straight with no pulling toward either side, there should be no need to have the wheels aligned. Most tire stores recommend a wheel alignment check when you buy new tires. But if your old tires do not show abnormal wear and they lasted at least 60,000 miles, chances are your wheels are still in alignment. Once set, wheel alignment should not change unless steering or suspension parts are worn or damaged.</div>
Anonymoushttp://www.blogger.com/profile/07884952301771193295noreply@blogger.com0tag:blogger.com,1999:blog-2529084104041640172.post-37341938917839636662017-01-06T23:42:00.001-08:002017-01-06T23:43:06.969-08:005 Things Your Vehicle May Need Now<center style="font-family: Arial;">
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<span style="font-size: large;"><b>Coolant Change</b> </span>- Today's long life engine coolants have a service life of five years or 100,000 to 150,000 miles, which ever comes first (not last). Consequently, the coolant is NOT a lifetime coolant that never needs to be checked or changed. After five years, the corrosion inhibiting chemicals in the antifreeze are usually worn out. If the coolant is not replaced with new coolant, corrosion can damage the heater core, radiator and other parts in the cooling system. So keep driving it until something fails and costs you a lot of money to fix, or change the coolant every five years and prolong the life of your cooling system. Use the same type of antifreeze that is in your cooling system now, or refill with a "universal" coolant that can be used in all makes/models of vehicles.</div>
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<b style="font-family: Arial;"><span style="font-size: large;">Transmission Fluid Change</span></b><span style="font-family: "arial";"> - Though your owners manual</span><span style="font-family: "arial";"> may not list a recommended service interval for changing the fluid in your automatic transmission, that doesn't mean the fluid (or your transmission) will last forever. Today's transmission fluids contain </span>long-lived<span style="font-family: "arial";"> synthetic lubricants and are much longer lived than transmission fluid from a couple of decades ago. But heat and hard use can still cause the fluid to oxidize and break down. Because of this, many transmission experts say you can prolong the life of your transmission by changing the fluid every 50,000 miles. Be sure to use the type of ATF specified for your transmission, as there are many different types. Using the wrong type can cause transmission problems.</span><br />
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<b><span style="font-size: large;">Brake Fluid Change </span></b>- Never change your brake fluid? Most motorists never do, until their vehicle needs brake work and hydraulic parts have to be replaced because of internal corrosion. After several years of service, brake fluid becomes contaminated with moisture. This lowers the fluid's boiling point and increases the risk of the fluid boiling and causing the pedal to fade under hard use. The corrosion inhibitors in the fluid also break down over time, which allows moisture and dissolved oxygen to corrode the brake calipers, wheel cylinders, master cylinder, steel brake lines and the ABS hydraulic unit. Changing the fluid every three to five years can prevent this and prolong the life of your brake system. Chemical test strips are available in auto parts stores that can be used to test the condition of your brake fluid.</div>
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<b style="font-family: Arial;"><span style="font-size: large;">A New Battery</span> </b><span style="font-family: "arial";">- Most people never think about replacing their battery until their car won't start. The average life of a lead-acid wet cell car battery is only about three years in hot climates, and four to five years otherwise. Absorbent glass mat (AGM) batteries are somewhat better, and often last a year or two longer than a wet cell battery. Even so, all car batteries eventually reach the end of the road and have to be replaced. So if your battery is more than five years old, better think about replacing it before it dies. That can save you the hassle and expense of a breakdown and a service call.</span><br />
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<b><span style="font-size: large;"> A New Timing Belt</span> </b>- Not to be confused with a serpentine belt that drives the engines accessories (alternator, water pump, power steering & A/C compressor), a timing belt turns the camshaft in many overhead cam engines. The rubber belt, which is actually made of a synthetic rubber such as HSN or EPDM, has a service life of about 60,000 to 100,000 miles, depending on the application. It is NOT a lifetime belt. Eventually it will break. So if your car has a timing belt, look in your owners manual to find the recommended replacement interval. If you do not change the belt, and it breaks, your engine will stop running immediately, and one or more valves may hit the pistons when the camshaft stops turning (if you have an "interference" engine with tight valve clearances). This can cause very expensive engine damage. If your engine has a steel timing chain rather than a rubber timing belt, you don't have to do anything. Most timing chains will usually last the life of your engine (up to 200,000 miles or more).</div>
Anonymoushttp://www.blogger.com/profile/07884952301771193295noreply@blogger.com0tag:blogger.com,1999:blog-2529084104041640172.post-33498989294510942382017-01-06T23:34:00.001-08:002017-01-06T23:34:18.215-08:005 Ways To Save Money On Auto Repairs<center style="font-family: Arial;">
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<span style="font-size: large;"> 1. Take Your Car Back To The Dealer for Free Repairs If It Is Still Under Warranty.</span><br />
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All new vehicles come with a three year or 36,000 mile (which ever comes first from date of manufacture) bumper-to-bumper warranty that covers most almost everything (except "wear" items like brake pads). But some new cars have much longer warranties. Many late model vehicles also have extended powertrain warranties that may go 5 years to 10 years or 100,000 miles, or even lifetime! So check your warranty coverage to see if you may be entitled to free repairs at your dealership.</div>
<b style="font-family: Arial;"></b><span style="font-family: Arial;"></span><br style="font-family: Arial;" /><span style="font-size: large;"> 2. Take Your Car To An Independent Repair Shop When It Is Out Of Warranty.</span><br />
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Many dealers provide great service, but they are also expensive. The average labor rate is typically around $90 to $100 or more per hour, and the price for original equipment replacement parts is usually much higher than comparable aftermarket replacement parts. Independent repair shops can often do the same repairs for less labor and parts expense. But make sure the shop has qualified technicians and that they are using up-to-date scan tool software and other service equipment.</div>
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You can also specify if you want OEM replacement parts or aftermarket parts (new or remanufactured). Remanufactured parts can usually save you, even more money, provided they are from a quality supplier and are backed by a one year or longer warranty.</div>
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<span style="font-size: large;"> 3. Fix It Yourself - If You Can</span><br />
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Many maintenance and auto repair jobs are still simple enough that you can do them yourself. This includes changing spark plugs, filters, belts, hoses, brake pads, sensors and many other parts. Some of these jobs may require special tools, and in every case accurate diagnose of a problem should always be made before any parts are replaced. Guessing at the cause of a problem can get very expensive if you don't really know what the problem is and keep replacing parts hoping this or that will fix the fault.</div>
<b style="font-family: Arial;"></b><span style="font-family: Arial;"></span><br style="font-family: Arial;" /> <span style="font-size: large;">4. Don't Fix It Yourself If You Can't</span><br />
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Trying to repair a problem that is beyond your capabilities can sometimes end up costing you more than taking your car or truck to a dealer or a repair shop and paying them to diagnose and repair it for you. Yes, everybody wants to save money. But if you are not sure what you are doing, or you don't have the proper tools or know-how, you can screw up a lot of things that can be expensive to fix. It will often be cheaper to pay somebody else to fix your car for you.</div>
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<span style="font-size: large;"> 5. Get Rid of Your Car Before It Starts Costing You a Lot of Money</span><br />
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This is the most important tip of all. Though we may dearly love our old car or truck (especially if your car or truck is paid for), it is NOT going to last forever without a lot of repair expense. After so many miles and years, component parts start to wear out, break and fail. The trick to saving money on repairs is to sell or trade your old vehicle before it reaches the point where it is going to break your budget to keep it running.</div>
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Major repairs like a transmission or engine can be budget breakers. The repairs often cost more than the vehicle is worth. Changing your oil, other fluids and filters regularly can help prolong the life of the engine (and maybe the transmission, too). But even highly maintained vehicles eventually reach the point where parts start to fail. The parts most likely to need replacing include the battery, alternator, water pump, fuel pump, brake calipers and rotors, electronic modules (of which there are many on late model vehicles), various sensors (oxygen, throttle position, mass airflow, etc.), catalytic converters, exhaust pipes and mufflers. None of these components by themselves are budget busters, though some parts and modules can easily cost several hundred dollars or more apiece!. It's when you start adding up multiple repairs and repeat repairs that the cost of keeping your old car running starts to make less and less sense.</div>
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So when should you get rid of your wheels? My advice is to sell or trade your old car or truck before the odometer turns 80,000 to 100,000 miles (less if most of your driving is in stop-and-go city traffic, or more if most of your driving is done on the open highway). Or, get rid of it when it reaches its 8th birthday. It might still be running good and may have not cost you a dime yet in repairs, but that isn't going to last. The odds of an expensive repair hitting you sooner rather than later are going up sharply the longer you wait.</div>
Anonymoushttp://www.blogger.com/profile/07884952301771193295noreply@blogger.com1