Idles Rough, Pings, Check Engine Light On -
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post #1 of 4 (permalink) Old 07-23-2009, 05:28 PM Thread Starter
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Hi to all, first post, I have a problem I hope someone can help with. My daughter has a 2002 Galant 2.4L 4 cyl auto. 111,000 miles. all of the sudden the other day, while at a traffic light, it started running rough, the check engine light came on and it started pinging (detonation)very badly on acceleration to the point where it is barely driveable. We have it down to the local mechanic and he is telling us the motor is junk. says cyl1 and 2 have 170lbs of compressiion and 3 and 4 have only 80 and this is the problem. suggests new motor for $2500. The motor idles ok , doesnot skip, doesnot smoke, tailpipe is clean,the pinging under load gets worse as the motor heats up and has been trouble free until now. It acts just like the timing is advanced all the way. I feel it is in the ignition somewhere. any advice or suggestions are welcome
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post #2 of 4 (permalink) Old 07-23-2009, 08:00 PM
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Well i dun kno if id buy the compression theory that yur mechanic is saying. One if the timing has jumped , slightly , as in an old timing belt , faulty hydraulic tensioner, this can cause low compression to a cylinder or 2 and accurate compression on the others. The engine would generally idle fine but on load/ acceleration the off timing would cause timing retard or advance out of specs causing the ignition to be firing too advance or retarded and cause pre detenation spark noise/pinging.

Also , a failing camshaft position sensor can also cause detonation pinging, if its referancing the cam too advance or retarded in actual position to the PCM and causing the ignition firing to be uneven.

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post #3 of 4 (permalink) Old 07-24-2009, 10:55 PM
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I definitely agree with the previous post that it may be broken timing belt. That will almost certainly cause you those problems.

However, try looking at another thing before you blow money away on new engine.... I had a problem with my car at around 100,000 miles. The car started misfiring and running wild, and the CHECK ENGINE light came on. Turns out it was the ignition coil. These will cost you $100 a piece (the engine has 2), and they're real simple to change. Try going to your local Autozone store and have them hook up a computer to your car to tell you the problem with your vehicle. This service is free, and if it's the ignition coil, it will save you $2300.

Hope this helps.
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post #4 of 4 (permalink) Old 07-24-2009, 11:37 PM
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auto repair is kinda the same like a doctor....

get a second opinion...

also ... did they say what codes it had?

did they do compression test and a leakdown test?
there is also a chemical test too tell if exhaust is getting into the coolant that can also help

altho the timing belt probably didnt break a few of the teeth may have come off
if it is the original belt it does need to be checked...

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