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Jim Grant's Tech Tips
‘96 Chrysler Sebring, Shaking, Rolling & Not Going
Q: I’m having major problems with my '96 Chrysler Sebring. About 6 weeks ago it started running really rough, rough idle and some shaking. It would hesitate during driving, lag, every now and then. I took it to a mechanic and they said it needed a complete tune-up, which would run me about $800. I didn't get the full tune up but had my mechanic friend replace the spark plugs and wire set; I also ran a fuel injection cleaner through the tank. It seemed OK for about a week but then started running rough again. This week it started running really poorly, it won't turn on right away and I usually have to give it gas to get it to turn over, plus now it is dying whenever I come to a stop (stoplights and when pulling in to park). The check engine light came on as well, and it is coming back with a P0300 Random/multiple misfire code. I don't know what to think, and I don't want to have to pay my mechanic another $75 diagnostic fee just for them to tell me it needs a tune-up. Any suggestions as to the problem? I have an extended warranty and would like to get this problem fixed under the warranty.
- Stefanie
A:
One of the things you should know about extended warranties is that most of them do not cover the cost of diagnosis. It is very unlikely that they would ever except, “it needs a tune-up”, based on a computer code. They want to see the diagnosis and the explanation for the needed repairs. In addition, these companies will want to know, with a written estimate, just what repairs are needed, their cost and relationship to the complaint. They expect the owner of the vehicle to cover these expenses. Give them a call and ask. I’m pretty confident you’ll find I’m right on this one. If not, I owe you a coffee and you got one heck of a good extended warranty. If I’m right and you don’t want to spend the money for diagnosis then you’re going to find out just how good of a friend your mechanic friend is. For some reason I think your vehicle has a vacuum leak and the vacuum leak is large enough that it is causing the engine to misfire. Of course the argument would be that there should be a different code. True in some cases and not in others. A broken vacuum hose, bad intake gasket and items on that line introduce additional oxygen (outside air) to the engine. The computer would report this as a lean running condition. If the condition became severe enough the engine would skip or misfire. Misfire codes are priority codes, which means they will bump out other codes and move to the front of the line. Now it gets even more fun. There is an emission control that, when stuck open, will cause a vacuum leak. What is unique about this emission control is that it does not introduce addition oxygen. It allows exhaust gases to enter the engine. Because there is little to no oxygen in the exhaust gas the computer won’t report a lean running condition. It might even report a rich running condition due to this failed emission control. Also, if this valve is stuck or sticking open it can cause the computer to set a random misfire code. Have your mechanic friend check your car engine for vacuum leaks and then check the EGR valve very closely. If I’m right, I’ll take a double espresso.
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