QuestionQUESTION: I have a 99 Chrysler T&C Limited 3.8L front wheel drive and recently it started chugging and sometimes misfiring. It only seems to happen when it warms up, never when I first start it up. Last year it seemed to do the same thing and we were told it was the coil pack and had that replace. A year has passed and it is doing it again. The mechanic who replaced the coil pack didn`t think it was the coil pack again. He plugged it in for the codes and it read misfire on cylinder #3. It seems to come and go and sometimes is really bad and other days it just chugs. My RPM`s don`t seem to fluctuate when it happens either. Any thoughts?
ANSWER: Hi Maria,
Just to be sure we have all the possible fault codes:
The best way to find out is to use the self-diagnostic capability on board using the ignition key:"on-off-on-off-on and leave on" doing that in 5 seconds or less elapsed time. Then watch the odometer window of the cluster to see the mileage reading change to show a 4-digit number preceded by a P. Let me know the number(s) and we'll go from there.
It may be there is another code than the 0303 that your mechanic noticed.
Roland
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QUESTION: I tried the on/off sequence and it showed nothing other than the mileage. I wasn't sure if you truly need to start the car but I tried it both ways.What am I doing wrong?
ANSWER: Hi Maria,
It may be that in '99 that code readout wasn't available. I assume that you did the switching fast enough as to complete the process in 5 seconds or less. And by 'on' I meant only to the run position of the switch, not to the start position so that is correct.
It may be the case, though I doubt it, that instead of the 4-difit numbers showing up in the odometer, that instead the check engine light, which remains 'on' when you leave the key in the run postion after the key 'dance', that light will begin to flash, pause, flash, etc. If so, count the number of flashes before each pause, then let me know the flash counts in order of appearance. Repeat the counts for accuracy is that is what happens.
If the misfire on #3 is the only current code, then it would be good to check that you have good apark on the #3 plug, that the compression on the #3 cylinder is good (at least 100 psi), and finally that the fuel injector is functioning properly. Those are the major causes of a single cylinder misfire. The observation that it appears to happen only when warmed up has a variety of possible reasons, but the fault code readout would be the only efficient way to find out which.
You can as the mechanic to read the codes again, or go to an Autozone parts store where they often will do a free code readout.
Roland
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QUESTION: So I tried it again by turning the ignition on/off sequence within 5 seconds and it showed nothing again. The check engine light didn't stay on either. I'm not sure if this has anything to do with it but when I went to pump gas the other day I noticed that there wasn't a vacuum when I opened the gas cap. We live at 8000 feet and as I drive around town here our altitude fluctuates so we build up pressure in everything when we go up and down. I have noticed in the past when I open the cap that is is like opening a can. If the seal is bad could this be my problem? Maria
AnswerHi Maria,
It is surprising that the check engine light doesn't remain 'on'. If you simply turn the key to 'run' and don't start the engine then the check engine light should stay 'on'. Try that and let me know.
But in any case, I would either have the mechanic read the codes or get a free code readout via a plug-in code reader. Get the actual numbers of the fault codes. I really can't suggest what is wrong without some such fault code.
Roland
