QuestionI have a 1993 chysler town and country 3.3L 151000 miles. My problem is that it starts to miss fire at about 2200 rpms when it's cold but when it warms up it jumps to 3500 rpms before it starts to miss. If I step on the gas hard it gets really bad. I have changed the O2 sensor,Throttle position sensor,MAP sensor,EGR valve and it has new plugs and wires. It starts good and idles good. It only happens when i hit that certain rpm range. It gets better when its been driven around awhile but still will miss at higher rpms. What do you think might be the problem?
AnswerHi Robert,
Have you tried for fault codes with the ignition key:"on-off-on-off-on and leave on" doing that in 5 seconds or less elapsed time? Then cound the flashes of the check engine light and combine the numbers in pairs to form the two digit fault codes. Then repeat to assure accuracy. 55 should be the last code. We can go from there if you find any specific codes that apply.
If you have and there are no relevant codes, then the shop manual suggests looking at the secondary ignition patterns with a scope, fuel pressure verification, pcm ground and pcm power circuits, egr (which you have replaced), and finally engine mechanical (compression, cam/crank timing verification, exhaust system flow, vacuum gauge reading, injectors). I can xerox and postal mail you the specifics of those "no trouble code procedures" if you would be so kind as to reimburse me for the cost of copying (10 cents per page) plus postage, after you have received the materials.
Roland
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