Cylinder 1 Missfire

jeep
grand-cherokee

#1

Having an issue with the check engine light coming on. The engine code is Cyl 1 Missfire. Replaced the coil pack and check the plugs. Rides well for a short time and again check engine light and the same code. Switched the coil packs and replaced one again. Same thing. 195000 miles. V8.
Anyone experiencing the same? Wondering if it could be the computer.


#2

Did the #1 plug look different?
Is it possible to swap fuel injectors?
After that it’s time for a dry/wet compression test.


#3

Have you tried replacing the plugs and wires? It is my understanding that an out of tolerance plug or high resistance wire can cause premature failure of a coil pack.


#4

Try swapping # 1 plug with another one , see if the problem follows # 1 plug or not . You said you checked the plugs , not replaced . I had a new plug fail with maybe 10 miles on it , replaced it & all’s been fine since .


#5

Don’t think that is the issue. The fuel injector has no bearing on the issue.


#6

Well…thinking that would be next course of action. even though the plug looks good it could be the source. Thanks for your reply.


#7

Thanks but there are no wires.


#8

Missfire can be caused by a bad injector.


#9

I believe you may be using faulty logic

Us mechanics on this website have undoubtedly all experienced misfires which in fact WERE caused by the fuel injectors

I have, several times, in fact

A misfire is a misfire, regardless if it’s caused by a fouled plug, bad wire, bad injector, low compression, etc.

The pcm is probably not the issue here. Only after all diagnosis has been performed, and everything else has been ruled out, should you consider the pcm. That’s my opinion, FWIW