Regarding the rough idle and hard starting problem with my 94 JGC 4.0 litre 4X4. I received very helpful information from "81" and Cam7. Yesterday I had a code 34, today it is a code 12. It still idles rough and very irregular and is hard to start after standing for 10 to 20 minutes after driving. It starts instantly when cold. The wires are all secure on the spark plugs and the distributor cap. The rotor is fully down and secure. The cruise control works fine and the engine is as smooth as silk above 1500 rpms and it is getting good gas mileage. I still do not know how to locate and check the EGR valve and I have not checked the CPS. I need more ideas.
Thanks to all. LeLeach

I believe a code 12 stands for battery power to pcm was disconnected,I am having the same problem with my 96',i've changed every senser that the computer tells me to and still i have problems.If you find out any info on the code 12 please let me know. dave92302@netzero.com thank you.

I believe a code 12 stands for battery power to pcm was disconnected,I am having the same problem with my 96',i've changed every senser that the computer tells me to and still i have problems.If you find out any info on the code 12 please let me know. dave92302@netzero.com thank you.


Dave,
My code 12 is correct as I disconnected the battery a couple of days ago. Do you have any idea if the computer can be reset by anyone other than a Jeep dealer? Thanks, LELeach

I dont know but i do not think it is the computer needing to be reset,I think it is more than that.If you can tell me more id be thankfull.Did the dealer tell you it was because of you disconnecting the battery?

try changing the idle air control valve. my jeep idles rough but runs smooth over 1000 rpms. was told it was the iacv. have to go buy one this weekend. they are like $40 at autozone