97 TJ 4.0 runs rough after PCM replacement

Pat Goode

Member
Joined
Sep 19, 2018
Messages
64
Location
Uk
I got this second hand PCM to replace the original one on a UK export model. UK TJ,s are fitted with an aftermarket immobiliser that is no longer supportable.

Unfortunately when fitted the TJ runs very rough and throws up engine warnings. I’m wondering if I’ve got one of a 2.5 4 cyl by mistake. Does anybody recognise the part numbers please.

92486
 
I don't know anything about the part numbers, but I can tell you for 100% certain that a 2.5 4 cylinder PCM wouldn't work with your 4.0. Even if you got it to plug in (I don't think you could, as the harness is different), it wouldn't even start up.

Something else is going on, and it's likely not related to the PCM.

Have you scanned it for error codes?
It will plug in perfectly and that part number is for the 97 2.5L 4 cylinder engine.
 
Ah! that explaines it. I need to source a PCM from a 6 cyl.
It runs great on the original PCM, however starting is getting to be a problem as the export imobalizer is starting to play up. (May & Scofield)
 
It will plug in perfectly and that part number is for the 97 2.5L 4 cylinder engine.

No shit? I’m astonished. I didn’t even think it would fire up with the PCM from a 4 cylinder.

Guess I learned something new!
 
Won’t start at all now. Totally dead.
Has anyone got a similar TJ who could send me the part numbers off the PCM, mine have come off.
Mine has a distributor
 
Sorry yes . Export model (UK) RHD
However all export model to the UK had a May & Scofield immobiliser fitted by Jeep, once imported. It’s this unit that has failed, so the only solution is to source a USA spec PCM from a 1997 model year. ( before SKIS)
 
Hey Pat, what kind of ECU did you buy exactly? I ordered one from the USA and they programmed it for me but the immobalizer is still not being bypassed? Thank you. Hope you see this. Daniel