1990cherokee4x4

I've never heard of an o2 sensor problem connected to any PCM problem before so I'd say is probably just old but I'd wait till you have the PCM changed before getting the new one
As for the coil I dont think it could be affected by a motor dieing or shutting down -
At first I thought my problem was all ignition and I got a code for it too and I changed my distributor and coil but it made no difference after the first week
So I'd have to say don't get a new one till the PCM gets changed

OnAll4s

So 5 days since new PCM install. Cleared codes right after and no problems what-so-ever.... Jeep runs like tank. Very happy with the outcome. Final total is;
$1500 for jeep
$2600 for rebuild and install.
$720 for PCM
Total $4820 for a GC that will run another 200k+ and years to come...
JEEP=
Just Empty Every Pocket... Lovin it!!!

OnAll4s

Sorry, just reading this thread again and saw this. I had the original 4.0L stripped down. Bored and rebuilt. Almost done with the first 500 miles...

XxRoll4LifexX

720 bucks for pcm??? was this just the part or was that including labor?
i have never thought of myself as a mechanic and well till the day i had to replace a starter in my 91 nissan sentra. i never even cared about cars or trucks then i rebuilt the front end on my 91 jeep Cherokee after rear ending a little honda but honestly i thought that part was 200 bucks and from the looks of it super easy to install... so how did it cost you so much?

jknob1986

I paid 225 to have one rebilt and programed to my vin and millage. And it was not even the problem.

jknob1986

OnAll4s

$577 from dealer. I researched for 6 days on companies that offer rebuilt PCMs and this is what I learned. Of 5 such companies, ALL FIVE had a rating of "F" with the Better Business Bureau. Most with 100+ complaints in the last 12 months with the BBB finding over half of those " company refused to comment on transaction" an the rest were " company did not honor it's commitments( warranties)....
Bottom line... Yea you could buy one for 200$ but it's a roll of the dice. You may get a good one or you may not, and if you don't then you might as well have just lit that $200 on fire. I just dropped a ton of money rebuilding my engine( best engine ever made IMO). so I was not about to roll the dice. PCM was $577 plus tax and 1 hour of labor to have them flash it and install it.

As far as the PCM not fixing your problem. I know electronics well enough to narrow down and eliminate possibilities. The rest of what I learned I obtained from asking questions in here. You can learn a lot from other peoples dealings with the same or similar issues. Hope this helps...

jknob1986

Jeep!!! Jeep!!!!!!!¡¡¡¡¡

1990cherokee4x4

Well after many weeks off no problems the jeep died 4 times wile driving and felt really down on power and back fired a few times
- had to limp it hope
Ive gone over every connection every fuse and relay I can find and none are bad
I'm pump out of ideas of what it can be besides the PCM

OnAll4s

What's mileage like on your jeep? 4.0?
That's the same thing mine was doing before I tore it apart... Idk if the PCM was the cause of it or not, but cylinder #3 collapsed on itself. I barely got home... Be very careful. PCM could have caused an ill-timed spark and messed it up or just went from age. I'm not that smart in engines. But mine would finally turn over, and I had to put it in N when slowing to keep RPMs up so it wouldn't die out.

I don't know your exact issues but I lucked out. When piston collapsed it fell into oilpan. Machinist at NAPA said usually it will lodge against the block wall an gouge the wall. Which means the block is shot at that point... Might be more money but I wouldn't look past PCM and engine replacement... It may end up being one of the two... Keep us posted

1990cherokee4x4

Its got 246090 as of this morning
4.0 HO motor 1997

I don't think any of the pistons are failing yet because of how quite it runs ,I've heard pistons let go and get jammed in the cylinder walls before and it's not a pleasant sound

I would most likely sell it if I had to re build it cuz I just don't have time
How sad is it that a mechanic does have time for a motor

I may try to get a new PCM if all else fails

OnAll4s

Could also be one of connectors. Mine had a problem. Went to junkyard and cut one off and soldered it on. Took about 2 hours including junkyard and about $7. Play with all the wires going into PCM and see if engine cuts out or picks up when moving a wire

1990cherokee4x4

Just giggled the wires on the PCM and as soon as I touched the middle set it sputters so I did it a again and sure a hell it died so I'm pulling out the coolant bottle right now to see what I can do

XxRoll4LifexX

this looks nasty, can this acure from the engine dieing? .. i drove the jeep all the way to skibowl here in oregon.. made it there and back with out it dieing... would hate to drive it again there and have something like this happen. how much does the dealership charge to check out a vehicle? guess i will contact one tomorrow and see

DeepSouthXJ

Ahh, now we're getting somewhere. You might try some good electronic cleaner on your connector pins. I use products from MG Chemicals on stereo equipment. Be careful to get one that is safe with plastics. Mine sputters sometimes also. I need to check the connector now. Hope you get it worked out.

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