Join Date: Feb 2008
Welcome to the forum.
My 97 has had the same issues from time to time. I'm on my 4th PCM. The latest is another Cardone brand PCM....and it's doing it again, once in a while. I bought some dental style picks from Harbor Freight today on my way back from the lake, ( yes, we slaughtered the bass and bream on Toledo Bend this weekend...yay !).... to attempt the most recent "fix", which is to close up the connectors on the harness as described in a thread here. " The REAL fix" is in the title...I believe.
But I dont think that's it, truthfully. 'Going to try it anyway, just to eliminate it as a cause.
I think it's more than that. I think there are other grounding points that become loose. One, as I recall reading about, is under the dash on the firewall near the glove box. ( dont quote me on that one) The A/C unit gets it wet and it rusts the grounding point. We'll see.
I've noticed that when idling, in park, I have a habit of hitting my window buttons, one by one, to make sure the windows are all up....well....the engine RPMs have dropped at times when I do that, which indicates a low current ( amperage) condition in the charging system. This could also indicate a bad ground somewhere....or a window circuit that's pulling too much current w/o tripping fuse or breaker. I'm on my second replacement alternator and my 4th (?) battery since I bought the vehicle new. Are the aftermarket alternators weak or faulty ? What about the cheap batteries we buy now. ( at $100+ today) I have no idea.....but an upgrade is in my plans.
Or is it just the badly soldered boards on many of the PCMs? There are people on here who have had to try 4 different PCMs before they got a good one.
-What about aftermarket O2 sensors? Are they frying the PCMs?
-Clogged cats? Will they cause the ASD relay to trip or screw up the PCM ?
I'm on the second cat now...so we'll see if Meineke honors that warranty this week, because I'm going to see them.
How about low vacuum? I mean....geez...I have 238K on the original engine. Maybe the map sensor and the rest of the BS they put on these engines now cause the PCM to act stupid or lazy, due to low engine vacuum. I have no idea.
I had it fixed for 11 months with a new PCM that was zip tied. Then it ran ok for another 6 months on the replacement. Now the replacement PCM ( Cardone brand, under warranty) is screwing up, mainly on high humidity days, or when the temps drop below 55 degrees at night.
I still have my original PCM and time permitting, I'll get the potting compound out of it with a torch and re-solder the pins, replace any electrolytics in it, and try again. But if there is another unresolved issue somewhere on the Jeep, it may all be for naught until I find it.
I also wonder if oil leaking from the valve cover and/or rear main seal, somehow screws with the crank sensor readings, assuming the oil ever hits the flywheel.
Who knows? I'm still searching for the ultimate "fix", and hitting each of the obvious ones, as time allows. If it was just about money, I'd have it cured already, because money really isnt the main issue in my particular case. I just want it fixed correctly.
2007 5.7 Hemi, Ltd. QD II -
1997 ZJ, 4,0 select trac, Up country, track lok.