Duke Bo-Regaurd

Alright.... First off this is what has been checked and or replaced:

IAC
MAP
MAP plug
TPS
Cap and rotor
Vacuum leak check
Wiring harness traced for breaks
New plugs, champion factory plugs
New NGK O2 sensor
Fuel pressure (45psi)
Regrounding.
PCM spacing.
Injectors tested
Exhaust seems fair
Took off and deep cleaned throttle body.
Alarm not engaged.


This is the issue:

95(obd1) jeep GC lerado. Flash cel code 12, 14, 55.

Code 12 and 55 are nothing, just that the battery has been reset within 50 starts and the all codes read.

Engine will either start and shut off.
Start and idle like trash at 200rpm.
Start and dip in idle (300 to 50 back and forth).
start and run fine for a few minutes with 800-600 idle.
start with a 1200 idle and an incredible sucking sound from the throttle body (like a f*cking jet.)
Start and run fine untill I put it in gear.
Start and run fine untill I move the (new) MAP
Or won't start.

Before you suggest anything please make sure your not randomly guessing. I've seen alot of forums where people just throw out stupid ideas because they don't know about jeeps, and assume that it's an issue that happens to their Honda's.

All of these problems started after I would get a bogging feeling and when I can to a stop the engine be would die randomly. This got worse and worse to where it was happening every time, then I parked it at home and it starts but won't stay running. Since then for the last 2 weeks I've done all the things listed and the problem just keeps changing! I've paid a years insurance and a f*ck ton to get this smogged and tagged(CA) it needs to be fixed and I'm out of money. For the map,tps,and iac. I have three of each. One old two new. Plus the originals.

I can unplug the map and the iac(new or old) while it's in it's "running ok" mode and it makes zero change. Plug it back in, zero change. Then restart it and it will not stay running or it will, it's random. I'll unplug or leave them in. Makes no difference. Sometimes I does make a difference when it wants. Other times it won't.

Plugged cats don't seem likely to cause intermittent issues
PCM is current theory but I can't afford to be wrong.
Wiring harness is possible, as sometimes when I shake the wires while the engines running it will either kill it, or make it run better. But then I can violently rip on it shake it, slap it, spit on it, call it daddy, and it won't make a difference when running good or bad. Only works 1/15 times.

PatHenry

The Grand Cherokee forum (https://www.cherokeeforum.com/f5/) might be more helpful.

Assuming it's a Jeep I6, one thing you could check (and it won't cost you $$, just some time) would be the intake/exhaust bolt torque.

Duke Bo-Regaurd

After three weeks of pain. I've pulled apart the wiring harness and went ham....

The TPS and the MAP share a common wire, it's purple with a white stripe. Took a meter from the main computer plug pin #6 (it's the only only one with a purple white striped wire) with continuity and had connection from TPS to the plug.

I did the same from the MAP to the main plug and got no continuity (this means a brake)

​​​​​​Checked between the MAP and the TPS and still had no connection. Meaning the somewhere between the end of the plug and the spot where the tps meets the map in the wiring harness was broken.

Visually there was no damage. But internally I had a wire brake. Replaced that with and all these weird problems went away.

If your looking this up on Google and you need help

951-210-4757

djgrayxj

Note from DJ
I think this is the diagram of the problem wiring in this post.