I'm at a complete loss here. I have an 87 Cherokee Wagoneer 4.0L auto 180k that starts and runs until you park and turn it off. Once you start it again (2 out of 3 times), the idle jumps to around 2500k, once i shut it off it wont start again until cool and then the cycle starts all over again. The engine will crank and there will be spark and fuel pressure but it wont fire.

During the faulted condition Ive tested/replaced:
MAF
vacuum connections
Crank position sensor (replaced)
camshaft position sensor(replaced)
fuel pump
coil
plugs
plug wires
battery
and replaced numerous connections/wiring

Here tomorrow ill be testing/replacing:
Injectors
more wiring
02 sensor(probably replace because its old)
coolant sensor
cylinder compression
IAC (if i can get an actuator)

Have any of you encountered a problem like this? Ive done some serious research on similar issues so I'm putting my money on higher resistance once the engine reaches temperature but I don't really know where to start so Ive just been replacing obviously damaged connections or cables. . I'm just curious if there is something blatantly obvious that I'm missing?

 

Put the parts cannon away for a while and go to my website.
Tips 1 through 5 need to be thoroughly done.
www.cruiser54.com.

 

Will do, thank you!

 

You have to promise you'll report back though.

Think about doing #27......

 

So, I ran through steps 1-5 with no change. I replaced the dipstick grounding connections as they were corroded/loose as well as a few other connections that needed some Tlc. After that I moved around some relays to make sure they weren't sticking but no change. I don't have a tool to test the IAC, though I'm.not sure it's that because I have no problems that reflect symptoms of it failing while driving. I looked into #27 but I think I'll wait so that I'm not doing rework if i end up replacing the wiring harness.
Any other suggestions?

 

What ohms reading did you get in Tip 5?

You won't find an IAC actuator.

Perhaps testing the TPS per tip 8?

 

Step 5 gave me around .4 to .5 when I wiggled the wiring when it was warm. Also, the TPS measured correctly.

 

I wager you have an issue with the intake manifold gasket... or a crack in the gasket. I'd want to do a re-torque of the bolts and a look for any visible cracks.

 

Okay I'll look into that, would that cause it to run weird? It ran fine once it started. Now I can't get it to start lol.

 

Since it won't start, what are you missing and where?

Spark at the plugs or no?

 

Spark and fuel are there. It started running really rich earlier today and now it won't start and after it cooled down it would sputter and backfire but thats it. The O2 sensor tested bad so that's not helping either. I also think that replacing the IAC wouldn't hurt since the idle was all over the place before and it looked pretty worn when i cleaned it. Im just curious if theres another way to test it without the tool mentioned to do so, I'd hate to throw away $60.

 

How is the hose/tube to the MAP sensor?

O2 sensor won't make it run that rich if it's bad anyway.

 

Hose to the MAP is good, as is the sensor.

 

Mixture is influenced by these 3 in order:
MAP, CTS, IAT.

 

Sounds like iac. swap em in from a junkyard. IS The distributor shaft worn so bad the rotor is coming out the side of the cap? did you use mopar cps and ckps or not?