Went thru the same exact thing. ECM

 

I've owned my XJ for about 8 months now. It has randomly stalled out on me twice. I just had it in the shop thinking they would find the fuel pump is going out. But unfortunately they could find absolutely nothing wrong.......

 

Did anybody get there truck to work correctly?

I have a 96 Grand Cherokee with 4.0L, autotran, 4wd and AC. I've replaced most of the things that other folks have mentioned including two dealer installed PCMs (paid for the first one not the second).

I started trying to find out on my own what was wrong since the service manger at my dealership told me they were going to have to play it by ear since no codes would show up (read throw parts at it).

I've been working on my own vehicles for a long time however this is the frist one with full blown PCM.

My truck just quits running it doesn't matter where or at what rpm. Sometimes when it's going at highway speeds it will just die for a couple of seconds. Most of the time if I wait about 30 seconds after it quits it will start right up.

I sure would like some help with this one. Oh and the battery (went through the bad battery thing a couple of years ago) and altenator are new also.

Thanks in advance.

Doc

 

Sounds exactly like what happens when the Crankshaft Position Sensor starts to go bad. Have you replaced that? I had the exact same problem on mine - it would die at any speed, highway or not. It's a very common issue on the 4.0L engines. It's also possible, if you have replaced it, that the position is off by a little bit, or that you got a replacement that suffers from thermal failure (also common). The other less likely thing it could be is the Camshaft Position sensor (it works together with the CKPS and PCM). Both are relatively easy and simple to replace.

Does the tach drop to zero when the truck shuts off? If it instantly drops to zero it's almost certainly the CKPS.

 

The Root Cause to my issue was a loose distributor. There's one bolt that secures it to the block. Mine was loose. I tighted it up, and the issue went away.

Check the Ignition Switch, the 96 vintage is notorious for them to fail. Sounds like the exact same condition I resolved a few years back.

As for the Crank Position and Cam Postion sensors, those are only use during engine start-up. The service manual will step you through how to test those out.

 

That's absolutely false

 

Thanks for the new ideas.
I've replaced the:
Crank position sensor
Cam shaft postion senor
Plugs, cap, and wires
Coil
MAP
IAC
Coolant Temp Sensor
PCM (twice done by dealer)
Altenator and Battery (because dealer said they were bad)

I think that's it, just about everytime I replace something it gets better for a couple of days then starts acting up again.

I thought about the ignition switch but when I've had those go bad in the past (not on Jeeps) it would take the whole system out not just stop the engine from running. How did you trouble shoot the switch?

Thanks for the help I really want to get this back to being the reliable truck it used to be. I've had it since 1999 and never had anything like this happen before.

Doc

 

my jeep has bee running great since i replaced the iac .... it stalled on me one time but i think thats because i got it flooded when i tried to start it

so far soo good for me

 

Hey blackxj,

I'm glad someone got this under control.

73's

Doc

 

Trouble Shooting the Ignition Switch: Well it was an intermittent thing, very hard to diagnose as it seemed to magically fix itself. I started to look on the forums and all hinted to the ignition switch as the engine would not crank in the faulted mode. The rest of the vehicle did still have power (Radio, HVAC, etc..). The issue started to occur more frequently until one day it just wouldn't crank. I thought it was the "Park/Neutral" switch, but after I replaced that, it still wouldn't crank. I took the ignition switch out, and it was clear that the trace was burned out.

I fixed that about 2 or 3 years ago, and haven't had that issue again.

 

Hey Drew,

So when your ignition switch was failing the truck wouldn't even crank? If that's the case then its not my problem mine will crank just fine but it won't catch.

Doc

 

I replaced my crank sensor, and also wiped off the ground wires connected to the oil dipstick bracket because they were coated with oil. Haven't had a problem since, but it hasn't quite been long enough to completely confirm my problem is fixed. You can read more elaborate details of my random stall issue in my thread titled "cps or electrical".

 

Define bad.

 

yes i know jeeps dont get good gas mileage whatsoever

but i was getting around 8mpg city and around 9-10mpg highway shouldnt be that bad for all stock on 31x10.50

now idk i get maybe like 14-16city and 16-18 highway