96 XJ stumbles then shuts off when warmed up. P0171

[Anak]

Originally Posted by Mrpd1501

Bigger, and more plentiful. It's copperhead, rattler, and alligator baby season down here. Watching your step is a key method in keeping your leg.

Egads!

I am okay with rattlers. Grew up with them all over the place. They at least give you a courtesy warning before they try to kill you.

Copperheads, those worry me. Very well camoflaged and no courtesy warning. No thanks. I will stick with my rattlesnakes.

[Rob Mayercik]

[QUOTE=Anak;
Copperheads, those worry me. Very well camoflaged and no courtesy warning. No thanks. I will stick with my rattlesnakes.[/QUOTE]

We have those here in my neck of NJ too. Back in the 70s after my folks bought their house, the old lady next door told them that copperheads give off a cucumber smell (not sure if all the time, or only when shedding their skins).

Thankfully, neither my folks, my sister, nor I have ever have had occasion to put that little tidbit a practical test...

[CJR]

I had similar problems with one of my XJs. It was defective relays. Replaced the relays and my problems were solved. Relays are typically electro-mechanical devices and the contacts corrode and open the contacts/open circuits. Your fuel pump relay maybe opening and shutting off the fuel pump.

Best regards,

CJR

[4x4Phil]

Had this exact issue on my 96. Cps sensor replaced and good to go. I bought a spare to keep in the truck.

Sent from my Pixel 6 Pro using Tapatalk

[Mrpd1501]

Sooooooooo
I’ve literally replaced everything.
Warms up fine. Once I get to op temp, stumbles and shuts down.

If I disconnect the battery for a minute, then put it back on, it fires right up.

[Unclewolverine]

X2 on cps, just had similar issues with mine randomly shutting down when hot. 5 minute cool down and it would fire right back up. New cps solved it.

[Mrpd1501]

Originally Posted by Unclewolverine

X2 on cps, just had similar issues with mine randomly shutting down when hot. 5 minute cool down and it would fire right back up. New cps solved it.

I thought the exact same thing because the symptoms are so similar. Unfortunately, even after replacing the cps, the issue persists. No codes, just stumble then shut down at operating temperature.

I replaced the pcm when i bought it (reman from FS1), due to some blown injector drivers. Going to put the old one back in since I've repaired it, and test to see if the one I've been using has some kind of fault.

Need to find a detailed explanation of what changes when the engine reaches operating temperature. There has to be some simple thing I'm missing.

[Unclewolverine]

Does a 96 have the two temp senders or the integrated single unit?

[Mrpd1501]

Originally Posted by Unclewolverine

Does a 96 have the two temp senders or the integrated single unit?

You know, I wouldn't even know how to answer that. Talking about coolant temp senders? I can go look as soon as this weather passes.

[Anak]

My '96 has one temp sender in the T-stat housing and a second one at the back of the head.

[Unclewolverine]

The one at the front is the sender for the computer, might try unplugging that one and seeing if the problem persists. The one at the back of the head. (If applicable, ) is the sender for the gauge.

[Mrpd1501]

Originally Posted by Unclewolverine

The one at the front is the sender for the computer, might try unplugging that one and seeing if the problem persists. The one at the back of the head. (If applicable, ) is the sender for the gauge.

Well, the gauge doesn't work, so maybe there's a dependency there? I'll go look for the one at the back of the head shortly.

[Unclewolverine]

If you have the rear sender it's my understanding that it only serves the gauge so it should have no effect on operating parameters. But if you unplug the front sender, the computer *should* default to warm up mode and stay there. That should tell you if its something in the computer that switches over once it hits operating temp.

[Mrpd1501]

Originally Posted by Unclewolverine

If you have the rear sender it's my understanding that it only serves the gauge so it should have no effect on operating parameters. But if you unplug the front sender, the computer *should* default to warm up mode and stay there. That should tell you if its something in the computer that switches over once it hits operating temp.

so if i fire it up cold and just unplug that sender on the thermostat housing, it should replicate the behavior? Am i reading that wrong? It'd be real cool if that's an easy way to test.

[Numbers]

When i bought my 96, I had issues with it bogging down and dying when hot. It wouldn't re-start until it cooled off a bit. CPS turned out to be fine, but the bolts holding it in were finger tight at best. I guess when everything was hot and heat soaked, the sensor would move to a less than ideal position.

Confirmed on the two temp sensors. The rear one goes to the gauge and i do not believe it has anything to do with engine management.