Weird stalling issue with 99 XJ

Blaze

Blaze

The Jeeper Reaper
Joined
Aug 9, 2005
Location
Wake Forest, NC
So my son's XJ has been doing this weird stalling thing in the mornings. 99 XJ, 4x4 4.0L auto. It starts fine and idles ok, but when you give it gas it seems to want to stall and then eventually it does stall, mostly when you get to the first stop sign in the neighborhood. You give it some gas and it fires right up and it is fine the rest of the time.

Replaced the IAC and TPS, no change. No codes, nothing. I'm stumped, I've owned over 100 of these things and I've never had this happen before.
 
Moar throddul!
 
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Blaze said:
So my son's XJ has been doing this weird stalling thing in the mornings. 99 XJ, 4x4 4.0L auto. It starts fine and idles ok, but when you give it gas it seems to want to stall and then eventually it does stall, mostly when you get to the first stop sign in the neighborhood. You give it some gas and it fires right up and it is fine the rest of the time.

Replaced the IAC and TPS, no change. No codes, nothing. I'm stumped, I've owned over 100 of these things and I've never had this happen before.
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Did you replace them with mopar or parts store ones?
 
upstream 02 as mentioned. The NTK are what these engines like.
 
If the 1/1 O2 doesn't help (it likely will), try unplugging the clock spring and take it for a drive. It shares a 5v reference with the TP, IAC and other sensors. When it becomes corrupted, it can cause voltage issues that cause exact symptoms of a failed _____________ (whatever is 5v referenced).
 
Jody Treadway said:
If the 1/1 O2 doesn't help (it likely will), try unplugging the clock spring and take it for a drive. It shares a 5v reference with the TP, IAC and other sensors. When it becomes corrupted, it can cause voltage issues that cause exact symptoms of a failed _____________ (whatever is 5v referenced).
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Interesting. Honestly, that might be the culprit. The horn sometimes decides not to work, so who knows.
 
So update on this thing. We replaced the clockspring but didn't help. He found a way to deal with the stalling when it was cold but recently it started doing it more and more. This morning he called me and said he was pulling in to the school parking lot and the CEL came on and it stalled. He started it back up, still CEL and stalled again. He managed to get it running long enough to get it to his parking spot. I ran out there and on a hunch I brought the new battery I just put in the shop truck. It had two TPS codes, cleared and restarted, still there. Jeep running like crap and throwing the code. I swapped out the battery and it fired right up, ran fine. I drove it around, no stalling. He left school, went to gym, then home, then to grocery store and back home. No stalling. The old battery checks out voltage wise, which is super weird. Maybe something goofy internally. Alternator checks out also. Hopefully it resolved itself but still bizarre.
 
Is it an agm battery? There is a different tester for those as opposed to the conventional lead acid testers. Dude at Napa used it to diag a bad battery in the wife’s Cummins a few months back after o’ retards said all is well. She was having weird electronic issues and occasional weird shift patterns when cold. New batteries and all is right with the world.
 
skyhighZJ said:
Is it an agm battery? There is a different tester for those as opposed to the conventional lead acid testers. Dude at Napa used it to diag a bad battery in the wife’s Cummins a few months back after o’ retards said all is well. She was having weird electronic issues and occasional weird shift patterns when cold. New batteries and all is right with the world.
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No, just good ol' lead acid junk. He said it isn't stalling any more but doesn't think it is totally right. I'm starting to wonder if ECM is dying.
 
Blaze said:
No, just good ol' lead acid junk. He said it isn't stalling any more but doesn't think it is totally right. I'm starting to wonder if ECM is dying.
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check the connector on the back of the alt. that excites it. The alt. is controlled by the ecm through this connector. if battery voltage is low it wont charge correctly.
 
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