1996 Jeep Cherokee Cold Start Stall

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BERN3006
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  • 1 POST
Hello everyone,
I have a 1996 Jeep Cherokee with a 4.0L engine. It has 205,000 miles on it. I recently had to replace my altenator. While losening the tension bolt for the serpentine belt I broke what looked to be a temperature sensor on the engine block. After I got the car back together the car would not start unless I constantly gave it gase. I went to the dealership and bought a new one and installed it. It seem to fix the problem. However, when I went out the next morning to start the car it would turn over but would not start until I actually gave it gas. The moment I take my foot off the gas the car dies. However, if I put the car and gear and am able to get the car into 3rd gear (it's an automatic, so I have to actually drive on the road with two feet) it runs perfectly fine and does not stall. It only happens on cold startup after the car has been sitting for an extended period of time. I have a feeling it is a computer problem but I am not sure. Any thoughts would be greatly appreciated. Thanks so much for your help!
Nov 11, 2006 at 3:12 AM
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BOB WILSON
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  • 13 POSTS
YOU CAN CK THE FUEL PRESSURE ON YOUR VEHICLE BY REMOVING A PLASTIC CAP THAT COVERS A NIPPLE ON THE FUEL FEED LINE TO THE INJECTORS. IT IS SIMMILAR TO A TIRE STEM WITH A NEEDLE VALVE. PRESS THE NEEDLE VALVE DOWN SLIGHTLY TO EXPELL FUEL PRESSURE AND CONFIRM YOU ARE GETTING A GOOD FUEL SUPPLY. DO THIS WITH THE CAR NOT RUNNING AND THE IGNITION KEY TURNED OFF, AS THIS IS AN ELECTRIC FUEL PUMP. PLACE A RAG UNDER VALVE TO COLLECT SPILLAGE. IF WEAK PRESSURE, ITS ACLOGGED FILTER OR BAD PUMP. IF STRONG PRESSURE, I'M NOT SURE.
Dec 5, 2006 at 11:09 AM
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CARUNDELL
  • ✓Experienced Mechanic
  • 602 POSTS
[quote:c2aaac7c09="bern3006"]Hello everyone,
I have a 1996 Jeep Cherokee with a 4.0L engine. It has 205,000 miles on it. I recently had to replace my altenator. While losening the tension bolt for the serpentine belt I broke what looked to be a temperature sensor on the engine block. After I got the car back together the car would not start unless I constantly gave it gase. I went to the dealership and bought a new one and installed it. It seem to fix the problem. However, when I went out the next morning to start the car it would turn over but would not start until I actually gave it gas. The moment I take my foot off the gas the car dies. However, if I put the car and gear and am able to get the car into 3rd gear (it's an automatic, so I have to actually drive on the road with two feet) it runs perfectly fine and does not stall. It only happens on cold startup after the car has been sitting for an extended period of time. I have a feeling it is a computer problem but I am not sure. Any thoughts would be greatly appreciated. Thanks so much for your help![/quote:c2aaac7c09]

Hey bern!,
Try this little trick, cause it sounds like you replaced the coolant temp sensor and in the process the PCM may have "learned" and compensated for the issue ..... So....we're going to do a Dynamic Reset of the PCM ....disconnect both positive and negative battery cable ........ rub the ends of the pos and neg ends together for about 5 -10 seconds (not on the batt!!! just the ends of the cables together) then reconnect the battery normally. Then turn on the ignition, but don't start it, for 10-20- seconds, turn off the ignition and then try to start it normally. Don't be surprised if you have to "feather the gas" for a little to get it to idle, cause in the process the IAC control is also "learning" too. It may also start normally too .... it depends

Regards,

Chris
Dec 5, 2006 at 11:37 AM

Suggested Repair

After the coolant temperature sensor replacement, perform a PCM dynamic reset: disconnect both battery cables, briefly touch the cable ends together (not on the battery), reconnect them, turn the ignition on for 10-20 seconds without starting, then start and let the idle air control relearn, feathering the throttle if needed. Also check fuel pressure at the injector feed-line test port with the key off; weak pressure points to a clogged filter or failing pump.

Conversation Summary

A 1996 Jeep Cherokee 4.0L stalls on cold start after a temperature sensor was broken during alternator work and then replaced. It cranks but dies unless the throttle is held, yet runs normally once driven and warmed. One reply suggests checking fuel pressure at the rail test port. An expert says the PCM may have adapted to the bad sensor and recommends a battery-cable PCM reset so the idle control can relearn.

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