jeep stalls at idle?

2000 jeep Cherokee, bone stock, 4.0, selec trac 4x4.
it started happening this winter, I will come up to a stop while in drive and the idle is rough, and will stall sometimes, not all the time, so I'm wondering if there is like a idle positioning sensor? and if so where is it, and if not, what else might it be.
thanks

JACKO78

Clean the Idle Air Controller.


Cleaning the Idle Air Controller (IAC) :

Purchase sensor safe Throttle Body cleaner spray.

1. Remove the Throttle body from the intake manifold.
2. Remove the IAC with a TORX 15 driver (2 bolts)
3. Gently wiggle out the IAC from the throttle body
4. Clean the IAC with Throttle Body Cleaner (not carburetor cleaner). Use cleaner, a rag, and a toothbrush. Be gentle; don’t twist or pull on the pintle as it is fragile and can be damaged easily
5. Also clean where the IAC seats in the throttle body with the same throttle body cleaner
6. While you have the Throttle Body off, give it a good cleaning also.
7. Reinstall IAC, the Throttle body, and check idle quality.

.

thanks!


JACKO78

Having a similiar problem with 2000 jeep cherokee. Replaced the air idle control motor, throttle position sensor, crankshaft position sensor, checked for vaccuum leaks, new coil pack and plugs, had to replace the ccv orifice and grommet due to pinhole, ran a new ground to the battery because old one was SO corroded. Still a really low idle and stalls at stops and acceleration from stop. I love my Jeep and am not sure what else I can do or where to go from here. I have some temp sensors needing to be replaced and an o2 sensor code also but everyone says these would not cause these problems any ideas and to who started this thread have you found anything out.

cole2011 said:

...... I have some temp sensors needing to be replaced and an o2 sensor code also but everyone says these would not cause these problems ......

Click to expand...

Fix the known problems, see if the other issues clear up,


...........or don't. Proceed with your diagnostic troubleshooting from there.

Did you find the issue? My 2001 XJ is doing the same thing. I replaced the TPS, cleaned the IAC, replaced some vacuum lines, and can not figure it out.

Three times now I had the same issues. I cleaned the IAC and it seemed to help some for awhile, the first few times it happened. The first few times it was just a sticky IAC, mostly on a cold motor. Another time it was my alternator failing and the third time it was a battery on the verge of a catastrophic failure.

Cause and effect, I replaced the alternator and my (periodic/sporadic) IAC problems disappeared. A year latter I replaced my battery and my IAC problems disappeared. There was definitely a connection between my lazy IAC and my charging system. I just don't know exactly what it was. Best guess is the IAC needs all the available voltage it can muster to work well and some sort of charging issue, that may be hardly noticeable on the volt meter or the way the starter turns over, may affect IAC function. The only noticeable indicator I had was my headlights seemed not as bright as they used to be.

With the IAC, if I gave it a little pedal the motor would run fine, my IAC tended to stick closed, which constipated the airflow at idle. When my CPS was failing, I had to coax some RPM's out of the motor by feathering the pedal. The IAC and CPS would act much the same (sometimes) when I was coming to a stop, at low RPM's the motor would stall (IAC) and/or miss (CPS) and the idle would fall.

Just a possibility.

I also had a MAP fail, the motor ran really rich and would idle very low (if at all). Clouds of soot came out of the exhaust.

Figuring out if it mostly happens on a cold motor or a hot motor may help with diagnostics. My IAC seemed to be worse on a cold motor, low battery after a few short stop and go trips before the battery had a chance to recharge. When my CPS failed it seemed to be worse right at the transition (140-160F) from a cold motor to operating temperature. It my have been something specific to my XJ, I also had a lazy O2 senor at the time.

Just some ideas.

Not saying this is your problem but don't ignore the possibility of a marginal battery. It is among the top 2 causes of stalling at idle. You can have a battery strong enough to start the engine with no issue, but marginal enough to create fits with the engine management system.

Any parts store will "load test" the battery for free. Load testing is the only conclusive way of determining battery condition.

And I agree with the others on cleaning the idle air control and throttle body. Bench cleaning is best.

Good luck and keep us updated!