The Jeep Cherokee (XJ) is a compact SUV that was manufactured and marketed by Jeep from 1997 to 2001. Sharing the name of the original full-size SJ model, but without a traditional body-on-frame chassis, the XJ instead featured a light-weight unibody design.

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Idle problem remains a odd frustrating headache after much work.

I had posted a problem about this before.... and proclaimed my victory after a tune up........ then back to the same issues the next day.

SO, i have replaced the idle position sensor. Cleaned the throttle body but not off the intake clean, but cleaned it.

also the tune up mentioned above.

and no codes, computer isn't throwing back any codes not sure if computer keeps track of this.

When first started for the day,it's ok..... idles a bit high and settles down once warmed up a bit...... so if i keep driving it around and not turn it off it seems to be ok for the most part..... sometimes once it gets up to normal operating temp. it will idle a bit low.

SO i turn it off and start it right back up last week at mechanic's shop and it works just fine of course.

most of the time if i go out and get back in it to go home etc. it either won't start without pushing on the gas, reving it a bit, or kinda driving with both feet.

When this thing acts up you can put it in drive and it idles so low it will learch forward bit at a time.

So if anyone has any ideas, let me know....... I would test for a vacuum leak but don't know how to do that.

Could it be a intermittent problem with the crank position sensor? I had that go bad before but usually the jeep just won't start or runs messed up.

I also can't understand the odd sometimes working behavior....... and no consistent problem to find a solution.

this isn't a 1986 jeep with a carb or something, so not sure whats going on, this sort of can't figure it out stuff should be behind us with OBDII etc? i dont intend to go on any sort of rant but this has been a problem for a long enough now.

ALMOST FORGOT: 2000 jeep cherokee 4.0L ( with the coil packs not regular ignition plug wires etc) ..... its a limited XJ trim, that shouldn't matter but thats what it is.

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You should do a quick list of what the tune up involved so everyone is caught up and can help. Is there any chance of you maybe getting video of what's going on? Sometimes sounds can help us figure out whats going on (IE are there clunks, is the idle unsteady, are there weird noises going on that match or don't match rpm?). Any chance there is a correlation between temperature and this issue?


video is a good idea...I will do my best to do that with equipment i have and edit it together so its not a 15min of video of nothing making sense..... ( THE QUICK LIST: tune up plugs only, it has no wires etc, used but working idle position sensor, cleaned the throttle body / plate etc which worked for awhile, but without taking it off the intake manifold, it sometimes idles rough, when idleing smooth that can be at a variation of steady low end RPMs, first startup of the day is fine but closer to 1,000RPM and drops down to normal after a bit.. usually runs pretty good until i turn it off... Sometimes after the 2nd start of the day or when it gets good and warm it will drop RPMs and catch it's self and bring them back up after feathering the throttle when starting it up after the first time of the day..... i think thats what has been done other then having good mechanic friend hook up the fancy computer to it which lead him to the idle position sensor).... it runs fine and strong i could drive it on the highway all day.


forgot the other half of comment: and yes once it starts up and gets warm it acts up "sometimes"....usually fine until i turn it off from 1st start of day.... no noises but fan for radiator is always on it seems (coolant level is normal but i did add coolent to he resivor thing but don't remember how long ago that was)..... it does make a small squeeking noise i have noticed, not sure if all the time, from the front of the engine but not sure what that is..... no "engine" clicking or other kinds of noises thou, it does seem to produce a significant amount of water vapor or whatever from exhaust and not sure if that is normal or not like most people not noticing these things before problems..... exhaust muffler leak.


Have you done a compression or leak down test? Troubles idling but ability to run at speed could be an indicator of the beginning of compression issues. Shutting off the engine allows heat to build up around the cylinder area and may be exaggerating compression issues?


No i haven't done that..... and i guess is should...... i can schedule that with my mechanic friend, just will take some time since he will be doing me a favor by doing this at a discounted rate etc. I have also read that my year cherokee had occasional problems with the head cracking? or something like that but i don't believe everything i read so not sure about that.


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What it sounds like to me is you have a vacuum leak. Idle bogging under load is a pretty common sign of a vac leak. Easy way to test for a vac leak without any gauges is to spray break parts cleaner or carb cleaner all over the motor while its running and when your idle jumps thats the area where your vac leak is at. If that doesn't work I would clean the sensor of your afm with afm cleaner NOT brake parts cleaner! Start with those two things and im 99% positive you will find your culprit and fix it!


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ehh, I actually sold it recently, However, i got a new battery and the problem became much better , after messing around with it, so a new battery fixed it " enough" for me.


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Well after going to the shop and running codes, and testing various things physically. The idle control motor is odd..... sometimes it responds to commands to raise the idle and sometimes it does not..... this weekend it ran (OK) but a bit rough and despite one of the comments normally the 4.0L runs smooth.......and then earlier this week the idle was bouncing up and down a bit........something new i guess.

It still has not been completely figured out yet....... I might have to drill a hole in the throttle plate or adjust the screw so the plate is slightly open, that is the current plan, i think one person suggested that and the friend i have suggested the same thing, at least that is the plan for now.

So its a work in progress just diagnosing it and i will update this once the solution is found/fixed and the jeep is running the way it used to.

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