Waynerd

98 xj,4.0,aw4. A while back it cut out on takeoff. Only did it once. Fast forward a few weeks and I was parked overnight on a incline nose up. Next day it would idle around 1600 once I started driving. Then it started with cutting out like it wasn't getting fuel. I did this for the weekend then it stopped the high idle but would still cut out sometimes when first taking off. Tuesday it actually stalled as I was backing out of a parking space but fired back up.
So last night I switched out the TPS with one from another xj. Took it for a drive and still did a little cutting out when I would first start it and try to takeoff. So I. Leaned the IAC really well and the hole it goes in. Started fine but didn't test drive.
This morning I did the PCM reset. Fired up and idled fine. I go to leave for work and it turns over long but no start. Second attempt won't turn over. Realize positive clamp wasn't tight enough. Tighten it and it starts but won't idle at first like battery was dead. Got it to idle and drove to work fine.
Now at lunch time I go to leave work and it tries to start but won't until I work the pedal. Need to rev it a bit before it idles on its own. Go home have lunch and go to head back and same thing. Won't start without working the pedal just right. On the way back it begins idling high again.
So that's up to the moment. Could the IAC be bad? I wiggled vac lines when it was idling normal yesterday and couldn't get it to idle high. Also sprayed around them and throttle body with throttle body cleaner with no indication of a leak. Any ideas here? Starting to think about selling the heep. Something else keeps going wrong before I can even fix the first problems with this dang thing.

Oswalla

I would rule out failing fuel pump with a pressure test at the least.

Martlor13

It's almost 20 years old what do you expect. Don't sell it just because of a few problems. All jeeps have problems. You haven't made a real "attempt" at even diagnosing or fixing this problem. Check it out more and see what's wrong before you sell just because of a few problems that every vehicle this old encounters

Bustedback

You cleaned the IAC, you replace it. Cleaning it doesn't last very long.

tjwalker

Have you seen a check engine light? Even if the answer is no, I would still recommend that you scan the computer to see if you have any "pending codes". You'll need a scan tool or a code reader. Autozone I believe still reads codes for free.

If there is a code, that makes tracking down root cause one heck of a lot easier.

Waynerd

Guess I'll try another IAC. I have two parts jeeps and another I could try. I didn't even think about running the scanner on it because the light is always on for a misfire from a valve or valve train issue. Cylinder one has decent compression but leak down was not too good. That's the thing I have doors a hood a hatch a headliner to install. I need to finish the control arm bushings. Just realized the ball joints either weren't pressed in fully or are shot or knuckles are shot. Still need to pop the head off and figure out the issue with that. Now this issue. That's all on top of other stuff I've already done. For every one thing I fix three more problems arise. I have another 98 I need to put full interior into. Maybe just swap registration to that one for now. I'll post later with results.

Waynerd

Dang. Thanks TJ for reminding me to use my scanner. Getting p0123. TPS voltage too high. So wouldn't you know it I do a google search and it turns out a bad clock spring may cause short to horn or cruise supply wire which could give a false p0123 and cause similar issues as mine. Ruling out a bad TPS here just because I tried a known good one. I'll check my harness to the TPS just to be sure but I definitely have a bad clock spring and it may be causing it. I pulled the fuse and the relay to my horn to see if that changes anything. Also will have to test the TPS with a multi meter just to verify.

Waynerd

Drove it a few miles last night. No symptoms or CEL yet. It seems to be running better than it has since I've owned it.

Waynerd

Right after I posted last time I went to leave for work and CLICK! Need to replace battery and cables soon. Still no CEL or high idle or cutting out though. I need to go through the grounds I guess and do the battery and cables before I can take it any farther. Then the clock spring and I should be golden.