Guess my idle issue is still present.

Okay, first off it's a 90 4.0/auto and has

New:

IAC (plus a cleaned port)
cap/rotor
wires
plugs
Complete Renix vac. harness
air fliter
fuel filter

I adjusted the TPS to 83% as per the manual and no vac leaks that I know of.

For those of you that remember what is was doing, well I finally got it to this point.

Revs to 2-2.5K on start and holds for a couple of seconds, then drops to 600RPM and idles there. Pretty smooth idle, no weird fluctuations, and it was always at 600.

Now, a week later it stuck on 3K RPM's on start up on me. I had to shut it off and start it again to get them to drop. The idle is also up to 1K. Then later at the post office it stuck again at 3K. Shut it off and started it 4 or 5 times and it finally dropped. Got it home and shut it off. Restarted it and it reved to 3K then dropped to 1K.

I shut the battery power off and on and fired it back up. Reved to 3K and dropped to 600.

The IAC should not make it rev that high correct?

I'm thnking the TPS at this point, just wnat to see what you guys think before I drop $50. I tried to liberate the one from the parts truck but one screw snapped and the other stripped. I need that to be a running rig for now so I don't dare snap the stripped screw.

the only time my 89 went to 3000 rpms and stayed there was when i installed and adjusted to spec a new tps. it happened on a moist humid morning while driving to work when i pushed in the clutch. when i got to work i disconnected the wiring, reconnected and readjusted the tps to spec(still had the meter in the xj)

i dont know if it was from the unusally moist humid air(rained the previous night) and the tps got moisture in it or the wiring harness, or if it came out of adjustment.

well I pulled the plugs (for the TPS) and they look good. No moisture, crud or corrosion. Check the TPS with my voltmeter and it is still adjusted correcly.

I just fired it up, and it reved to 2800, held for a bit then dropped to 600. Shut it off and restarted it. Reved to 3000, held for a bit then dropped to 2000, held for a bit then dropped to 600. I'm going to try a new TPS and if that does not fix it then this thing is 100% for sale at the end of the driveway. I can't keep dumping $50-100 a week into this thing (it's one of my dds).

adjust the tps to 12% thats the spec. check the ground wires at the dipstick also

jneary said:

adjust the tps to 12% thats the spec. check the ground wires at the dipstick also

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my manual says 83% for the renix

Yeah, isn't 12% for manuals or something like that?

KaiserMan said:

Yeah, isn't 12% for manuals or something like that?

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are you sure i thught the ECM were the same

do it your way.

Erik Litchy said:

are you sure i thught the ECM were the same

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That 83% is at the TCU side of the TPS, which a manual obviously doesn't have.

Vacuum leaks maybe? Either in the intake or vac system...

I had a some loose bolts on my intake manifold, tightened then up and that vac leak went away. I've tried to isolate anything that could leak vacuum and have found no leaks so far.

Take a propane torch and go around anything that can leak. Obviously with gas on and not lit. Change in idle shows leak. You can also find this method on youtube.

winterbeater said:

Take a propane torch and go around anything that can leak. Obviously with gas on and not lit. Change in idle shows leak. You can also find this method on youtube.

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x2 I was just about to type that.

a vacuum leak wouldnt be intermittent. chryslers specs are 12% tps adjustment. if your doing it on the other connector then 88%.

it really sounds like iac just take it out and move it around. and then put it back in and see if that fixes it mine will run fine for a week or so untill it starts to rev at 3000 and whenever i take the iac out and move it around it will stop for a few weeks

bigkeegs said:

it really sounds like iac just take it out and move it around. and then put it back in and see if that fixes it mine will run fine for a week or so untill it starts to rev at 3000 and whenever i take the iac out and move it around it will stop for a few weeks

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Ignorance alert! What's IAS? I got all the other acronyms, just not that one.

IAC....Idle Air Control Valve

smcdonaldaz said:

Ignorance alert! What's IAS? I got all the other acronyms, just not that one.

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i didnt say IAS i said IAC and your ignorant for posting that comment

^ Easy with the name calling there keegs. The "Ignorance alert!" was (I believe) him stating that he's ignorant as to the meaning of IAC and mis-typed IAS.

p.s.
Your ignorance is showing. In the context of your post, you should have typed "you're" instead of "your." When referring to yourself, it is "I" not "i."

Back OT. I'm nearly convinced that this problem was intentional on the part of Jeep (to what end I cannot guess). I've tried most of the suggested fixes I've read on this board to no avail. Mine usually stalls first (at very low speeds), but it sometimes does it on initial start-up. It's annoying at best and dangerous at worst (in traffic on the freeway).

kujito said:

^ Easy with the name calling there keegs. The "Ignorance alert!" was (I believe) him stating that he's ignorant as to the meaning of IAC and mis-typed IAS.

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That's what I got from it.

Anyway, the IAC is new and both it and the new one work (I've pulled them to both when they where in and out).

I ordered the new TPS today. I get a discount with my NAPA. $38 my cost. For that cheap it can't hurt to try.

I'll play around with the IAC again just to make sure though.