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anklenawer 12-24-2011 04:29 PM

91 High Idle at start, and increases with time
initial cold morning start - idles at 1000, then ceps creeping - but hits 1500 in about 5 seconds... then throughout the day it will hit almost 2000. checked vacuum lines with nothing - i sprayed cleaner all over - manifold and all - not sure

... about 1 foot from the headers, where 2 pipes become 1... there seems to be a crack, but i sprayed TB cleaner on it and no change - i really don't think it is a vacuum leak... cleaned the IAC, and TB - no difference .. also - just bought a TPS, can't get the last screw out!! haha - ill get it over time i guess.. broke two T20 bits already - its crazy...

anyway- get back to me if you have any more ideas, can you adjust the idle on a fuel injected jeep? hum....

thanks guys!! happy holidays



Garyk 12-24-2011 04:45 PM

Sounds like a vacuum leak. Check the can do this by carefully spraying carb cleaner along the port areas when engine is warm and at idle, if it changes, there is where the leak is.
Aslo double check the rubber boots at the intake where the vacuum lines are connected, all it takes is a fine crack...I found mine on the bottom of a boot, could not see it until I pulled it off and checked it carefully.
I found it a lot easier to work on the IAC and TPS by removing the throttle body and working on a bench.
Idle is set by the computer.
It could be a bad IAC or sensor.
Have you checked for codes?

anklenawer 12-24-2011 04:54 PM

no, i haven't checked for codes, i just got to VA. i might buy a code reader but didn't really think to do so yet.

ill take off the TB if i can't PB blaster the TPS off.. maybe i should get an IAC too ( just incase)

ill go through again and check vacuum lines... and check boots. there is one line i know that is bad, but when i plugged it, no change ( the thin line goes to the top of the charcoal canister..) and the other larger ( maybe 1/2'' line on top) line leaving the canister is pretty busted too...

thanks for the help man

anklenawer 12-24-2011 07:03 PM

alright everyone - i just went through and checked almost every line... ill take a picture tomorrow if i get a chance, but one line ( as stated before) very thin line to the top of the charcoal canister, was bad, so i found it and plugged it - no difference -

and in summary - i sprayed the hell out of everything and i couldn't find anything as far as vacuum leaks, the manifold areas, pcv valve, throttle body, vacuum lines to and from...

I'm taking the throttle body off tomorrow ( christmas - maybe next day) to take off the TPS, and clean it all up too.. but hopefully thats sounds like a vacuum leak, and if the IAC/TPS isn't the issue, i dreadfully am going to take this in to a shop ( any one around Viginia Beach Area to help???)

thanks a lot guys, ill keep this posted and updated for anyone else who has this issue...

any other ideas keep me posted



NW_YJ 12-24-2011 07:16 PM

I had that issue a while back, took it in for a diagnostic, ended up being my TPS.

anklenawer 12-24-2011 07:33 PM

merry christmas - putting it in tomorrow regardless of my knuckles, or santa!!!\

im pumped man - thanks

mixedup4x4 12-24-2011 07:49 PM

I had the same issue, was the TPS

anklenawer 12-24-2011 08:14 PM

thanks man - hope thats it...

glad for everyone to help

merry christmas...

anklenawer 12-25-2011 01:31 PM

alright - merry christmas -

replaced the TPS ( took off TB and cleaned everything) - started up - SAME THING

was not the TPS... I'm going to replace the IAC tomorrow and see if that does it... other than that i think i am going to adjust the idle... i'm 90% sure it is not a vacuum leak, did a through tbcleaner check ( around TB since i took it off) and no high/low revs while spraying...

anyway - ill keep this post updated...

thanks again for the help - any other suggestions - anyone wanna make a bet its the IAC?



mixedup4x4 12-25-2011 03:11 PM

Could be IAC

anklenawer 12-26-2011 12:29 PM


This morning i put in the new IAC. it looked a little different ( metal not plastic) but i compared it to the old one and specs were good.

IMPORTANT - i read the instructions ( out of character) and it said that if the length of the pintle from the o-ring was more than 1 1/8'' to adjust it, i tried to adjust my old one, and wouldn't move ( hint that i found the problem)

read that also to reset the ECM you have to be at operating temp, and at 40 mph...

How it Went Down!:

Replaced IAC, Idled at 3000rpms ( highest ever) - i got nervous and unhappy

Drove to 45mph at operating temp for about 10 min - still idled at about 2000 ( still unhappy)

parked in my driveway while idling to think of problems.. then magic happened....

by itself just at idle, it would slowly skip down rpms ( by about 300....then back up a few, then down)
until it reached a beautiful 600-700 rpms... and it stayed there.. drove it around again - still at a good idle

thanks for everything guys.... i appreciate the help

kyle - Happy Holidays

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