Mike12086

after a little playing this weekend i found that if i unplug the temp sensor once at operating temp it will bring the idle back up to 750 with very minimal bounce (but still a bit rough). so what sensor am i missing open vs closed loop that might still be giving me the low idle?

tiwvr1

just replace cps, they go bad all the time, good prevenitive maintaince. My jeep would do it when it was hot, it affects timing, wouldn't always cause it to stall, mine actually never stalled because of it, just rough idle.

Mike12086

thats what i was looking for..every other thing about the cps i read metioned stalling which i dont have...next part to be replaced CPS.

Mike12086

changed CPS...no difference

tiwvr1

damn, that fixed it for me

tiwvr1

just re read all your post. The IAC will only operate when it is in open loop or the ac is on (I think) IF it is not throwing a code pull the IAC and clean it real well, but don't be forcefull with it, Just lighty try to wipe the carbon away witha brass brush, or a rag. Make sure to clean the seat well in the TB. plug it all back together, reset computer and hold in drive with brake on, at idle for 5 min or so. See if that works, if it doesn't you may have to go with your first guess, a comp.

Bustedback

The IAC is always adjusting to maintain a constant idle speed and it does not always set a code when it fails. When you drive the IAC closes until you take your foot off of the pedal.

Mike12086

well i think i might be onto something. Just did a compression test.

1 - 120
2 - 110
3 - 112
4 - 155
5 - 155
6 - 140

Number 3 came up to 145 once oil was put in, others did not change. Another wired thing i noticed was that when i finished the compression check on #2 and went to #3 upon the first crank something blew out of #2 (puff of something, happened both dry and with oil).

I bought some of that Auto-rx stuff to try and see if that will help any of the seals out. Also after reading around, at idle the oil pressure gauge is high(a little above the 40 mark). i read that this should be lower at idle but i also read that the sending units are known failures. i figure maybe there is alot of buildup in the engine and hopefully that auto-rx will clean it out. now to play the waiting game until it comes in.

sdmf001

What have you gotten so far?? is it running better and what did you do? I've got a 98 grand Cherkee and it is doing much the same.

freegdr

did you ever clean the iac motor and the hole it m ounts in

Mike12086

I'm about 1800 miles into the cleaning phase and dont seem to notice any difference yet. Once i hit 2500 and change the oil i plan to do a cpmpression test and see what if anything has changed yet.

Mike12086

That was one of the first things done, pulled the whole throttle body out and gave it a good cleaning.

96jeepcrawler

does your gc when you put it in reverse lose idle really fast?

Mike12086

nope

96jeepcrawler

mine got the same problem as yours but it misses like a sob and loses idle in reverse and drive