Ok its been a wile since i have been on. I got my build done and have been enjoying the car for a few months. Tuesday morning my idle was high and is remaining to be so. I have checked for vac leaks, tps voltage is good at close to .55, checked the timing, and set the iac twice just to make sure. But this thing is just determined to idle at 1,100 no mater what i do. when i go into diagnostics i notice i can hear a faint clicking from the iac is this normal or a sign that i should replace it? thanks for your time.


Ok i changed and reset the iac. Seems to have cured the problem I'll speak again if it returns....

 

Ok after i reset everything and replaced the iac i drove the car for about 45 to an hour and all was well. Got up for work this morning and as soon as the engine was warm it went back up to 1100 for idle. So now i'm stumped i have checked for every logical thing any help would be awesome.

 

i know this sounds stupid but let the car start from a roll and get on the throttle enough to make the tires spin and see what happens.

 

where did you get the iac from? its possible that you got another faulty iac, or there is something causing them to go bad right away?

 

i got it from the zone don't know bout the quality. It idles fine and normal until everything is up to temp i can just be sitting in traffic and it will be normal ten it gets unstable and then it goes to about 1100 and stays untill the car cools again.

 

ok heres my advice from working in a automotive shop full time since i graduated highschool, never... and i repeat NEVER buy autozone parts.

the other day i put a autozone master cylinder on my car (horrrrible idea) and it would leak the fluid out of the resivor in 2 days... over night there would be a 6+" diameter puddle on the ground underneath my master.

buy a IAC from AC Delco or somewhere that doesnt have crap parts, that will probably fix your problem.

 

But I don't think that's your problem.
Your computer will try to idle at 1050 if it thinks the engine is -4C or lower. What temperature does your ECM think the engine running at?

 

Well i have bought plenty of zone parts over 10 years and never had to many problems with em. as for the temp I'm not sure cause i have no scanner it would be the sender near the thermo housing right? Any chance i could look for a certain ohm load there?

 

Check your vacuum lines

 

Changed the temp sender cause it was cheap and since it has been cooler out the problem takes longer to surface. But it is still there as soon as the car is in closed loop it idles up. I checked for vac leaks again still none surfaced. Checked the mass air flow relays and they seem to be good to me about to check the voltage from the meter itself even though i think its a long shot. Still no codes to help any more ideas?

 

Ok as it turned out the burn off relay was in fact bad and i'm guessing it has been for some time now. i tested the mass air flow and it had good voltage but when i tried to read the hertz I couldn't get a reading given it was before i replaced the relay. So is it likely that the sensor is ruined and the car is in some limp mode that is causing my strange idle upon operating temp?

 

Up untill now i haven't thought to check out my injectors because they are only a few months old. This morning i checked them cold and they all checked out. When i got home from work and everything was flaming hot i checked again. Five at around 18.5, two at 13.5, and one at 15.5. The 3 that are off happen to be on the right bank so it would not triger a rich or lean problem. I'm unsure on how this would effect the idle speed but it dose seem the fluctuation only comes on when things are hot. Any thoughts?

 

i was dealing with the same problem recently had gm resett the iac twice..... still failed, have you cleaned the iac housing? i took mine off and had a lot of build up soaked it tb cleaner and scrubed and scrubd till it was clean then soaked the iac valve too put it back together and havent had a problem since... so try and see if that works for you. if you had an injector problem your idle would be erractic.

 

Another update. I have now replaced Temp sender, changed the zone iac for a quatlity new unit, O2, MAF relays and MAF, Found frayed wiring at the air temp sensor so i replaced the pigtail and sensor, searched all wiring for damage and checked grounds, removed and cleaned the TB and Iac housing. So i went by a local mechanic shop to scan it and the scaner says it cant comunicate... The mechanic says ha thinks his pigtail is bad. So i removed and pluged the vac port to my egr and go for a long drive, i get most of the results i expected alot of rattle with a medium load and generaly bad manners at constant speeds. I however did not get a check engine light so i unpluged a few other things that i think should throw a light and nothing. Check for codes and once again nothing stored. The colder it is out the longer the idle takes to pick up but as soon as underhood (Or ECM?)temps get hot it starts again. I have checked everything i can find a way to check and am feeling somewhat defeated by this thing now. Sorry about how long this is but i gotta get my baby satisfied!

 

It was the computer. Replaced it and she is a champ again. Thought it was strange that it gave none of the normal warning signs. Thanks for the thoughts.