ok so my truck always idles different. i have my iac unplugged and my TP screw all the way unscrewed. i know something is not right but i cant figure out what it is? ive replaced the IAC and the cam sensor...both were throwing codes. neither helped. and i reset the pcm. and did the whole unhook battery with heads on ect. any way it usually idles around 600 when cold....and about 1100 to 1400 when warm. so one day i pull in the drive way and its idling at like 1500. so i decided to clean everything and reset the pcm. i turned on the heads and disconnected the batt and then touched the pos and neg cables together for a couple of seconds. then i cleaned the TB IAC and MAF. when i put it back together it idled at like 1600. and wont really go down or any thing like it used to. i started messing with the iac. i pulled it off and tried to start the truck...it just stalled. so then i made a plate that bolted where the iac is and covered the holes completely. the truck idles around 1300 like this...is this safe?

 

that sounds way high to me my truck idles around 700

 

also shouldn't the truck stall with no air going throught the iac.....cause i remember when i did this at first i made the small hole too small and it would stall out...how is it staying running with no air?

iac restrictor plate

 

hey..i just realized this but do u think i could have a leak where the intake bolts onto the motor? ive had that off with in the last year but i cant remember if that's when it started idling funny or not? is there any way i could like pressurize the intake and see if it goes down? it seems like if it will run with no air going through the iac then its getting air form somewhere. and with the TPS screw all the way unscrewed i don't think its coming through the throttle body. what to do u think? thanks

 

BIG air leak behind your throttle plate such as intake manifold is leaking at a gasket. take it to a shop and get the intake smoke tested that should find the leak!

 

also what would make it idle lower when cold and higher when warm?

 

Sounds like you have a vacuum leak...which usually is accompanied by a bank1/2 lean code. You could do what Hanks suggests...

Personally, I'd leave it idle (with your screw back in place of course) and shoot some brake clean around places where it could be leaking (if I couldn't hear it)...not that that is a safe method, as there is a risk of fire, but I've never caught anything on fire like that.

Normally, probably 99.99% of the time when an IAC goes bad, the truck just won't idle at all, and will instead stall. I've never really seen the IAC cause the idle to go too high.

 

hard to say but it would cause a high idle because its lean.... i don't remember how those achieve their choke circuit per say. but that would be my guess is an intake leak. I had an issue like that and it turned out to be an elbow on my pvc return theirs a thread on it somewhere here, I'll find it

 

https://www.ranger-forums.com/f15/fi...1-po174-87334/

 

ok cool...and ive tried that carb cleaner thing to no luck....ive also unplugged a small vacuum line ...like the one going into the egr valve and sprayed carb cleaner right into it basically and it didnt do any thing...not sure why but the only line i can get to really make a difference on how the motor runs it the one on the brake booster...

 

hrmm...well you may have a pretty big vacuum leak then...because technically, if you sprayed that stuff directly into a vacuum line it should have changed idle or bogged down or revved up...unless of course you assume that the air coming into the engine follows the path of least resistance, which it does. So when you used a bigger opening, it sucked right in. My money is on unmetered air entering the engine at some point along the way.