[Red95_5Oh]

Hello all,

I have been trying to fix this problem forever now. The RPM's have been shooting up between shifts, and sometimes hanging at around 2.8,2.9k RPM's. I replaced the iac under warranty at autozone. It seemed to stop and idle correctly. Then it started to hang for frequently even if it was in gear it would pull the car along. You can hear air being sucked through the intake (it is a cold air fender well, similar to summit racing one) even after the throttle plate had closed. I have cleaned the TB and airway passages. I have done the idle reset and everything too. It idles great. Doesn't bounce or anything. Just when in motion and shifting gears. The only way to not have it happen (as long as i am not driving around 2.8, 2.9k rpms) is to let off the throttle, then let the engine chill for a couple seconds then shift and rpms will drop normally.

I unplugged the IAC and engine ran great. Only problem was morning when engines cold it would die because the IAC wasn't giving it more air.

I plugged the iac back in earlier, reset the screw thats next to it to 2.5 turns out. What is that screw called, and how do I set it correctly? Seems idle shoots up still, but drops without hanging mostly.

Do I need an IAC? When IAC was not plugged in, when engine braking, i would hear a pop pop pop pop, from my exhaust. I am assuming unburnt fuel was igniting in exhaust manifold.

[Red95_5Oh]

A new Ford Motorcraft IAC from a good parts store is 180 bucks... I know a guy who knows a guy who can get it for 108... times are tight right now. Will just leaving it unplugged harm anything till I can get a motorcraft IAC?

[furreal302]

I had a weird idle issue over the summer... it was different than you describe but that doesn't matter. I tried leaving the IAC unplugged and manually setting the idle to stay at a solid 900. That didn't help.
I found out that my problem was a cracked rubber grommet for the air intake temp sensor, behind the MAF. I had more problems than just a shit idle. My plugs were fouling, the engine overheated under load, crap performance. I couldn't figure it out until I pulled off the air intake and saw the rubber grommet was shot. $0.59 later all of my problems was fixed.

My RPMs either shot up or stuck while shifting when I had the auto engine controller in there too but I doubt that's your problem.

[ryanw]

check for vacuum leaks

also if you un bolt IAC you can try cleaning it out with carb cleaner, cuz you get carbo build up in there,... but dont get any on the electrical

[Red95_5Oh]

Originally Posted by ryanw check for vacuum leaks also if you un bolt IAC you can try cleaning it out with carb cleaner, cuz you get carbo build up in there,... but dont get any on the electrical

From my CAI filter, to my lower intake manifold has been cleaned to perfection. Nooooooooo vac leaks at all. ANYWHERE left fender, right fender, top bottom middle.

I will pull one or two of my plugs tomorrow and check them out. I am lazy as hell with certain things... pulling plugs... is like 3 of them.

What sensors determine that the car is not moving... basically what would tell the car to turn the IAC on at 3k rpms. That ladies and gentlemen... is the million peso question.