Your idle is set by the ecu, not by the screw on the throttle body. That screw adjusts how far open the blade in the TB stays open. You can use a tuner to adjust your idle, but as far as eliminating the IAC valve? That's going to only cause more problems. Did you replace the IAC valve with a Ford Motorcraft one?

 

I've heard of people doing it as a temp solution. I wouldn't leave it like that permanently. Get a motorcraft IAC from rockauto.

 

removing the iac would be a bad idea imo, obviously there is a issue that needs to be addressed. I can only guess that if the iac wasnt plugged all your idle air would come from the tb side. now if you think about it thats probably not a bad thing and can function correctly because the air is still entering down into the plenum but from a different direction, but the underlying issue would be the main problem not getting fixed

 

No I mean like just disconnecting the IAC sensor to the IAC valve...not removing the whole IAC itself. The car runs absolutely phenomenal with the IAC unplugged but it runs like **** with it plugged it. Replaced with OEM IAC. I tried EVERYTHING to combat this issue. Took it to Ford. Everything. The idle is still hanging. I gave up.

Sent from my toilet

 

Honestly it sounds like you got a dud accufab. I had the same exact issue years ago with a hanging throttle and I replaced everything as well. It turned out to be a bad casting with the throttle body.

 

honestly, ive always had back luck installing throttle bodies, Im my car ive been running an accufab throttle but it never idle correctly.. stay at 1500rpm when driving ,then sometime drop down to 1100.. I did everything possible, changed IAC and so far ive made a delete gasket for the IAC, still plugged in so no check engine light but when its cold or I first start it I have to throttle it just a bit, not really a prob in summer. Ive tried everything and been running w/o IAC for a year now and its find, revs drop faster and always at 900rpm.

Ive been to 2 local mustang shops and cost me 80 $ each to diagnose and they couldnt find ****, guy kept telling me I need new IAC , even the new ones tend to fail.. He put a new one he had and no difference..


I think we have to same prob, even on my v6 when I got a BBK throttle body it never worked right .. I was lucky to have the stock thorttle body and it worked again

---------- Post added at 11:07 PM ---------- Previous post was at 11:01 PM ----------

I just hope it will still run without the IAC when I go and put force induction to it .. thts wht im scared of..

 

the problem will be a safety issue at idle, the iac was designed to allow a low idle at stop so your not working you breaks and such, if you throw other things into the mix u might have a uncontrollable idle at idle, the root problem needs to be identified somehow

 

Ive been running without IAC for a while now.. nothing will happen except bitch cold starts, tht car idles pefectly at 900rpm and 1000-1100 when driving.

 

All of this idle bullshit happened to me after I installed the Accufab ****, so the fact that it could be a dud is extremely possible. I think I'm going to run it without the IAC sensor connected for awhile until I can find a stock TB for really cheap...I've spent over $300 trying to fix this bullshit. Im not throwing another penny at this car for awhile. I only drive it 3k miles a year in warm weather so its no worry on cold start ups.

 

+1 , dont worry about running it w/o, but good luck finding the issue.. you lucky you have a gt, my stock throttle body messed up and had to get the accufab cuz couldnt find a stock unit.. never idled like it did when it was stock again..

 

hmm usually accufab is known for their stuff, i noticed huge improvements with mine, manufacture defects do happen though it really just depends on wheather your item was made on monday or friday

 

Yeah, very true. Thanks for the help guys. /thread

 

Did you try closing the throttle blade with the throttle stop screw? Sometimes you have to close them a little. I adjust the screw until the throttle starts to vacuum stick, them turn it open an 1/8th of a turn or so until the throttle stops sticking shut. I'd try that.

You basically want to get it to where you're using the IAC to control the idle speed instead of the throttle body. As far as idle taking a bit to come down, it can be adjusted in the tune.

 

Lol i got a stock one if you looking.

 

I can't see that it would hurt anything. You will loose your choke (that's why it won't run when cold), your high idle for accessories (maybe causing a stall out when the A/C's on), and high idle during braking and turns (causing the motor to stall in traffic). You will also loose all of the hanging rpms that were programmed into the ECU for environmental reasons. In my opinion you will loose more than you gain.

 

+1

My friend currently has is IACV blocked off with a piece of gasket and small piece of metal he cut into the shape of the sealing area. Still plugged in, but effective serves no purpose as it's blocked off. He has a ProProducts TB and Plenum. Has had idle issues since the swap. He has the idle screw set to have the TB slightly open.

My observation has revealed to me that
1.) His car idles at ~ 1000 RPM
2.) When he turns on the AC the idle drops to ~ 700 RPM and struggles. His off-idle throttle response is horrible with the AC on.
3.) I agree with the idle hang. His RPMs drop like a rock when he stops. Sometimes well below the normal 1000 RPM it idles at, then it struggles for a moment before it comes back up, or continues to drop and kills the engine.

I can't speak for warmup as I haven't seen how it acts pre-warmup. We swapped IACV's to cancel out that being the culprit. My car ran perfectly fine with his IACV. His continued to run horribly with my IACV.

:headscratcher:

 

OP, did you try the IAC restrictor mod?