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Michael_Price1990 01-26-2013 01:21 PM

Idle Problem! Bad IAC i think. Tips?
Alright. so i think i know what the issue is. but before i rip it apart. i want to make this post. it would suck to go through all this work to find out i was wrong and it may have been a way easier fix.

My 2003 SVT focus is at a high idle. 2000-3000 rpm. if i disconnect the battery and reconnect it, it drives right for about 2 days then its right back. i have checked the vacuum lines which i replaced all of when i put on my supercharger about 3 months ago. and there all still connected properly and i see no leaks. so what ive come down to is the IAC. i know i can try cleaning it, or just replace it. but i want to make sure im on the right track first.

for those of you familiar with the Jackson Racing Super Charger.. you know its not easy to get to the back bolt on the IAC. i believe i have to remove the supercharger just to get the damn thing off. and i would have to go to my dads place to do that. so i would hate to go through all this work just to find out im wrong..

Any one have any suggestions? the car Drives Great, besides the fact that in 1st gear in a parking lot it goes 15mph by itself. so i'm riding the breaks. sometimes it takes a few seconds to start and days like today it started right away. high idle is consistent. however, when i disconnect the IAC harness. idles down where it should be and revs great. but while running, if i plug it back in, It instantly goes back to high idle and another thing that i forgot to mention is the intake is real loud sucking in air like a high pitched vacuum. but when i disconnect the IAC this all goes away. can i drive with it unplugged? i haven't tried. is it really needed? i know its idle air control but it seems to work better without it at the moment.. id like to wait till its warmer out (living in Colorado) if possible. if that's even the issue. but if its serious ill get it fixed this weekend.

could it be something els?
No check engine lights.

Michael_Price1990 01-26-2013 01:53 PM


whynotthinkwhynot 01-26-2013 02:27 PM

Eh, do you have a way to monitor your A/F ratio?

You might want to post over in the FI forum, and provide a link to this thread. It sounds to me like you have some sort of leak in the IAC body. When you disconnect it, it should force the plunger closed through the spring action cutting off air to the leak. It's probably the vent for the diaphragm that is leaking, so yes, you just need a new one.

The diaphragm dent is that little button that is on top of the IAC, you might be able to feel your vacuum leak there if you can get your hand on it.

Michael_Price1990 01-26-2013 02:55 PM

well damn. i wish it was easier to get off the supercharger. ill have to check that in a bit. is it safe to drive with it unplugged?

emsvitil 01-26-2013 03:49 PM

You can just get to the IAC from underneath on the stock intake manifold.

Does the supercharger replace the stock intake manifold?

whynotthinkwhynot 01-26-2013 04:26 PM

If you haven't blown it up yet, it should be safe to drive with the IAC unplugged. It might not want to stay running in the morning without being driven- and your idle will likely be high, but that's about it.

It should be safe, but like I said, I'd open a thread in the FI forum, and then put a link to this thread in there so those guys can look at it. I'm not an FI expert.

Michael_Price1990 01-27-2013 12:01 PM

alright will do, and yes. the supercharger removed and deleted the factory EGR system and complete intake manifold setup. at the moment i wish it was stock since it was way easier to get to before. lol

focuzed1 01-28-2013 09:38 PM

just disconnect the iac and turn the adjustment screw up a bit on your tb. I have been running that way on a 400+whp focus for years. the iac is only for when you turn on the ac it raises the idle so you dont bog it down due to increased load. so just turn up your idle manually a bit think i set mine to 1k and then when i turn on the ac it only drops to stock idle around 700 or so.. works perfect.

whynotthinkwhynot 01-29-2013 05:15 AM

I did mention that if you can unplug the IAC and it runs better- then that is a sign that the IAC is the problem, right? I suggest getting an IAC from our vendor Village Ford, and not disassembling anything until you can change it out. I'd run it with the IAC unplugged like you have it until I could replace the part.

Village Ford

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