Hey guys, I have a few quick qeustions. What is supposed to happen when you unplug the IAC? Is the truck supposed to quit, or is the idle supposed to drop?

How long after you unplug the IAC should something happen?

First why are you wanting to unplug it?

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The truck is idling like crap again. It's idling at about 400-600 at stoplights. At one instance, it started to idle really high upwards towards 2K all by itself. I remember somebody said something about unplugging the IAC as a way to check to see if it's working, but I don't know if that's actually effective or not. Last time this happened, I replaced the IAC with a used one, and the idle improved. I'm trying to rule out the IAC to see if something else is to blame or if something is causing the IAC to fail. I find it strange that two would fail like this.

The IAC only works to let air in when the engine is under load at idle like if you have the ac on. Does it do the same thing with truck running and air off?

A new IAC is not cheap so replacing with new would be a gamble.

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The A/C was off today due to the cold snap. The heater was on though.

Would holding the brakes be a load on the engine/IAC? It runs great any other time except when it idles. I'd take it to Ford, but they want $90 just to hook it up to a scanner. That's ridiculous IMO.

dude... if you had the problem where your truck would idle at close to 2000 RPM's then yeah the IAC is the problem.. the IAC has a little valve in it that opens and closes automagically when the computer senses a increase in needed air... its a frequent problem with ford engines for them to get stuck in either a open or closed postion... or even somewhere inbetween.. it sucks but a new one would be the cure.. of course the CEL (check engine light) should come on but it always doesn't have too

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2009 ford ranger Sport 4.0L V6/2 8" red hot glasspacks swept side before rear tire/2 catco high flow cats/K&N 77 series intake system/BFG all terrain 31x10.5x15 tires/Procomp 98 series rock crawler black rims/westin black sportsman brush guard/6-6'' Hella 500FF lights/black rhinoliner/Bilstein 5100 shocks/uniden 68LTW CB radio/Fx4 skid plates/cranked Tbars/autometer vaccum, Camper shell with thule roof rack/ belltech shackles/Pioneer headunit with pioneer speakers with Kicker 10'' sub

I believe if it was stuck open it wont throw the CEL only if it was stuck closed.

I have to agree a new IAC is the solution. Getting a IAC from a junkyard is a waste of time and money.

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Unplugging it will make the idle drop. almost to the point of not running. It will sound like it is cammed. Mine went out and was reving high between shifts, I unplugged it and then adjusted out the tiny screw underneath the throttle body to bring the idle back up until I could get a new IAC

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Alright guys, i'm gonna keep this short. I put a new IAC on, and the truck seems to be running fine now. No shutter at stops or lights, or anything like that. The real test will be tomorrow on the way to school.

I opted for the one from Auto Zone, because I had to take care of some other things, and $107 from Ford wasn't in my budget. In January I have a big job coming up, so I'll be heading to Ford for an IAC as well as the Cam Sync so I can have them when I need them. For now though, the Auto Zone IAC has a 2 year warranty, so should something go wrong with this one, I can replace it for the next two years. I only need it to last until January though.

Thanks for all the help guys!

if your IAC was bad and you unplugged it, nothing would happen. If its good, the idle should drop or the truck will shut off. Its in the Hayne's Manual.

Oh, well nothing happened, so I guess it was bad. That's why I originally asked because I thought the idle was supposed to drop.