Can any one tell me where the IAC sensor is located....i am having trouble with my truck....

 

What engine? On the 4.2L and 4.6L, its right on the side of the throttle body. Its a silver canister about 3-4 inches long, held on by two 5/16" (I think?) bolts, with a plug coming out the back.

On the 5.4L, its the same canister, but its located on the very back of the throttle body elbow, in front of the firewall, on the passenger side. Its tough to get to.

 

Hey, I have the 5.4 Liter, and this won't be much use to you if you don't have one. But I know I searched forever trying to find someone who'd give me picture's. So if that's the case, here you go, if not. Oh well...





Good luck, peace

 

Flareford150,
I just wanna say that your post is exemplary. I'm a forum veteran and I get so annoyed at people posting half@$$ information and stupid instructions for those in need, but your post showing the pix of the IAC are perfect and should be applauded. I, unfortunately, had the displeasure of leaving work early, twice today due to my wife's IAC being gummed up and since I've not had to deal with that part on any of my vehicle's, I was momentarily stumped. Once I was led to the likely culprit (truck would start but would die upon resumption of idle), my CDROM manual showed the IAC to be right on top of the TB, which was a LIE!! Stupid thing...Was the IAC on top in earlier models? Anyway, I searched here and found your post and after work, I got it cleaned and replaced in about 40 minutes. Not bad for a pharmacist with pansy@$$ hands. LOL!
Thanks again dude!!!

 

Thanks to this forum and this thread in particular for saving me hundreds of dollars. Because of the info in this and other threads I was able to determine that my sudden, chronic stalling problem was the IAC valve. Flareford, your great photos helped me immensely.

$39.99 at O'Reilly's and a few hours later and my truck is idling smooth at 750 rpm. As a caveat to anyone attempting this repair, the bolts holding this thing on are like butter, and the top one is nearly impossible to get to. I rounded the head off in no time flat and ended up grinding it off with my Dremel. Once I did that it went back together in minutes.

Thanks to everyone who posted on this topic!!

 

What is the IAC?

 

I believe IAC stands for "Intake Air Control" valve. All multi-port fuel injected engines use one. It basically meters air around the (closed) throttle body to regulate engine idle speed.

 

Like I said in my post, on the 4.6L and 4.2L engines, its right there by the throttle body. So your CD was not lying, you just looked up the wrong engine it sounds like.

 

IAC stands for idle air control.

would this sensor be bad on my truck? 89 302.

in park or neutral the motor is kinda stuck at a high idle, while when the trans is in reverse or drive, the rev's aren't so high. it gets pretty annoying with the motor revved up like it does in park/neutral and not able to hear anything outside anywhere near the truck...lol

 

I replaced the IAC on my 2001 Supercrew with a 5.4 liter the other week and found that a flex socket or universal joint adapters for your 8mm socket comes in real handy getting tose bolts out.

 

the iac is not actually a sensor, it's a servo type valve that lets more or less air past the throttle plate to keep the idle at a set rate.

i know i might be getting technical here but people sometimes get confused thinking that this part will fix all idle problems. i've heard of people replacing them 3 or 4 times thinking that could be the only reason for an idle problem. all efi engines have an iac they do wear out and get gummed up.

 

Hey guys with IAC experience....can they whistle? I described the whistle noise I have been posting about to my dealership's head tech and he said it could be coming from or aruond the IAC since it is right behind the firewall (5.4). That makes sense becasue I only hear it when I let off the gas after accelerating. HE says the IAC adjusts to keep the engine from stalling or backfiring under those conditions. Anyway, just thought I'd run this by some of you guys who know more about IACs than I do. Oh by the way, sorry for hijacking the thread (at least I didn't change the topic)

 

Yeah, they can whistle. On the Contour 2.5, they can sound like a moose. That will really wake up the neighborhood.

The dealership tech is correct. That is called the dashpot function and performs the same feature as does the dashpot on carbs.

Bluneon: Yes, the IAC could be your problem. So could any vacuum leak. You can try cleaning the valve, sometimes it helps. Throttle body cleaner works great.

Steve

 

Thanks for the response. If the IAC is in fact whistling, is this a problem or is it ok as is? The truck idles just fine and doesn't appear to have any sort of vacuum leak. Could the whistling be a minute leak that the PCM isn't detecting or could it just be dirty?
I did try spraying some throttle body cleaner in the throttle body and that didn't help. Last night I happened to be flipping through my Chilton's manual and noticed it says NOT to clean the throttle bodies because they are coated with some sort of protective coating. Oops. Hope I didn't do any damage. Anyway, would it be worth cleaning the IAC, replacing it, or just leaving it go? Thanks again.