My friend is having a problem with his truck dieing at red lights and the idle is irregular . I've been searching the threads and I think this Idle Air Control valve may be the problem . I just need to know what i'm looking for . His truck is a older model 2000? And im not really sure if its a 4.6 or 5.4 ? does this matter? Any help would be appreciated . Thank in advance !!

 

not sure on yours but its about 5-6 inches long and looks like a cylinder with 2 bolts, its right around the throttle body and should have a wire going into it.

 

should be on the back of the throttle body. JBrew will be on with pics i'm sure

 

look around the throttle body a cylinder with 2 bolt flange off the end of it like buzz was talking about. if you knew whether it was 4.6 or 5.4 we could pinpoint exactly. but then again, maybe our description of the location can help. it will be behind the TB too.

my 97 4.6 had it behind the TB on the driver side on top.

 

Thanks guys, I'll look at his truck tomorrow !!

 

A large vacuum leak will cause the same symptom.

Check the PCV elbow at the firewall side of the throttle body.

Steve

 

This is the IAC on my 5.4 (towards the back of the TB elbow, near the firewall)


Sorry no pic of the 4.6 that I can find, but it should be to the right of the TB if you are looking straight at it....where's jbrew.......

Oh and like Steve said above, while you are back there, check the PCV elbow. Follow the hose from the PCV valve on the left engine valve cover to the back of the TB elbow. It will be a 90 degree rubber elbow(its the big insulated hose underneath that runs to the rubber 90 right below the IAC), those tend to break down and cause vacuum leaks which will cause a rough idle.

 

I did find out it is a 4.6 . Thanks guys, This site and all members s

 

theres a 4.6, on the drivers side of the throttle body you can see the same thing jbrew's pic shows. mines just dirtier lol
between the EGR and the tb

 

Here , whats up ? The OP states a warm idle issue. First you have to see if there's a difference in the way she idles cold vs warm to eliminate a few possible problems.

The O2's influence warm idle among many other things. They don't however have anything to do with idle when cold. An IAC problem is usually more apparent at cold idle.

I'm thinking this is a combination of problems really. Leaks in the PCV system generally cause high idle issues, but in certain situations that doesn't alway apply. No need to go there yet.

It sounds like his PCV valve is plugged or close to it or that the EGR valve is WFO and stuck there. The Throttle body and elbow ports may also be dirty/carboned up. The MAF could be really dirty since he's getting surging/looping issues while warm..

Clean the MAF -

http://www.fordf150.net/howto/clean-...low-sensor.php

Clean the TB/Elbow as well/link = 4.6L iac local -

http://www.fordf150.net/howto/throttlebodyclean.php

A few things have to be gone thru and cleaned up and checked out in order to determine where the problem exists.

 

thanks jbrew

 

what would cause the IAC to make a loud buzzing noise during warm idle?


'99 expedition
5.4 4x4

 

It's dirty and removing the IAC muffler causes that as well.

 

replace the IAC and clean the TB while your at it and your rought idle problem will be gone. Its not the hose. Clean the TB real good. You'll be amazed.

 

If is a 4.6 the IAC should be right on top of the throtle body assemply two I believe 8 MM botls hold it down unfortunately I don't have a picture to send you. Is about 5 inches long round in shape and has an electrical connector attached to it, hope it helps.