cant on 4.6 its all in the tune...

sound like you need a new IAC

 

whats an IAC... what does it do?

 

Idle Air Control... its on the front of your plenum...

 

IDLE AIR CONTROL VALVE (IAC)

 

whats a plenum? wait, so i need a dyno to adjust this thing? or can i just run the car and adjust it myself

 

the thing that sits on top of your intake where the Throttle Body bolts to. You have a vaccum line and an electrical plug in on the front of the IAC. its two 8 mm bolts to take out and its 56.98 at advanced autoparts...

 

56.98 to replace it or tune it? Is that that black cap that you can remove and underneath is an allen wrench screw thinger?

 

Someone get this guy a picture!!! I'm not at my car right now...

 

This is what you need to change.

 

Thank you sir!

 

yeah yeah yeah, i know what part it is now, but do I replace that whole unit or do i tune it with an allen wrench?

 

It needs replaced. You can change the speed. These IAC's are a big issue with mustangs. They stick and mess with your idle. You can clean them with some carb cleaner so it doesn't stick. If that doesn't work then you'll need to replace it or your car with idle/die after start up.

 

THANK YOU! When you say "clean them" you mean unbolt it from the throttle body and ill see some kind of mechanism inside that seems to be sticking that i can clean.... right?

 

It's almost like a tiny piston in a sense. And I meant to type "can't" in the post when I was telling you to clean it. You cannot change the speed. (just to clear that up)

 

yeah take it off, and spray the hell out of it with some carb cleaner or intake cleaner. I cleaned mine twice, and it really made a difference in the way it idled. If it doesn't fix it, then you will need to replace it. I can't see the h pipe making your car idle much differently.

 

You can try backing out the set screw on your throttle body. Especially if you've messed with it, or put an aftermarket TB on. If not, the IAC is a good bet. The actual idle is set in the tune and only idles high if there is an air leak at the TB, a vacuum leak, or the IAC is messed up.

 

excellent information... thank you! However, im afraid that if i back out the set screw, that at first it will make my car idle right, but see after a certain amount of time the car will actually idle the way its supposed to on its own around 600 rpm... so you see, making any of my own adjustments to the screw to make it initially idle lower would make it stall if it tried to idle at 600 by itself.... you know what im sayin? Im guessing its the IAC that needs a cleaning, but if its not that then ill test for vacuum leaks and if its not that ill buy a new IAC.... maybe ill turn the screw a little bit....idk

 

I would bet it needs cleaned and if cleaning it doesn't help then probably a new IAC would be the next step.

 

I agree. just clean the IAC and see what the hell happens

 

i just cleaned the IAC with carb cleaner and a toothbrush... theres a little difference but it still idles at 2000 when i start the car up and it stays at 1500-2000 for atleast 10 minutes.... wheres the set screw that can be adjusted?

 

Its on the throttle body. It is the screw that keeps it from closing farther.

 

Did adjusting the screw help it at all?