I have a '97 with 5.4 motor. I am having rough idle problems and I here guys talking about cleaning and replacing the IAC valve. What is it and where is it on the 5.4? How much will it cost new???

 

just put a new one on my 97' it cost $45 at o'reilly auto parts

 

where's it at? What's it do?

 

It is a cylinder mounted to the throttle boby with a wiring harness plug attached. I is basically a computer controlled valve that bypasses air around the throttle plate( butterfly). By doing this the computer can control the idle speed. Rough idle can sometimes be caused by this valve getting debris in it and causing it the stick. the computer cannot control the idle as precisely and thus you get a rough idle. several other things can cause the same symptoms but if you are looking for the IAC it is on the throttle body in the area of the throttle plate

 

Ok, the iac is between the intake and the throttle body. If you follow the path of the intake directly to the TB youll see there are two points where it branches on the right side. The upper one goes to the IAC, its a small cylindrical metal piece about 1 inch in diatmeter and 2 inches long. Replace is best but you can clean the inside with carb cleaner and hope it helps. Its held in with a connceter and 2 7or 8? mm bolts.


Edit: rats pestco beat me to it , in anycase yeah he describe it right, although one thing to note, its not the culprit of rough idle most of the time, normally thats a vacuum leak (i would check the pcv and the tube connected to it all the way to the back of the throttle body), more often it causes stalls at stops and a fluctuating idle rpm.

 

thanks guys