idles high on start up and a farting noise when its shut off

got a problem with the gf sc when i start it up the rpm will go up to 2000 stay there for about 10 secconds then the idle will come back down. when you shut it off you hear kind of like a farting noise coming from the intake. does it sound like the bypass valve is bad?

Your Idle air control motor is bad. Go down and buy a Ford one just like the original.

I agree. I checked the other day on a IAC on a 3.8 N/A and it was the same part # as the SC IAC.

does it HAVE to be a ford brand IAC ? i bought one from advance auto (GP sorenson) and am still having high idle issues. it got rid of the "goose honk" tho.

well everybody says it must be a ford oem part or it dont work right i have no clue just somthing i have read up on.

I bought one from Auto Zone a few years ago and it wasn't even close to fitting. I think it was for a 5.0 but I made sure it was looked up as an SC. Heck I worked there.

I bought one from ford put it on and the goose honk noise went away, and my high (3000 rpm and glowing red headers from being too lean) went away.

If you have a bad IAC your car is gonna idle high and run lean. Reason is the TPS is showing only idle voltage meaning the throttle blade is closed. The IAC is allowing more air than normal into the engine causing it to rev up. The TPS says the throttle is closed so the computer won't add more fuel because it thinks the car is idling and only supplies enough fuel for idle. More air with less fuel equals lean condition.

Mine would get red hot headers in less then 3 minutes from a cold start and the temp gauge would go red hot. This happened right after my head gasket job and I was scared it was gonna pop the head gaskets again by running that hot and lean. So becareful and fix it asap. It was like $94.99 at Ford last time I bought one around here.

well, i dont mean to hijack the thread but i pulled codes and what related to this problem is 91 and 41 which says O2 sensors reading lean, will not switch and 81 which is IAC circuit failure. i swapped the iac with a non-ford part.

if i buy ford brand, think i will take care of it ??

fixed it

thanks for the replys i went out to the garage and changed the throttle body and the problem went away.

the throttle body ???!!! that got rid of it ? wow

the idle air control is on the throttle body i had one laying around that i knew came off a running car so i just threw that one on

oh, well good fix then. good luck with it.