Lately my F150 has developed an issue with cold starting when the temperature is near freezing or colder. It won't idle properly. It will run with the pedal slightly pushed, but otherwise it fluctuates from about 500 to 1500 rpm and nearly stalls. It is an MAF truck. The IAC is new. I'm thinking it could be the intake air temp sensor. There are no current trouble codes.

 

My 94 starts rough but once it goes it runs good. I attribute it to a combination of winter fuel and the timing advance I set. I also suspect the ICM but haven't messed with it.

 

I haven't solved this yet. I'm beginning to think that it could be a vacuum leak causing this.

 

A rolling idle is typically caused by a sticking IAC, poor quality IAC, faulty TPS, vacuum leak.

 

What brand IAC do you have? Those Chinese IACs you get at Autozone and the like are junk in my experience.

 

anyone had any experiance from a napa IAC?

 

I have a BWD brand IAC. I would have thought it'd be decent, but maybe not.

 

Run the KOEO tests and CM code display before throwing money at the problem.

 

Note a stuck open purge solenoid can cause this also.

 

Its looking like the nearly new IAC was sticking. This morning it would barely idle and nearly stalled several times. After tapping on the IAC with a hammer and a screwdriver, it smoothed out. I just wouldn't have guessed that it was bad. Hoping it is back to normal now.

 

You should invest in a Motorcraft IAC, IMO.

 

I think using OEM is the best way to go too! Most everything at the parts stor comes from China.

 

I agree that is a better idea. I may get a Motorcraft one. At least it has one that works better now.

 

Can't find my receipt.

 

I would not have guessed that the Motorcraft unit was made in Japan.