delsol1994

I'm hoping I can get some help figuring out why I have a high idle. The truck is a 1994 F150 with 5.0L engine and manual transmission. I cleaned the throttle body and IAC. When I checked the codes, I got code 12. I have replaced the IAC. That did not help. If I unplug the IAC, the truck will idle at 500 rpm. I've tried to find vacuum leaks, but I haven't found any. Any help would be appreciated.

VickMacky

Did you leave the battery disconnected for 30 minutes after installing the new IAC?

delsol1994

Not for 30 min around 10 min. I will try 30 min. Thanks.

delsol1994

Wished that would have worked but no luck.

VickMacky

So you just cleaned the IAC or just replaced it? What kind of PCV valve are you using?

delsol1994

Cleaned and then replaced the iac. I checked for a vac leak around the pvc and its a ford motorcraft pvc that rattles.

Aktech

Probably better to test for leaks then look for them. Clean the Tb also.

delsol1994

I checked for leaks with Propane and then carb cleaner with no change in idle. I cleaned the TB with Throttle body cleaner and a clean cloth.

Aktech

Make sure the plates are closing all the way. And plug the egr with a coin to rule out a leak there. Measure engine vac.