My 90 Bronco,302, AOD idles at 1200rpm +. I've replaced the MAP sensor, TPS sensor, Idle Air Control Valve. The computer codes are all 1's. The truck started running a little rough when this idle problem started. I'm thinking the computer is bad. Any ideas anyone. I'd appreciate any help I can get.
Burning up brakes in Texas.
Gerald

 

Gerald, before you change computer, try cleaning out throttle body (specifically around the butterfly and edge of butterfly). Carbon buildup in this area sometimes causes a poor idle. Also, disconnect battery for about 20 minutes, and leave a door open. This resets the computer. Good luck. Don


"Nothing lasts forever except natural stone and old Ford trucks." (Willie Nelson)

 

Don,
I cleaned the throttle body and butterflies. I also reset the computer. Unfortunately nothing changed. Thanks for the info and guidance. It's greatly appreciated.
Gerald

 

could be a vacuum leak..esp at the throttle body.
are you thinking the codes are for "system ok"?

 

Thanks AIM,

I did another extensive check of the induction system and found a leak in the lower plenum.

Thanks again,
Gerald

 

Also, look at your little Idle "motor" it's on the right side of the throttlebody, and has a solenoid attached to it, if you unplug the solenoid, i bet your idle goes down, you may have to clean/replace it, mine went bad, so I just left mine unplugged and brought the idle to the right speed using the little set-screw just like you would a Carb, works great now, my "idle motor" was getting really jacked up, it must have been wide open for a while and it started all the sudden my bronco would (after taking it OUT of gear) would go all the way up to 2K Rpm, i unplugged the solenoid, and bam, right where it needs to be.

P.s. I removed mine and cleaned it out, it had ZERO effect

C

 

Thanks for the info C. I did try unplugging the solenoid before, and the idle did not change. I was thinking the same as you. I did discover a leak at the manifold. Working on it now. Thanks again and I'll keep the idle solenoid in mind for future reference.
Gerald