I have a 91 Caravan, 2.5L The idle is all over the place, but I wouldn't say it is a rough idle. It will accelerate to high rpm's on it's own and sometimes come back down to a normal idle. Other times, it will just idle high, then low, then really high and then back to normal. It never misses or runs rough, just idles high and low, but never low enough to kill the engine.

I'm not sure what this would definitely be, but I didn't want to start replacing sensors and have it not be the case.

I've checked for vacuum leaks, timing, spark plugs, plug wires, distributor, rotor, etc. Over 2 years ago I had replaced the IAC and the TPS sensors. I know for a while this thing was running very rich so I ended up changing the O2 sensors as well.

Does this sound more like the IAC? What do you all think?

Any suggestions would be fantastic!!

Thanks a bunch,

Pat Rogers

 

Try cleanning the throttle body and the AIS motor too. Then ck for vacuum leaks. 2.5 motors were bad for cracked vacuum lines.

 

Thanks for your reply, I really appreciate it!

The AIS motor, is this different than the IAC? I'm assuming it is and haven't really looked under the hood or checked the manual for it. Could you tell me where the AIS motor is typically located?

Thanks again,

Pat Rogers

 

Its the same part, the dealer calls it an ais motor and ford dealer calls it iac motor. But it the same thing, adjust idle.

 

Ok great! Thanks for the helpful advice!!!

Pat Rogers