Hey guys
I have a '91 XLT with a 351 with an idle problem. It has 55k original miles on it and runs like a champ. It has been well cared for and is clean as a whistle. My issue is that when you first start it up and the engine is cold, it has a very fast idle at about 1500. Then after about 20 or 30 seconds, it slows down to near normal at about 800-900. After it warms up however, the idle goes back up a bit too fast at about 1200. Also every once in a while while driving, the "engine light" comes on but then goes off. I don't know if the two things are related.
I'm thinking the fast idle might be the IAC (idle air control) because if you disconnect the IAC, the idle comes down to about where it should be, but I don't know for sure. Does anyone have any idea what the issue could be? Can a IAC malfunction when it gets hot? Also what about a bad TPS (throttle position sensor) or bad EGR valve or EGR sensor? Can either of these cause my fast idle?
Thank you in advance for any help.
Sincerely,
Stuart D.
Portland, OR
I have a '91 XLT with a 351 with an idle problem. It has 55k original miles on it and runs like a champ. It has been well cared for and is clean as a whistle. My issue is that when you first start it up and the engine is cold, it has a very fast idle at about 1500. Then after about 20 or 30 seconds, it slows down to near normal at about 800-900. After it warms up however, the idle goes back up a bit too fast at about 1200. Also every once in a while while driving, the "engine light" comes on but then goes off. I don't know if the two things are related.
I'm thinking the fast idle might be the IAC (idle air control) because if you disconnect the IAC, the idle comes down to about where it should be, but I don't know for sure. Does anyone have any idea what the issue could be? Can a IAC malfunction when it gets hot? Also what about a bad TPS (throttle position sensor) or bad EGR valve or EGR sensor? Can either of these cause my fast idle?
Thank you in advance for any help.
Sincerely,
Stuart D.
Portland, OR