"Excessively high idle"
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New User
Joined: May 2004
Posts: 5
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"Excessively high idle"
I have a 1989 Fullsize 302 that idles around 2000 in neutral. Installed a new IAC valve, to no avail, and everything else checks out O.K. Any suggestions would be greatly appreciated. Thank You
Tuned
Joined: Oct 2002
Posts: 466
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From: South Central KENTUCKY
Just went through this with mine, same thing. Take the IAC off and duct tape over the opening on the intake. Start it and see what it does. Mine I had put a bad iac on it. also check out http://fordfuelinjection.com run a self test and see what comes up.
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New User
Joined: May 2004
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"Attempt at correcting high idle"
Changed TPS today with no success. I still get 2000rpm's in neutral. Timing can't be advanced as there is no detonation. So far its IAC and TPS. Can I pick your brain one more time? Thanks for the assistance.
Elder User
Joined: Oct 2002
Posts: 573
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From: Medina, Tn.
If you have already guaranteed you have no vacuum leak and have replaced your IAC and TPS, adjust the stop screw or whatever it's called and bring it down that way. Many will tell you to never do it but I did it about 3 years ago and am still getting over 15 MPG and runs like a top. Not bad for a vehicle with over a quarter million miles on it. Dang, that sounds like a lot. You will see what I am talking about if you take the black plastic cover off the top of the throttle linkage etc... Warm it up a couple of minutes where it is settled down to its' curb idle and then start bringing it down until you get to about 650 - 700 RPM's. If things don't work out, you can always adjust it back up.
Let us know what you end up doing.
Good luck,
Let us know what you end up doing.
Good luck,
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Senior User
Joined: Apr 2004
Posts: 443
Likes: 1
From: Central Va.
High Idle
Replace upper plenum gasket. Gasket between upper intake and lower intake manifold sucked in creating massive vacuum leak.Sometimes pcv valves come apart(plastic) but still replace with correct ford part or you may end up with new problem!!!
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New User
Joined: May 2004
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"Problem solved"
Turned out it was the upper plenum gasket. The old tried and true aerosol brake cleaner found the culprit. Idles at 700 rpm's. Seems strange to drive it now. Before with both feet on the dash I could make 38mph. Thanks for all the help folks. If I can ever return the favor let me know. I restore yachts for a living and have painted for 32 years. Never know, maybe someday I can be of assistance. Thanks Again
Senior User
Joined: Apr 2004
Posts: 443
Likes: 1
From: Central Va.
high idle
Glad you found your problem. Hope you didn't turn your idle stop first.I have worked at the same Ford service dept. since Aug. 1977 and we see a lot of problems when the idle stop is changed,always clean throttle body before attempting idle concerns repairs. Sticking accel. pedel requires turning stop slightly. REMEBER CLEANING THROTTLE BODY IS THE CHEAPEST REPAIR YOU WILL EVER DO WITH THE GREATEST AMOUNT OF RESULTS AND SATISFACTION!!!!!!!