2.9 Won't idle down
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Senior User
Joined: Feb 2003
Posts: 192
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From: Puyallup, Wa.
2.9 Won't idle down
Hi, great site. First time posting. I have an '88 Ranger XLT bought new in '88. 2.9, EFI. 4WD, 5 Spd. Got 295,000 miles on it. Regular maintenance performed. After truck has been run for a while, when I push in the clutch, the engine won't return to idle immediately. After freeway driving, it remains at about 2000 rpm, street driving about 1500 rpm. It eventually idles down, any where from 10 to 20 seconds. After freeway driving doesn't return to normal idle, about 1200 rpm. This all happens about 50% of the time. Nothing has ever been done to the emission system.
Post Fiend
Joined: Dec 2001
Posts: 10,562
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From: South Jersey
2.9 Won't idle down
Welcome to Ford Truck Enthusiast!
The IAC controls the idle speed and can get dirty and stick, you could try cleaning this or replacing it since it's original. The IAC is the thing on the upper intake on the passengers side, looks like a film canister with a tail and two wires. Just an FYI in case you don't know, the 2.9Ls are known for cracking heads so never let it overheat.
The IAC controls the idle speed and can get dirty and stick, you could try cleaning this or replacing it since it's original. The IAC is the thing on the upper intake on the passengers side, looks like a film canister with a tail and two wires. Just an FYI in case you don't know, the 2.9Ls are known for cracking heads so never let it overheat.
Tuned
Joined: Feb 2003
Posts: 355
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From: Oregon
2.9 Won't idle down
My '86 2.9 used to do that after coming off the freeway. I'd shut it off, wait for a few secs, re-start and it was fine. It didn't do it very often, but I replaced the IAC about a year ago and it hasn't done it since.
Senior User
Joined: Oct 2002
Posts: 420
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From: Harrisburg USA
2.9 Won't idle down
That many years & miles ... THAT'S GREAT! After that many years & miles, it doesn't "hurt" as much to accidentally replace something that wasn't malfunctioning yet, in the struggle to fix an illusive problem (my own personal perspective). In case the IAC doesn't seem to be the culprit, check out the TPS, & all connections to & fro (clean?? broken?? corroded?? etc).
Freshman User
Joined: Mar 2003
Posts: 46
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2.9 Won't idle down
Do 2.3L's have the same problem? I just finished clearing all the computer codes from my 2.3L with a final replacement of the HEGO sensor and I reset the computer to start fresh and that's when my problem surfaced. It's been a week and my idle doesn't go as high as kmans777 and EVENTUALLY drops to normal, but very, very slowly.
Senior User
Joined: Oct 2002
Posts: 420
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From: Harrisburg USA
2.9 Won't idle down
I don't know which engines had the IAC, but, as far as I know, they ALL have TPS (since about '81 or there abouts). Any of these engines could act that way (carb & FI alike) if the TPS is dirty, or failed.
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