Replace the IAC?
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Freshman User
Joined: May 2006
Posts: 27
Likes: 0
From: Clarksville,TN
Replace the IAC?
86 F150 302 FI AOD trans
When cold, truck starts and runs at high idle for about 3 or 4 minutes. Then idles down and dies. Restart and will idle high for another 3 or 4 minutes and idles down and runs fine. Reving the motor will not drop the idle. Starts and runs normally when warm.
I've had the throttle body,iac and tps off and throughly cleaned with carb cleaner. New fuel pumps, fuel filter,air filter,PVC,wires and have run several forms of fuel cleaner and drier through the system. Timing is at 10 deg. with spout unplugged. Just wondering if I need to maybe replace the IAC to solve this idle problem. Thanks.
When cold, truck starts and runs at high idle for about 3 or 4 minutes. Then idles down and dies. Restart and will idle high for another 3 or 4 minutes and idles down and runs fine. Reving the motor will not drop the idle. Starts and runs normally when warm.
I've had the throttle body,iac and tps off and throughly cleaned with carb cleaner. New fuel pumps, fuel filter,air filter,PVC,wires and have run several forms of fuel cleaner and drier through the system. Timing is at 10 deg. with spout unplugged. Just wondering if I need to maybe replace the IAC to solve this idle problem. Thanks.
Fleet Owner
Joined: Aug 2005
Posts: 23,666
Likes: 301
From: Easton,Ks
Originally Posted by subford
Sounds like normal operation to me.
No it should not die but that is a whole other question and could be a lot of things.
Posting Guru
Joined: Nov 2004
Posts: 2,155
Likes: 1
From: sunny fla sometimes windy
What is the idle with the IAC unplugged? You should have around 500 rpm adjust the
hard throttle stop to get that, reconnect IAC. I hope you held the solenoid deal up while cleaning the IAC or you may have gunked it up!! I use Chemtool b12 carb cleaner
nothing else seems to clean it as good. Put a multimeter on the temp sensor and see if it looses contact or goes flat while truck is warming up.
hard throttle stop to get that, reconnect IAC. I hope you held the solenoid deal up while cleaning the IAC or you may have gunked it up!! I use Chemtool b12 carb cleaner
nothing else seems to clean it as good. Put a multimeter on the temp sensor and see if it looses contact or goes flat while truck is warming up.
Moderator
Joined: Dec 2001
Posts: 22,436
Likes: 17
From: Louisville,Ky.
I would replace the IAC, it sounds like it is sticking and is sluggish so when it idles down, it doesn't reopen fast enough to keep from choking out the engine. Pretty common on older units.
Lead Driver
Joined: Jul 2007
Posts: 7,868
Likes: 9
From: Rhode Island
Same thing is happening on my ranger. It got stuck in a high idle, I whacked the IAC with a wrench, and it went back down
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Posting Guru
Joined: Nov 2004
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From: sunny fla sometimes windy
Don't waste the money just spray it out and for a $4.00 carb cleaner and a $3.00 tube
of rtv it will be fixed for quite awhile The rtv will probably harden before you have to
do it again!!
of rtv it will be fixed for quite awhile The rtv will probably harden before you have to
do it again!!
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Thread Starter
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Freshman User
Joined: May 2006
Posts: 27
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From: Clarksville,TN
Temp sensor checked out ok. Cleaned the IAC again the other day. No go. Oh well, never hurts to try and save a little coin. Replaced it and the "Pig" now idles fine with no dying after cold start. Thanks for the replies.
Lead Driver
Joined: Jul 2007
Posts: 7,868
Likes: 9
From: Rhode Island
Originally Posted by blue beast
Don't waste the money just spray it out and for a $4.00 carb cleaner and a $3.00 tube
of rtv it will be fixed for quite awhile The rtv will probably harden before you have to
do it again!!
of rtv it will be fixed for quite awhile The rtv will probably harden before you have to
do it again!!
Posting Guru
Joined: Nov 2004
Posts: 2,155
Likes: 1
From: sunny fla sometimes windy
The reason the motors go bad is because people tell others to clean them without
removing the solenoid deal or holding it up so the dirty carb cleaner doesn't run into
it!! It is only two screws on most and others just hold them up and Do NOT reconnect
without it being completely dry!! Or it is instant toast.
removing the solenoid deal or holding it up so the dirty carb cleaner doesn't run into
it!! It is only two screws on most and others just hold them up and Do NOT reconnect
without it being completely dry!! Or it is instant toast.
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