IAC valve
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New User
Joined: Sep 2011
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From: St. Clair, MO
IAC valve
I posted a thread about my 1988 Ford F-150 with a 302 Automatic that had an idle issue..... I have done some research and believe that my culprit could be my IAC, but I have not taken it off and cleaned it yet or replaced it. Anyone ever had to do this?
Fleet Owner
Joined: Jan 2008
Posts: 26,898
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From: southern md
are you having a high idle issue?
if so remove the large air intake hoses from the assembly
and look to the right side "small hole"
truck running plug it with finger
if it idles down --replace IAC
cleaning seldom helps
if so remove the large air intake hoses from the assembly
and look to the right side "small hole"
truck running plug it with finger
if it idles down --replace IAC
cleaning seldom helps
Fleet Owner
Joined: Jan 2008
Posts: 26,898
Likes: 3
From: southern md
you might want to try cleaning the air intake assembly
be sure to use the correct spray though
they have a coating on em and regular carb cleaner eats it off
Laughing Gas
Joined: Aug 2006
Posts: 815
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From: mountaintop, Pa
Fuel Injection Technical Library » Idle Air Bypass (IAB)
It's driving me crazy, I did replace the TPS also but I was getting an error code for that.
Let us know if it works, maybe it is my AIC.
Lead Driver
Joined: Feb 2002
Posts: 7,970
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From: Greater Austin, Texas
cleaning seldom helps
If you are gonna replace it, be sure to use a Motorcraft replacement. The ones they sell at Advance, Autozone, et al, are junk.
Fleet Owner
Joined: Jan 2008
Posts: 26,898
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From: southern md
This has not been my experience at all. Cleaning *always* helps. It's not permanent, you have to clean them periodically. This is very common on Fords. I have never replaced an IAC valve in almost 1MM miles of driving IAC-equipped Fords.
If you are gonna replace it, be sure to use a Motorcraft replacement. The ones they sell at Advance, Autozone, et al, are junk.
If you are gonna replace it, be sure to use a Motorcraft replacement. The ones they sell at Advance, Autozone, et al, are junk.
and cleaning is a temporary fix
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Laughing Gas
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From: St. Clair, MO
I havent had the chance to replace it or clean it yet guys, but I will be sure to let everyone know when I do. The reason I think its the IAC is because I did some research and I was told that If I took the IAC off the motor and took it apart and turned the key on with it still plugged in that the plunger would move in and out but it wouldnt move. They said that if doesnt move that the IAC was junk.
Lead Driver
Joined: Feb 2002
Posts: 7,970
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From: Greater Austin, Texas
and cleaning is a temporary fix
Having said that, it's important to use a cleaner that is throttle-body safe, since the IAC, like the TB, has a coating that prevents buildup of deposits. If your cleaner strips that away, then it's going to get dirty faster.
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New User
Joined: Sep 2011
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From: St. Clair, MO
It helped with the Issue, it didnt fix it. It idled really rough and low, but then I cleaned it and it actually wanted to run on its own but it was still rough. Its the original IAC from 1988 so its probably junk.
Lead Driver
Joined: Feb 2002
Posts: 7,970
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From: Greater Austin, Texas
When you clean the IAC, you must disconnect the battery for at least 10 minutes to reset the ECU. It will then relearn your driving style and adjust the idle accordingly. This can take up to a week for the computer to dial it in just right. I don't know why, but it seemed to take much longer for my Windsor motors to settle in on how they wanted to idle than it did for my 300 Six and current 460.
Cargo Master
Joined: Nov 2003
Posts: 2,585
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From: Duluth, Mn.
I'd bet You have 2 problems, neither involves the IAC. More than likely You have a vacuum leak, possibly the vacuum reservior. I'd almost bet Your EGR is not fully closing. Prolly caked with carbon deposits.