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?

 

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

 

It idles down and acts as if it wants to die. I believe i will replace the IAC

 

could be the throttle positioning sensor then
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

 

I'm having the same issue, but I don't think it's the IAC. Did you try to unplug it? Mine nearly died, I pulled it off but it was clean inside it.

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.

 

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.

 

agreed on the junk replacements
and cleaning is a temporary fix

 

any updates?

 

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.

 

That's like saying why wash your underwear they are just going to get dirty again. The new IAC is gonna get dirty, too. Cleaning the IAC is a periodic maintenance item, like replacing brake pads.

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.

 

I cleaned the IAC and noticed a considerable difference in the way the truck runs. I am still going to replace it when i get the money but cleaning it did help!

 

Did it just help, or did it fix the issue? I cannot see replacing the IAC if cleaning it alone solved your idling down issue.

 

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.

 

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.

 

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.