Idle Air Controller?
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Freshman User
Joined: Nov 2011
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From: Sugar Hill, GA
Idle Air Controller?
I have a 2002 F-250 4x4 5.4 liter.
Just recently it started making a high pitched hum, maybe you could call it a whine, at idle and even with a little bit of throttle. The noise is most noticeable until the engine is warm. I can't hear it at all if I've got more than the slightest bit of throttle engaged. It seems better, but not quite gone, at idle after the engine is warm.
Poking around the site a little it seems possible that this is the IAC. How can I confirm that? Where is this creature located? Any other useful bits of info will be appreciated.
Thanks,
Matt
Just recently it started making a high pitched hum, maybe you could call it a whine, at idle and even with a little bit of throttle. The noise is most noticeable until the engine is warm. I can't hear it at all if I've got more than the slightest bit of throttle engaged. It seems better, but not quite gone, at idle after the engine is warm.
Poking around the site a little it seems possible that this is the IAC. How can I confirm that? Where is this creature located? Any other useful bits of info will be appreciated.
Thanks,
Matt
Fleet Owner
Joined: Aug 2010
Posts: 21,253
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From: Reynoldsburg, Ohio
Could your noise be the alternator whining or perhaps a vacuum leak?
The IAC will greatly affect the engine idle to the point it stalls unless throttle is applied. I've had two different E250's with problem IAC's and neither had this hum or whine you mention.
The IAC will greatly affect the engine idle to the point it stalls unless throttle is applied. I've had two different E250's with problem IAC's and neither had this hum or whine you mention.
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Freshman User
Joined: Nov 2011
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From: Sugar Hill, GA
I wouldn't think a vacuum leak or an alternator would stop making noise on increased throttle or when the engine is warm, but clearly I don't know what the noise is. I'll see if I can narrow it down today.
Thanks for the reply.
Thanks for the reply.
Fleet Owner
Joined: Aug 2010
Posts: 21,253
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From: Reynoldsburg, Ohio
Yeah noises like this can be aggravating so maybe crawling around under the hood just after starting up first thing will help locate the actual source.
I had a similar noise that turned out to be the throttle body air ducting that runs off the air cleaner housing. Interestingly enough this was due a long term bad PCV allowing oil to pool inside and softening it to the point it leaked--seemed to happen more during cold weather start ups, occasionally throwing "lean bank 1, lean bank 2" codes.
I had a similar noise that turned out to be the throttle body air ducting that runs off the air cleaner housing. Interestingly enough this was due a long term bad PCV allowing oil to pool inside and softening it to the point it leaked--seemed to happen more during cold weather start ups, occasionally throwing "lean bank 1, lean bank 2" codes.
Postmaster
Joined: Nov 2006
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From: SE Wyoming
Need to pull the belt off next time it is cold and see if the sound goes away, that'll either eliminate or prove it is a belt driven problem. Power steering for instance makes horrible noises when really cold.
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Freshman User
Joined: Nov 2011
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From: Sugar Hill, GA
Well, it seems like it might actually be the alternator. It was making the noise this morning. I put one end of a broomstick on various parts with the other end pressed against my ear. The noise was much more pronounced when I was listening to the alternator.
Does this mean something bad for the alternator, or is it just going to make that noise when it's cold?
Does this mean something bad for the alternator, or is it just going to make that noise when it's cold?
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Fleet Owner
Joined: Aug 2010
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From: Reynoldsburg, Ohio
That sort of noise at any time suggests a bearing could be going bad---------how long is has left is anybody's guess.
Not sure how many miles on your alternator but I'd pay closer attention to that sound and the voltage gauge on the dash. If the budget and time allows maybe have it checked out and rebuilt unless a new one is close in price.
Glad that's all it was!
Not sure how many miles on your alternator but I'd pay closer attention to that sound and the voltage gauge on the dash. If the budget and time allows maybe have it checked out and rebuilt unless a new one is close in price.
Glad that's all it was!
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take the belt off and check the alternator shaft for play. also spin it by hand and feel for anything besides normal smooth operation. as mentioned before, i would take the belt off and start the engine cold when it is making the noise and help narrow the possibilities.
i dont generally accept the old prybar/microphone diagnostics, they are usually wrong and there are better more certain ways of diagnosing a problem.
i dont generally accept the old prybar/microphone diagnostics, they are usually wrong and there are better more certain ways of diagnosing a problem.
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