High pitched humming sound.

[Texplorer]

Robert- Yeah I know, I even took the guy out to the X popped the hood and pointed at it and he said that it was the throttle body . He then said that my DPFE was a solenoid. So I smiled and walked away.

 

[DasFrem]

Ok guys, you might all like this, so I was looking at this thread:
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and jwrezz said that when he removed that black knob thinggy (my new tech term for it) he said the hum went away. So I ran out and tried and and Viola! no hum! and the idle is fine. what it is, is a breather cap and there's a little filter in it to let in air. What I suppose is going on with most of us is that when we put on our FIPKs, the motor can breath easier right? Well then the IAC needs to breath better (I could be wrong, but it makes sense to me). So what I'm doing is drill a few small holes on the inside of the cap to let it breath easier. You have to pull yours off in order for this to make sense, it's kinda hard to describe what it lookes like on the inside. so heres a pic of what I'm talking about and when I'm done, I'll tell ya'll if it works or not.
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[Robert]

My hum doesn't have anything to do with my FIPK since my FIPK had been on for two years prior to the hum. My hum started when I hosed off my motor.

 

[DasFrem]

Well then, the water could have clogged the breather cap.

So I took that breather cap, drilled all kinds of holes in it and the hum got much quieter. Then I went too far and cut some of the bottom of the breather cap off to make it shorter (I don't really know why, I thought it might help) and kind of ended up destroying the cap. So anyway, I just have it totally removed for now unitl I can think up of another solution. On the bright side, it makes abosoulty no hum.

 

[Jason_25]

Dasfrem, did it make the idle any better? Or was yours idling fine while it was humming?

 

[RedBeard]

DasFrem,

I paid $70 at Towne Ford in Orchard Park NY. When I first asked for an IAC for my '96, he said there was two different IACs available... the only difference was that the electrical plug was 45 degrees offset. I ran back out to my truck, looked, and picked the right one. If I needed the other IAC, it would have been $92. The parts guy said that the ONLY difference was the position of the plug (and the price). Before I went there, I called two other Ford dealers... got prices ranging from $90 - $140 for an IAC. Your VIN will narrow it down for them.

As for the breather cap thingy, I pulled mine off of the old IAC, cleaned the little filters but it didn't do much good... hum returned a day later.

I think that the mechanism inside gets dirty and the solenoid does not actuate fully from open to close. If it doesn't close all the way, or open all the way, it allows just enough air in to make it hum.

-RB

 

[DasFrem]

The idle seemed slightly heathier, but it could be my imagination, I was just happy the hum was gone.

 

[psychotic]

OK guys, if you have a loud hum at idle AND mid-full throttle, you have a totally different problem, maybe its your fuel pump. If it is only at idle, it is most likely the IAC valve. As the IAC valve gets older, the spring in it wears out, causing the valve not to open all the way. So when you idle, and your throttle plate is closed, the only way air can get in your engine is through this valve. This is how it helps control your idle, but since it is worn and does not open all the way, it acts like a very loud whistle. This whistling sound WILL resonate down the air intake and make you believe it is an intake problem. The reason people notice it more after a K&N FIPK or other similar intake is because there is now no airbox to help deaden the sound, and also the "whistle" is allowed much more air to hum louder. Hope this helps! You can try taking off that cap like some people on this post have done, it might free some air flow and cut out the whistling. A for sure solution would be to replace the IAC valve. I've heard it isn't hard and i plan on doing it sometime here soon.

 

[aqs789]

I just dropped in a K&N FIPK and noticed a high pitched humming noise coming from the filter when I'm at idle. After reading this thread I think it may be the IAC. I never changed my IAC valve, but I only have 53,000. Aother thing is when I'm on the highway (about 55mph) and I hit the gas I hear an air noise like someone is blowing. It comes from the front passenger side. Is this normal with the FIPK? You people with the IAC problem, how is your idle? Is it steady, or does it fluctuate? Thanks

 

[Lemondrop]

This is my reply in the "e-mail about MAF" sticky thread . I cut and pasted it here
Seems everyone is getting beat up over this IAC filter , it likes to makes noise when it is hot outside .



It's not the air filter housing

I thought mine was doing the same thing and I tore the thing apart and checked everything . Nothing was wrong so I assumed the screen was loose and rattling . I bent the screen a little to put a bow in it so it wouldnt rattle . Still made the loud humming noise .
Someone said it might be the air filter on the Idle Air Control motor (on the side of your throttle body *looks like a beer can mounted sideways) ..It has a little black plastic cap and the cap is the air filter . When it becomes plugged for some reason the entire mess starts humming at idle . Mine got even worse once it idled for a few minutes and the engine compartment got real hot .
Pull the black cap real hard and it will pop off . You will think you busted it but it's the glue they attach it with breaking loose . Once you get it off , spray brake cleaner (or anything that won't damage plastic real easy) into the CENTER of the cap . You will need the little red extension that come with the can of brake cleaner to be able to spray down in it . You will see the dirt flow out of the outer edges of the filter . Continue flushing till the dirt runs clear . If you can blow air through the hole once it's clean it will speed up drying out the cleaner . If not let it dry a second then put it back on the IAC motor , just shove it back on . Fire the engine and let it idle ..... the hum will be gone . Of course you could replace the IAC itself .. mine was replaced and 10 months later it was making noise .
Ive thought about making a new filter out of tubing and a fuel filter (paper type) but never got around to it .

 

[rikguy]

iac - filter?

Do you need that filter under the cap? I pulled mine out 3 days ago and the noise is gone. Will anything that could cause damage get thru without replacing the filter? I thought about maybe using paper coffee filters, several layers thick to replace the old filter. Thoughts?

 

[Lifted95X]

I replaced mine with some fabric very similar to what was in there....and the noise came back within days.

 

[rikguy]

it seems to me that the part isn't the problem but the filter is. It doesn't let enough air flow thru. If you replace the part, wouldn't the new filter get dirty and start the noise again?

 

[Jason_25]

Messing with that filter won't help any. The plunger itself gets worn and allows a small amount of air to slip by, thus the sound.

 

[psychotic]

congrats rikguy, you found the same solution i did, i took out that stupid filter and no hum. I too was afraid of stuff getting in, so i put a few layers of coffee fliters, but they started to rip up, so i didn't want that going in my engine, i've had it running about a month with no filter in the iac, and so far so good, i hope nothing can get through there that would damage anything

 

[sapogmxr]

Wow this is an old post. No need on starting a new one though. I have the same problem. My noise is Really loud! I can hear mine from about 40ft away! For those who took the cap off how has that been working for you? Has the noise returned through time?

 

[DasFrem]

Noise never came back for me

 

[psychotic]

When i took out the filter in the IAC, I had no noise come back... it seems the filter is what was making mine whistle. I got a new IAC valve to try and help rough idle later though.

 

[rikguy]

my noise has not come back, but ..... I am having rough idle problems and a CEL. I'm going to replace the IAC (as soon as I get an xtra $94 + shipping).

 

[sapogmxr]

Thanks guys. I guess im gonna try and clean the cap/filter. Does anyone have a picture of were it is on a 4.0 ohv?