High pitched humming sound.

[rikguy]

Forward me your email addy I'm I'll send you a pic.

 

[TPLYNCH]

Originally posted by 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?

It's on the drivers side of the throttle body, in plain view. You can't miss it.

 

[TxRanger351w]

My first post on this forum. But this also happens on the 4.0 Aerostars. My mom has a 97 and you can hear the god awful howl from 40 feet away. Glad I stumbled upon this thread. I'll try the breather cap first, and if that doesn't work, then we can get a new IAC no problem, and at dealer cost.

 

[gerry]

I think we are missing the point with the IAC noise.

The IAC valve opens/closes a port between the two chambers. It does not throttle the amount of air that comes through the filter that is making the noise. That little filter is just a vent for the electrical solenoid. The solenoid is connected to the valve by a shaft that is supposed to have a seal on it. This seal prevents the engine vacuum sucking through the solenoid housing. When the seal dies, you will get air passing through the "vent" filter, through the solenoid, and into the engine. The whistle is from air velocity in the solenoid "vent."

What I'm getting at is that the proper "quick fix" might be to block the hole rather than enlarging it (by removing the filter media). I'm not sure which port is which, but if the port on the solenoid end is the engine intake port (which I suspect it is due to the vacuum leak you are hearing) you are effectively bypassing the IAC by openning up the hole.

Hope this helps!

gerry

 

[j.costa]

I had this same problem with my 95 explorer. Humming noise resonating from the filter housing. Troubleshot it to the idle air valve. Replace it all good.