Mysterious underhood noise...

[dlphnfn]

I looked in the under hood noise thread and I couldn't find anything that matched my Xs noise. It sounds like a howling cat! It changes frequency and volume based on RPMs mostly. It doesn't do it all the time, just on slow accelerations (in gear or not).

It might be the cam position sensor, but I'm not not sure the SOHC 4.0 has a mechanical one (looks like a module of some sort when I look up the part).
Any help?
Erick --

 

[albi1cnobi1]

It could be the IAC valve. They've been known to howl.

 

[dlphnfn]

I googled a couple IAC howling issues and the howl seem REALLY bad right in the air breather. It might be worth me taking that off tonight to see if it is really loud inside there. Thanks for the heads up. It does seem more like a howl and this sounds more like a screech.
Erick --

 

[Flash]

Try cleaning the IAC valve first, if it's not that then look at the alternator bearings, AC pump and power steering.

 

[Turdle]

Take out the air filter, shake it and blow it out with some air, then rotate it 180 degrees in the housing and try again. A new air filter may even get rid of the vibration.

Cleaning the IAC can and often does cure this also. Pay close attention to the plunger and seal area, my theory is the seal vibrates like a reed in a clarinet. Or could it be an oboe?