Whistling/whining noise following engine speed

[dmention7]

So I've read the threads about exhaust mani cracks, charge pipe leaks, stereo grounding issues, etc, but I don't think any of those are what I'm dealing with.

It's a pretty faint whining/whistling sound that seems to track ONLY with engine speed, noticable between ~1800rpm and 5000rpm. When I say that it tracks only with engine speed, I mean that throttle position, engine load, boost, gear, etc seem to have no effect on the pitch, sound, or volume of the noise. It sounds the same whether I'm slowly revving the motor in neutral or going WOT in 3rd gear. Sounds the same when the engine speed is increasing, decreasing, or holding constant.

I hear it coming from the engine bay when I'm in the car, but when I stick my head under the hood, I can't pick it out.

I hear it whether the stereo is on/off. It is an aftermarket deck, but I've had the same deck for 2 years, and I've only noticed the sound in the last couple of months.... though I can't remember exactly when it started because it's a fairly innocuous sound.

Any thoughts? The fact that I can't figure out what it is is more annoying than the sound itself. lol

 

[pavone]

i know on non turbo proteges you can hear this more but sometimes i can hear some tranny whine, i heard it before with my car before i installed my exhaust, now the car is too damn loud to hear but its a slight whine almost superchargerish sounding but very faint. alsmot like a whirling sound.

 

[mazdaspeedp]

probabley just the noise the turbo makes after the bearings are kindof ******

 

[Knox Joe]

I know you said you don't think it is the mani, but I'd take a serious in depth look at it.

 

[dmention7]

i know on non turbo proteges you can hear this more but sometimes i can hear some tranny whine, i heard it before with my car before i installed my exhaust, now the car is too damn loud to hear but its a slight whine almost superchargerish sounding but very faint. alsmot like a whirling sound.

I know I have some tranny whine in a couple of gears, but this is different. It follows engine speed, regardless of gear, or whether the clutch is in or out.

probabley just the noise the turbo makes after the bearings are kindof ******

This noise is regardless of load, boost, or any other function of the turbo spooling. It strictly follows engine speed, with no lag or variation. Not that it would surprise me much if the turbo is going... heh

I know you said you don't think it is the mani, but I'd take a serious in depth look at it.

I would've assumed it would vary somewhat with load or throttle position if it was in the exhaust mani. Am I incorrect in that? Regardless, I'll take a look when I get the chance.