cjoenck

I noticed a new sound driving this weekend. Under load I can hear a high frequency whistle sound that stops when I take the foot off the accelerator. When applying load, the sound is back.

- It is not rev dependent
- It is not speed dependent
- The frequency does not change

It is a pure on/off under load/no load.

Vacuum leak? I don't see any other symptoms associated with a vacuum leak. The coils are new (1 year).

Any ideas?

Vandit

I think my car has this too. From what I've observed in my car, however, it is rev dependent (or at least most obvious at higher RPMs, on and off throttle). It's not speed dependent since it goes away if I take the car out of gear and let the revs fall. I assumed it might be induction noise from my EvoMS cone intake. I think others have said it's the sound of the engine cooling fan moving air through the shroud.

Goughary

I have it too. No clue what it is....

Well - mine is rev dependant...high revs - and I have the scream...

Rocket Rob

I would suspect either a vacuum leak or a leak in the cooling shroud. For a while, I had a torn rubber between the fan shroud and the heater blower. It made a noise. Once I replaced it, the noise went away.

Goughary

interesting - Mine is torn....figured it wasnt an issue...since the hole is so small...

cjoenck

To clarify, the frequency of the sound does not change with speed or revs. It is not noticeable when idling however. Also, the car is a C2 Tip.

I have a hard time wrapping my head around a wind noise because it is purely load dependent as far as I can tell. Air flow through the shroud should be rev dependent as fan speed changes with rev changes, doesn't it.

What about fuel injectors? Do they get a frequency signal? The sound appears more electrical than mechanical - if that makes any sense.

Vandit

Good call on the shroud leak. I have trouble w/ that piece at the top that connects to the blower. I usually end up w/ a bit of a gap on the back, between the shroud piece and the main shroud that goes under the intake manifold.

azander

I also have a tip (if it may be tranny related) and I hear a whirl/whistle at a relatively constant pitch. My heater duct is visibly cracked on top. Perhaps that is the culprit (in my case)...

ThomasC2

I had a strange sound just a month ago and I thought the whistle sound was due to a leak. But it ended up being the wheel of the fan belt sensor that had stuck and was draging against the belt creating the high pitch sound. so check the sensor!

Thomas

frankvan

+1 on the alternator belt sensor. i searched for months for the source of my high pitched whistle that didn't change with revs, never suspected the belt sensor as it should change with revs, but that's what it was.

mc_renn

+2 on the belt sensor. put a shot of penetrating oil overnight and it was gone