Need Help - 2004 E46 M3 loud whistle at 4.5k RPM

[s2kdagjd]

Hey Guys,
Anyone experienced this sound?
A mechanic i used thinks its the DIff....but its RPM specific regardless of speed.

[eacmen]

Do you have video of the sound?

[s2kdagjd]

the link of the video is on the post...do you see it?

[heinzboehmer]

Huh that's a noise I haven't heard these cars make before. Reminds of the noise that some shop vacs will make when you extend the hose too much.

Anyway, have you checked all vacuum hoses under/above/around the intake? Assuming it's engine related and since it's rpm specific, you could have some hold it at 4.5k rpm while you try to pinpoint which part of the engine bay its coming from.

[s2kdagjd]

Huh that's a noise I haven't heard these cars make before. Reminds of the noise that some shop vacs will make when you extend the hose too much.

Anyway, have you checked all vacuum hoses under/above/around the intake? Assuming it's engine related and since it's rpm specific, you could have some hold it at 4.5k rpm while you try to pinpoint which part of the engine bay its coming from.

it only makes this noise under load so its hard to pinpoint.

[s2kdagjd]

bump

[heinzboehmer]

You can get the car up in the air and apply brakes and throttle at the same time to simulate load. Just don't knock it off the stands or walk close to the spinning rear or anything like that.

[Sharocks]

Are you supercharged?

[ChapterM3]

I'm wondering if there's a rip in one of your ITB couplers that's opening or closing up at that specific load/rpm range causing air to move over a different surface and almost whistle like that as it does it. Does it happen at full throttle? or a specific position of the gas pedal? Curious about this one

Edit:
- What happens before and after 4.5k? everything's normal or are there other sounds?
- Does it sound like its coming from the engine back or anywhere else in the car? Has a passenger agreed that it's coming from the same location?
- Any mods done to the car?
- ANY recent work done to the car?

[s2kdagjd]

Are you supercharged?

NO

[s2kdagjd]

I'm wondering if there's a rip in one of your ITB couplers that's opening or closing up at that specific load/rpm range causing air to move over a different surface and almost whistle like that as it does it. Does it happen at full throttle? or a specific position of the gas pedal? Curious about this one
i did see a small leak in one of the ITB connectors.
after about 6K RPM sound goes away

Edit:
- What happens before and after 4.5k? everything's normal or are there other sounds?
normal
- Does it sound like its coming from the engine back or anywhere else in the car? Has a passenger agreed that it's coming from the same location?
engine
- Any mods done to the car?
CAI and Muffler
- ANY recent work done to the car?[/QUOTE]

[ChapterM3]

If you saw a small leak in one of the couplers I would start there and see what else is going on - what was the leak? Oil residue or how did you see it? I would absolutely start there and see what's going on