Whistling sound upon acceleration

I've been having this odd whistling sound coming from my engine area for a while now and it's driving me nuts. The whistling would coincide with my acceleration and after about 3500rpm i wouldn't be able to hear it anymore

It's not my intake elbow or air filter, i've systematically disconnected and checked all of that. No engine light and the car idles fine so i'm thinking it's not a vacumn leak.

I was able to pinpoint the noise to a general area - the idle control device.
When i disconnect the idle air tubing that goes into the plenum the noise goes away.

It's not due to a loose connection between the tube and plenum because i actually put liquid gasket around that connection and the noise was still there.

The best I can come up with is that something down stream of that tube has a leak, a crease, a gap etc and when a specific air velocity goes through it it will make a whistling noise. The noise has been there for months now and no indication of any performance decrease.

I know this is a pretty specific/obscure issue but i'm hoping someone might know what the issue is cause the noise is maddening. Thanks!

Whistle tips yo.

What air intake is that?

is the whistling coming from the large thing on the bottom right of the pic?

Sorry, for clarification that is not my car. I just googled an image of the idle air tube (item circled in red in the top right) for reference.

Bro, it's obviously from your turbo

1MOREMOD wrote

Whistle tips to.

Naw that's only in da mornin

dreamspeed wrote

Sorry, for clarification that is not my car. I just googled an image of the idle air tube (item circled in red in the top right) for reference.

I thought you were joking and supercharged your car and asked why does it whistle...

Tylenol Jones wrote

Naw that's only in da mornin

'posed to be up cookin breakfas or sumfin

I've read of a similar case where it was just the plenum that was not properly mounted or the air guide from the intake but you're right it could be the idle control valve.
That part has an extended factory warranty. Just take it to a good bmw Indy shop and should be no issue to figure out.

JoeM3SSII wrote

I've read of a similar case where it was just the plenum that was not properly mounted or the air guide from the intake but you're right it could be the idle control valve.
That part has an extended factory warranty. Just take it to a good bmw Indy shop and should be no issue to figure out.

JoeM3SSII wrote

I've read of a similar case where it was just the plenum that was not properly mounted or the air guide from the intake but you're right it could be the idle control valve.
That part has an extended factory warranty. Just take it to a good bmw Indy shop and should be no issue to figure out.

Can't be the plenum not mounted correctly, I mean I've taken that thing on and put it back on over ten times now.

The only thing I've pin pointed it to is the noise goes away when I disconnect the idle air tube from the plenum and comes back when I reconnect it.

OP,

I have had the same whistling sound upon accelerations for the last few months. Interestingly my idling has been fluctuating a lot in the same time frame and I was reading about the idle control valve going bad as a reason for the fluctuating idling. So not sure if its all related.

The sound is annoying and bothered me initially but I just ignored it telling myself maybe its one of the many abnormal sounds associated with our cars. If something is indeed going bad I hope the car will let us know in some other way .

Anyways please keep us posted if you find anything more. Thanks!

I have this on my e90, but not my e92. Mine coincides directly with the pushing/releasing of the gas pedal.

ive often wondered if an improperly mounted felt undertray causes the noise. I have it but only with the top down.

Munichm3 wrote

Bro, it's obviously from your turbo

possibly from BMW Twin Power Turbo oil?

decimation1 wrote

I have this on my e90, but not my e92. Mine coincides directly with the pushing/releasing of the gas pedal.

likely going to be a drive belt or pulley issue for you. I would look into this.

op, you might want to look into this: http://www.bimmerfest.com/forums/showpost.php?p=10333658&postcount=3

Flying Ace wrote

op, you might want to look into this: http://www.bimmerfest.com/forums/showpost.php?p=10333658&postcount=3

Unfortunately my whistling noise happens while the car is stationary. I can the gas while the car is parked in neutral and it'll make the noise.

Highly doubly it's pulley related either, I'm like 99% sure the noise is "air" related.

From my research there are multiple sources of "whistling" noise. Could be pulleys, vacuum leaks, issues with air flowing through side mirrors/underbody parts while moving etc.

Even from the replies I'm seeing this thread there are probably multiple causes.

My car has also developed a buzzing sound right between 2900-3000rpm lol. Most likely a loose metal piece somewhere... sigh....

dreamspeed wrote

Can't be the plenum not mounted correctly, I mean I've taken that thing on and put it back on over ten times now.

The only thing I've pin pointed it to is the noise goes away when I disconnect the idle air tube from the plenum and comes back when I reconnect it.

Then it sounds like the idle control valve fails to close shut when you accelerate. This could be from deposits in the ICV. The valve leaves open a slot that bypasses additional air around the butterfly valves and the engine suction blows it like a whistle. In idle the valve is not closed so your idle will be normal.

why are you going through that trouble when there is an extended BMW warranty bulletin on the ICV ? you can just get bmw to replace it for free.

JoeM3SSII wrote

dreamspeed wrote

Can't be the plenum not mounted correctly, I mean I've taken that thing on and put it back on over ten times now.

The only thing I've pin pointed it to is the noise goes away when I disconnect the idle air tube from the plenum and comes back when I reconnect it.

Then it sounds like the idle control valve fails to close shut when you accelerate. This could be from deposits in the ICV. The valve leaves open a slot that bypasses additional air around the butterfly valves and the engine suction blows it like a whistle. In idle the valve is not closed so your idle will be normal.

why are you going through that trouble when there is an extended BMW warranty bulletin on the ICV ? you can just get bmw to replace it for free.

Do you have a link to the bulletin? I googled this prior and only found some posts where people got a letter from BMW indicating an extended warranty for the ICV but it was VIN specific. Some people called their BMW to check and they weren't covered. Personally I never got a letter regarding ICV warranty.

Also, if I were having idling issues or getting a ICV error code I'd be more inclined to bring it into the dealer but currently the cause of whistling is still TBD. I've dealt with BMW warranty before and I'm pretty sure it's going to go down like this....

Bring car in and complain it's the ICV. SA will say ok but we gotta do our own diagnosis first and it's going to be 200-300 bucks. If the repair is covered by warranty then your diagnostic fee will be waived... they keep my car for a day or two and tell me there's no issue with your ICV. 300 bucks down the drain

OP -- any luck resolving?

http://www.m3post.com/forums/showthread.php?p=22306187

I agree that the sound is annoying as hell. A big part of this car is the noise the V8 makes -- the incessant whistle under 3,000 RPM really detracts from it.

Nope, going on a year with this nuisance.

Next logical step is to remove the idle control unit and clean it throughly but it's more of a pain to remove than I thought and I haven't gotten around to it