E90/E92/E93 BMW M3 Plenum Defect (How To Fix Whistle While Applying Slight Throttle)

There is a common defect on stock E9X plenums that causes a high pitched whistle at light throttle. It is more pronounced when a cold air intake is installed, and a pretty annoying sound. In this video I show you what causes it and how to fix it.

Here is a thread where other people had the same problem: https://www.m3post.com/forums/showthread.php?t=1417824

FrozenE92M3 wrote

There is a common defect on stock E9X plenums that causes a high pitched whistle at light throttle. It is more pronounced when a cold air intake is installed, and a pretty annoying sound. In this video I show you what causes it and how to fix it.

Here is a thread where other people had the same problem: https://www.m3post.com/forums/showthread.php?t=1417824

So I was referred to this thread and the thread you shared which all seem to be very synonymous to what I've been experiencing. Was the noise that you experienced the same in my video (attached)? Best heard around 9 sec and 13 sec. Just want to be sure before I spend time on the plenum this weekend. Thanks!

AceBeezy wrote

FrozenE92M3 wrote

There is a common defect on stock E9X plenums that causes a high pitched whistle at light throttle. It is more pronounced when a cold air intake is installed, and a pretty annoying sound. In this video I show you what causes it and how to fix it.

Here is a thread where other people had the same problem: https://www.m3post.com/forums/showthread.php?t=1417824

So I was referred to this thread and the thread you shared which all seem to be very synonymous to what I've been experiencing. Was the noise that you experienced the same in my video (attached)? Best heard around 9 sec and 13 sec. Just want to be sure before I spend time on the plenum this weekend. Thanks!

Yes that does sound like what I had! Now the key is, does that sound only occur when giving slight throttle? If it's a constant sound that's very quiet and doesn't need throttle input it might be the shape of the side mirrors, my mirrors sometimes whistle when wind hits them because of the shape.

But the video you posted I am 99% sure that's the plenum issue. Doesn't hurt to check.

FrozenE92M3 wrote

AceBeezy wrote

FrozenE92M3 wrote

There is a common defect on stock E9X plenums that causes a high pitched whistle at light throttle. It is more pronounced when a cold air intake is installed, and a pretty annoying sound. In this video I show you what causes it and how to fix it.

Here is a thread where other people had the same problem: https://www.m3post.com/forums/showthread.php?t=1417824

So I was referred to this thread and the thread you shared which all seem to be very synonymous to what I've been experiencing. Was the noise that you experienced the same in my video (attached)? Best heard around 9 sec and 13 sec. Just want to be sure before I spend time on the plenum this weekend. Thanks!

Yes that does sound like what I had! Now the key is, does that sound only occur when giving slight throttle? If it's a constant sound that's very quiet and doesn't need throttle input it might be the shape of the side mirrors, my mirrors sometimes whistle when wind hits them because of the shape.

But the video you posted I am 99% sure that's the plenum issue. Doesn't hurt to check.

You're the man, thanks for the feedback! Yes, it ONLY happens with slight throttle (between 1500-2000ish rpm). I'm replacing the plenum as I am part of the carboproject group buy, hope that solves it!

I replaced my plenum with a carbon plenum and I still have the whistle. Any idea?

itsnotme wrote

I replaced my plenum with a carbon plenum and I still have the whistle. Any idea?

Perhaps the aftermarket carbon plenum still uses that OEM ring gasket that loosens itself causing the whistle. Take your carbon plenum off and look for that gasket thing that I showed in the video I posted.

Picked up my new (to me) E93 yesterday and noticed that whistle right away... adding this to “the list”.