[BDO]

I actually have a 640i, however that forum is not very active so I thought I'd ask here.

I hear a very high pitched noise ( ~10000Hz) under acceleration, when throttle opening is 70% or larger, and only between 4000-5000rpm. The sound builds up in that rev range, then goes away.

Diagnostics don't show any fault codes, there is no performance loss, or anything else to go by.

Car is under warranty, however the dealer is stumped and doesn't know/is reluctant to troubleshoot as there are no problems other than the noise.

Any idea/direction?

[Bbb34]

What about if the car is stationary, do you still hear this in the same RPM range ? I have, well, not a high pitch, but some humming noise coming from my engine at 2600-2800 RPM same on acceleration, cruising and stationary.
Unfortunate thing for me, this happens to be highway cruising speed RPM range, and while it's not very loud, I don't feel it should be there at all.

Dealer "can hear it" but has no idea what to do "until it gets louder", so I'm curious what you find.

[top ramen]

I got a humming noise at the right side of the engine where the turbo is yesterday after I installed my jb4 and did a few hard runs. I was asking for help at n54tech and one member said it was my boost solenoid that has gone or starting to go bad. Watch the video in the link to see if that's the noise you're hearing. http://www.n54tech.com/forums/showthread.php?t=39294

[BDO]

Originally Posted by tomyang

I got a humming noise at the right side of the engine where the turbo is yesterday after I installed my jb4 and did a few hard runs. I was asking for help at n54tech and one member said it was my boost solenoid that has gone or starting to go bad. Watch the video in the link to see if that's the noise you're hearing. http://www.n54tech.com/forums/showthread.php?t=39294

No, nothing like that. Mine is a really high pitched noise audible in the cabin as per my initial post.

I dropped my car off for some other work today, and in sheer frustration at not knowing where to start asked them to check the boost pipes and the boost solenoid.

[BDO]

No problems found with the boost solenoid or boost pipes (i.e. no boost leaks). Looks like they will be changing the turbo next, but I need the car today so will make a plan for that later.

[kckc1016]

any update to this, i have to get something similar fixed

[BDO]

Originally Posted by kckc1016

any update to this, i have to get something similar fixed

Nope. They didn't change the turbo, I could possibly push for that but speaking to the master tech I really don't think it's that. Pretty stumped at the moment.

[Secret_Asian]

can you record it and show us

[EV0LVE]

Serpentine belt?

[AWF87M2]

I am experiencing the same buzzing noise as the one from this video below.

[AWF87M2]

Found it! So any of you 535i owners that are out of warranty and experiencing the same buzzing noise as the one from the video, you need part# 11747626351 replaced. Note, this is only for PWG cars.