[obsoletepower]

Hi guys, so I have been a longtime lurker on the forums but now I do have a question regarding this noise I am hearing. It happens a second after I press on the throttle pedal and roughly a second or two after I depress the throttle. It doesn't seem to happen or perhaps it is not audible unless I put the car in Sport mode. It is a very short squeak/whistle, maybe half a second in length. Seems to be coming from underneath the car and really it is only audible with the radio turned off. I do hear it even with all windows closed. Anybody want to take a stab at what this might be? It is a 2016 340xi with 23,000 miles, no MPE and completely stock.

I appreciate any help/comments.

[rak299]

If you are talking about hard acceleration, it could be slipping belt

[obsoletepower]

It happens even if I just touch the throttle slightly so I doubt it is a belt slip.

[rak299]

This is an AT? (If 6MT, what I am saying will not apply) Does it happen if you are coasting and then step on the gas? Only at startup? If it only happens in sport mode and seems under the car, it seems that it must be in the transmission. There are vacuum-driven modulators and other magic stuff that work differently in sport mode.

Are you still under warranty? If so, anything inside the transmission is expensive. Take it into the dealer.

[obsoletepower]

Originally Posted by rak299

This is an AT? (If 6MT, what I am saying will not apply) Does it happen if you are coasting and then step on the gas? Only at startup? If it only happens in sport mode and seems under the car, it seems that it must be in the transmission. There are vacuum-driven modulators and other magic stuff that work differently in sport mode.

Are you still under warranty? If so, anything inside the transmission is expensive. Take it into the dealer.

It is an auto. I can hear the noise when coasting then pressing gas pedal and happens after depressing gas pedal as well. I can hear it in sports mode but I think it happens in comfort as well but maybe not as loud. Also, it doesn't seem to happen when starting off from rest.

The car is still under warranty for a few more years but before taking it in I want to try and pinpoint this to at least a general area. Noises are some of the worst problems to have because in some cases they are almost impossible to diagnose. I am going to try and capture this noise and hopefully post a clip of it soon.

I really appreciate your suggestions!

[Apwf30]

Originally Posted by obsoletepower

It is an auto. I can hear the noise when coasting then pressing gas pedal and happens after depressing gas pedal as well. I can hear it in sports mode but I think it happens in comfort as well but maybe not as loud. Also, it doesn't seem to happen when starting off from rest.

The car is still under warranty for a few more years but before taking it in I want to try and pinpoint this to at least a general area. Noises are some of the worst problems to have because in some cases they are almost impossible to diagnose. I am going to try and capture this noise and hopefully post a clip of it soon.

I really appreciate your suggestions!

I know this is a bit old but I stumbled across this post, i seem to be having the same issue. Did you get a diagnosis from the dealer? Thanks