[Jerich0]

Hello guys...

Just wanted to know if this is normal... My car whistles in second gear, it does not matter how hard I push it and its more noticeable just when I am about to change from second to third gear... It does sound a bit like the turbo but its not noticeable in all the other gears, this is in the auto tranny... Do you guys have it too?

Thanks!
JC

[Dr. Indiana Jones]

My M235i auto also exhibits a faint temporary whistling sound upon initial acceleration. The consensus on this website is that this is caused by the turbo (single turbo, dual scroll) spooling-up on initial acceleration (nothing to do with the tranny), and thankfully is normal and is nothing to worry about. At first I too found it a bit annoying, and was concerned something might be wrong, especially since the outgoing 335i was a twin turbo single scroll set-up w/o any whistling noise. Anyway, after a while you get used to it and it is no big deal. Some folks even prefer the whistle sound as an indicator of power. On a positive note the single turbo dual scroll and N55 engine is supposedly 15% more fuel efficient and exhibits less turbo lag, albeit has nominally less HP and torque, than the outgoing twin turbo single scroll N54 set-up. Given the lighter weight of the M235i, it's a tad faster even than the outgoing N54 335is.

[dharo1]

Originally Posted by Jerich0

Hello guys...

Just wanted to know if this is normal... My car whistles in second gear, it does not matter how hard I push it and its more noticeable just when I am about to change from second to third gear... It does sound a bit like the turbo but its not noticeable in all the other gears, this is in the auto tranny... Do you guys have it too?

Thanks!
JC

Might be doing it at every gear after 2nd but, since you're going faster after 2nd, wind noice + speed + road noise doesn't let you hear it.