Originally Posted by mlifxs
I have around 102k miles on my N52 328i. My car does something like that when all three below are occurring:
a. Car is in D, P or R and car is not moving.
b. Foot on the brake.
c. AC is off.
If I change any of the above, the idle increases slightly and the vibration is gone.
Similar issue on my N52 128i. RPMs would dip below 6000 intermittently while stopped at a stop light, having the AC on would solve this issue somewhat. Brought it in to dealer, they found no faults but "adjusted idle values" which increased the idle RPM to around 7250-7500 about 2 months ago. No issues since, engine is smooth as silk.