[titium]

I have this whistling noise upon cold start of my 135i.

It sounds like air is escaping from somewhere and doesn't sound like alternator whine. I did manage to find one of the meth bungs on my charge pipe was loose, tightened that up and it's not as bad but it is still there and noticeable from in the cabin (suggesting this was only part of the problem).

when you first start the car is it non existent. As the RPM begin to fall it starts and by the time the RPMs have dropped to the normal idle RPM the whistle is gone and doesn't return until the engine is cold started again.

The car does it every cold start.

Anyone have any insight? or does anyone know the sequence of events in the cold start procedure?

Also it's not easy to bring the car to a shop to diagnose without leaving it overnight..... no performance or drivability issues so far as I can tell.

[EB89]

Any new additions to the car?, is your charge pipe tightened enough? Mine poped off under heavy load one time.

If you have the hood up and someone else rev the car can you pin point the location of the whistle?

[7smurfs]

Originally Posted by EB89

Any new additions to the car?, is your charge pipe tightened enough? Mine poped off under heavy load one time.

If you have the hood up and someone else rev the car can you pin point the location of the whistle?

Yep check that hoses are on properly on the CP and ensure that you've correctly installed the clamps.

My Cp popped off twice on heavy load because i fail installed the clamps properly.