New 2008 BMW 318i with whistle between 60-80 km/hr

[adin]

Hi All

I've dug through a number of forums and my dealership is a bit puzzled. New car - 4 months old - 2008 318i gasoline, and it gave no problems until I reached a mileage of around 2000 km. It then developed an engine whistle which you can only hear inside the car.

The pitch of the whistle does not vary, and the whistle is present from around 60 to around 80 km/hr with volume peaks at around 60 and around 80. It doesn't change regardless of whether I'm in 4th, 5th or 6th gear.

Mostly it's a pure whistle tone, but sometimes it sounds a bit metallic. It's generally there during acceleration, and becomes more quiet when I stop throttling, but if I let the car slow down without throttle from above 80 it whistles all the way down to 50-60.

The whistle isn't there when the engine is cold, and as the engine warms up the whistle becomes more noticeable. At fast motorway speeds, above 120km/hr, it's always there in the background.

Any ideas? Since this engine is comparatively new, there doesn't seem to be much information available for it.

Cheers
Adin

[adin]

OK, some research on this side and other WWW sites gives me a few possibilities, but can anyone help shed any more light??

First question: does anyone have a 2008 318i, and do you get any fixed-pitch whistles? The dealership is saying that it might be normal, but it only started after around 2000km so I dispute this!

Ideas: - HELP!! Please comment guys 'n' girls!

- MAF sensor - mass airflow sensor at inlet
- DISA valve
- ICV (what's this?)
- Vacuum leaks? Any idea how many vacuum systems we've got on this engine?
- Air filter and housing?

Thanks!!!
Adin