Flutter Noise in air induction under aceleration

[Wess McCoy]

Having had success finding answers to technical questions on the Porsche side of the board, I thought I would try to get an answer to a technical question on the BMW side.
I had an oppurtunity to ride in a 96..? 850csi yesterday and listened when the owner pointed out a noise...under acceration.....a flutter noise almost like a flap or induction door was flapping as rpm's increased....

He was told by his service guy, that they would have to remove the dash for a $grand$.....to fix the problem....
It's hard to believe thet the dash has to come out, but will wait for somone else's experience or advise.....

The noise seems directly affected/ caused by aceleration....and doesn't sound like it in the dash, more in the engine air induction ducting....maybe one of the noise baffles....?

Any help would be appreciated....

[trj911]

I'm not sure about the 8 series cars but the 7 series has 2 flapper doors that open when you drive to provide fresh air to the system. Some people prop them open all the time to allow for fresh air in the A/C system when sitting still. On a 7 series the doors are at the back top of the engine compartment.

[Wess McCoy]

Thanks for the input....
At least we know that something like a flapper door exists, now to find it on the 850...

wess

[snowman]

Its caused by the baseball card thats held to the wheel by a clothspin. The previous owner probably forgot to remove it when he sold it.

[Wess McCoy]

Nah!
First thing I checked!
Definately in the induction.....