Answer to the mysterious vacuum valve

[alves at email.unc.edu (Carlos Alves)]

I noticed a couple of people have asked questions regarding the 
mysterious "vacuum operated air flap" on the side of the intake, and no 
one knows what it is. This applied to me because I recently lost the 
switch and my 16v would not idle worth a dime when cold. I found out 
where it is in the Bentley manual, it is in the Fuel system - Gasoline 
section, 5-55. Below a certain degree, the vacuum control valve opens 
and blocks the fresh air inlet and diverts air flow to the warm air 
inlet which is heated up by exhaust heat. So if you remove the little 
vacuum switch, when the car is cold it will cause a vacuum leak. 
Anyways, just figured I would spread the knowleadge.


-Carlos