Mixture Adjustment

["Dan Sinclair" <sinclair@prospro.com>]

This is a dumb question, but I've confused myself and need a second option.

The Bentley indicates that the mixture (CO) adjustment screw should be
turned clockwise for (+) and counter-clockwise for (-), suggesting that
clockwise will increase the CO level, and counter-clockwise will decrease
the CO level.  So, and please correct me if I'm wrong, clockwise (+) is
enriching the mixture, and counter clockwise (-) is making it leaner -
correct?  The lower the CO number, the leaner the mixture, right?

I'm going to have to take my '88 90 in to have the mixture checked via a CO
meter, but I want to understand what they'll be adjusting if necessary.

Also, I determined that my dealer or the previous owner's mechanic removed
the rubber plug that hides the mixture adjustment screw, but didn't replace
it.  The hole has been open for months if not years depending on who removed
it.  Would this have any effect on the engines operation.  Can air enter the
intake system through that hole?

Thanks,

Dan Sinclair
1988 Audi 90, 69K mi.
Walla Walla, WA
Pics&details: http://131.107.68.28/a4.org/registry/details.asp?car=761