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JFairman JFairman is offline
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Join Date: Jul 2006
Location: S. Florida
Posts: 7,212
OK, thanks for your descriptions.

I'm familiar with the high idle throttle bypass device on CIS and L-jetronic, and always called it an auxilliary air valve.

If your description is correct, then there is no AAV on '87 930 K-jetronic.
There is a large 3-4" diameter gold cad plated vacuum operated valve thing that looks alot like the one in the picture in the other post link but it is called a deceleration valve on an '87 930.
It is activated by manifold vacuum at the same time as the recirculation valve that recirculates boost pressure back to the inlet of the turbo when you lift the throttle quickly, while the deceleration valve does the same thing between the the intake manifold and the airbypass housing to cut down on the amount of air sucking down on the CIS metering plate.
Anotherwords it leans out the mixture to a degree on deceleration to lower emissions, use less gas, and maybe cut down on popping and flames coming out of the exhaust while decelerating.
The car will run fine without it, but will use more gas on deceleration.
Old 11-24-2007, 04:06 PM
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