Semi-hypothetical questions.

In which position is an auxiliary air valve most prone to failure?
In the open position, or closed position?

Also, is it possible for said valve to fail to a point where it will function, that is the valve moves, but doesn't fully close? My cold idle is consistent with it's operation, but when it's warm, to achieve a decent idle speed, I need to choke the idle screw almost closed.

__________________
RIP: 80 300SD
RIP: 79 450SEL
2002 E430 4matic (212,000km)
2002 ML500 'sport'

____________________________
FACEBOOK: PANZER450