Air box flap solenoid

[neckarsulm]

Is there a reason they use 12v solenoid & then vacuum rather than connect a 12v motor directly to the flap as surely would be more reliable ?

I can't think of a good reason.
It does remind me of something else though;
On TDIs with variable vane turbos a remote solenoid (n75 valve) would alter the vacuum to the turbo and open and close the vanes accordingly.
On 2.0 TDI 170 A4 Avant they ditched that and incorporated the N75 into the turbo so it became electrically operated.

This makes me think it's a packaging issue;
The airbox is tight as it is behind the headlamp, to have solenoid in their too wouldn't work
The inlet manifold is right up against the slam panel so again too tight
The exhaust valves have loads of room but the electrics wouldn't last long exposed to such heat and vibration

[MB2]

Makes sense can fit an air-line just about anywhere, just thinking that my bikes have had valves both in the exhaust pipes (4-Strole) & in the cylinder block (2-Stroke) and were always servo operated, also I guess one pump can operate multiple valves whereas would need a motor for each otherwise, + cables to snap if remotely activated ?

[adsgreen]

Is there a reason they use 12v solenoid & then vacuum rather than connect a 12v motor directly to the flap as surely would be more reliable ?

I don't like most vacuum systems but they do have some advantages and the main one is that I'd say a leccy motor would be less reliable.
You can tranmit alot of "power" using a vacuum pipe and with minimal moving parts it's pretty reliable (until you get a leak).
Also if a part sticks or has increased resistance for whatever reason (like an exhaust flap or airboxc flap) then theres no load on a motor. A stuck or struggling leccy motor will burn out pretty quickly. It's not really affected by heat that a leccy motor would be.
Finally, it's a lot cheaper