Anyone know anything about mass airflow sensors?

[Nute]

I've come to the conclusion that I can't delete this thing. I think it's made by Bosh, it's on my BMW, originally housed in an ugly plastic box between the intake filter and the induction manifold. Appears to have a spring loaded metal flap in it which is opened progressively as airflow increases, I assume to vary the timing.

It was originally mounted so that the pivot spindle around which the flap rotates was vertical, so the flap thing moved on the horizontal plane - not influenced by gravity. Any idea if I can rotate it so the spindle is horizontal and the flap thing will move in the vertical plane? The flap thing doesn't have much mass and it still closes against the stop when rotated.