Non-return valve

[Bulletproof_E82]

This part to be exact:

http://www.4wheelsautoparts.com/images/bmw-parts/11611312737-OES.jpg

What is the proper direction to install this. I've got random misfires and have troubleshot almost every possible part. My air pump valve had the vacuum lines backwards, so I'm wondering if this is installed the wrong direction also. Thanks for your help!

[kevinwilly]

I would just suck on it. The direction you can get suction through is the side that goes toward the intake manifold. (you know, so vacuum can reach the air pump valve)