Purpose of hose outlet on top of cylinder 1?

[320iAman]

I'm not sure the purpose of that hose, outside of adding another avenue for PCV(Positive Crankcase Ventilation) to work thru.

After further working with hose, the purpose of this hose is clear. It taps the pcv going to the entrance of the throttle body thru the large rubber boot where oil vapors, ect get vacuumed past the butterfly valve going into the throttle body from the bottom to the top-inside the throttlebody, this tap of pcv- increases idle rpm for free, pinch closed this tap line and idle will drop-so its purpose is too tap pcv and keep idle up-without having to adjust the butterfly valve and so forth. PCV lowers idle rpms-the tap increases idle rpms for free. lol

Putting it another way-it adjusts-lessens the effect on idle that the pcv system has on the idle and the running motor.

Your all welcome

Randy