I was on @Gus jagrepair.com and at one time Gus doctored up the vacuum line that comes off the lower passenger side (LHD car) of the throttle body. On his example someone had inserted a white nylon barbed coupling in the line. My question is what does this vacuum line supply? Mine goes into the compartment that houses the electronics under the hood and then runs under and along the windshield cowl, only to disappear from view.
I created a smoke machine and found that this fitting that goes into the throttle body was missing its plastic grommet, at least most of it and its o-ring. Hence its leaking. Think I've solved that but would like to know whats on the other end.

Michael

 

I believe that line goes to the Brake Servo Master Cylinder..