Shep 1.8T

hooked up the ole' air compressor and ran about 10 psi through my stystem. The only leak I found was where the BPV and the return to the intake hose back meet. That shouldn't really matter though because that hose feeds into the turbo intake hose is before the compressor, and wouldn't really effect vaccum. I was able to pinch that leak shut and it got dead quiet as far as we both could tell, yet I am still only making 15 in HG for vacuum, which isn't right for my car. I should be making around 19~20 in HG while idling. I'm considering replacing a lot of the hoses comming off the intake manifold that lead to those 1 way valves. Any suggestions?

Someone else suggested turning the car on and systematicly plugging each of the fittings comming off the intake manifold with my finger and once my vaccum rises, identify that hose and replace all the lines etc, comming off that fitting.

dgkula

I took most of the vac system apart and individually tested components: check valves, SJP, etc.

Shep 1.8T

I started the engine and then removed each of the 3 major hoses comming off of the intake manifold, and held each closed with my finger over it, completely sealing the fitting off. No increase in vacuum pressure. I even tried plugging two of them and nothing.

dgkula

They won't show up in a pressure test but can adversely impact boost.

dgkula

Also what are your long-term fuel trims? Maybe you don't have a boost leak ... but something else

RichMN

I've found vacuum leaks by using a can of gumout carb cleaner. First I hooked up my vag software and monitored a channel (I can't remember which one, sorry). Then I squirted a little carb cleaner at the end of each vacuum fitting. When I hit the vacuum leak, the channel I was monitoring changed.

I think the Bentley manual talks about doing something like this too.