I'm in the process of installing an Autometer boost/vac gauge, and having some issues. I teed off of the line to the BPV (the one that almost everyone uses) and hooked the gauge to check if it worked before I mounted the thing.
Well, it reads 0psi when the car is off, as it should. Turn on the engine, and it reads about 15 inHg in vac. However, when I rev the engine, it goes up to 5 inHg for a second, then falls back to 15 inHg as I rev it up well into boost (past 3k).
I triple checked all connections, and cannot find a leak. Also, when i blow on the hose, I can get it to read about 3 psi, so I know the gauge will indeed read pressure.