i'm having a problem. at idle the gauge is showing vac, and when i drive it or rev it up the gauge will only go to 0, no boost. nothing is wrong with the gauge so i'm having a vaccum problem?? anyone had any problems like this??
pleaase help.

 

Bypass valve stuck open maybe??

 

mine was doing pretty much the same thing... i put a new belt on, mine was slipping..not sure how old yours is, but mite be worth checking

 

Belt slip, bypass valve, ignition issue, could be a ton of things, is it breaking up?