alright guys my boost gauge only goes down to zero. It goes up under boost, but not down at idle. Its an aftermarket boost gauge installed on a s5 turbo swapped car. I can't imagine i have a vacuum leak big enough for vacuum to be 0 right? The car runs and idles ( a little roughly).

 

Where is the boost/vacuum source for the gauge plumbed into on the engine? Several of the nipples and lines are fresh air ports which lead to a pickup in front of the throttle plates. Plumb the line from the boost gauge into the line going to the pressure sensor on the passenger shock tower.

 

Yeah, i think i accidently got into one of the fresh air ports. After much searching i eventually found out about this. So the pressure sensor also needs to be hooked up to the real vacuum line and not a fresh air port too right?

 

Yes.