My neighbor just got a new motor put in his '02 GT. One of the go-fast-goodies is a turbo. The turbo works, but we can't tell how much. He has a boost gauge installed, and if I'm right the needle should be at zero boost but it sits at around 20 below the zero - tap the gas and it jumps up to zero. If the needle sat on the zero at idle you could tap the gas and it would hit just between 8-10 lbs of boost - like it's suppose too. Anybody have an idea of what's going on?

 

A turbocharged setup will never show boost unless the engine is under load (i.e. accelerating, towing, foot-braking, etc). Just tapping or even revving the throttle in neutral does not produce enough airflow through the turbo to make boost.

Is it a combination vacuum/boost gauge?

If so, it should always show vacuum when the car is at idle or cruise. It will only move over to no vacuum or boost when accelerating.

Has the car been driven on the street since the motor/turbo install?

 

you can drive around and it seems like you have no turbo.The boost comes on when the car is under load and more throttle