rossman

I just installed a 30lb boost guage, what is it supposed to read when engine is off???
Thanks
-R

D4u2s0t

it will probably read vacuum.

lsjwannabe

iTrader: (1)

If the car is off usually it would read in vacuum because that is where it is at. Thats what mine used to do until i turned the key to the on poisition.

Omega_5

It depends on the gauge type.

Electrical gauges will either have a set 'off' point.... the factory gauge simply remains at the last position it was in.

Mechanical gauges, however, will (usually) read at all times, so when the car is off, it will be reading atmospheric pressure.... on a boost gauge that will be '0' psig (notice that's 'gauge' psi, not absolute).
Also, depending on what your gauge's reference is, that might change with respect to altitude as well.

rossman

Cool thanks guys

theneelster

ZERO or it's bunk. I own a mechanical gauge. That's what I know.

rossman

Will a 30 boost guage from a 08 work in a 06??