Digital boost gage help

[Nuzzi]

I bought a digital boost gage a while back and just got around to installing it. The problem is it shows 5psi with the ign on, engine not running...at idle it shows about -6. Am I missing something or is this gage crap? The vacuum does increase in value when I give it throttle then let off (sitting in neutral, car isn't on the rd yet) I haven't revved it high enough to spool the turbo so cant tell if the boost side is working. The fact that it says +5 not running has me worried though. Anyone have the same problem?

heres an example of it

http://www.ebay.com/itm/2-52mm-PSI-...Parts_Accessories&hash=item23374bcc9c&vxp=mtr

 

[ThunderChild]

well, judging by the look of it, the gauge could be poo.

but, it also seems like you have a calibration issue. -6 vac is way too low. 15 in hg would be my mininum, and if you take your +5 when car is off and ign on (gauge should be zeroed at this point) you should be closer to proper level while running.

any directions come with the gauge to calibrate it? if not, pile of crap in my opinion.