boost gauge reading

[mazdaspeedGhali]

hey guys
I just installed a defi 30 psi boost gauge yesterday. I got it running but i had a few questions.

1. When the car is on and at idle the gauge reads 0, is that correct?
2. The car stays at 12 psi and before the bpv releases it shoots to 15. shouldnt it be at fifteen the whole time and "spike" to eighteen stock. (mods hypertech, pg tip, cobb sri, ********** rrm, stock cbe)
3. I hooked up the gauge to the vac line closet to the turbo. is that the correct one?

thanks for all the help

 

[boosted1]

1) At idle, the gauge should read at about 20-22 inch/Hg(vacuum). The only time the gauge reads '0', is when the car is turned off.
2) Does that happen in every gear?
3) I used a 3 way tee connected to the BPV small vac line. Your present hookup, doesn't appear to be giving you correct readings.

 

[spdjnke]

indeed, something is not connected correctly or you have a pinch in the line somewhere. normally you should get HGs, unless your running a straight boost gauge only without vacuum readings then 0 is correct cuz you have not hit positive boost pressure yet.

As for the "actual" boost pressure that varies from the brand of boost gauge some are more accurate then others, also at the time of the reading how much load is being put on the car...obv higher load = higher boost reading.