I have always noticed a difference in Boost Readings between my PFS Controller, Defi D-Gauge, and Profec B II Gauges.



When I hit 10PSI on the Profec B Screen, my D-Gauge reads around 9lbs



I have my PFS Controller set to cut the fuel at 13PSI......I have seen 13PSI PLENTY of times on the Profec B Spec II without feeling any fuel cut...I do have the fuel cut because I remember before the boost controller installation it would cut constantly due to the severe spiking



Which gauge should I tune the car too?



Please share your ideas on the accuracy of these gauges

 

I'm guessing you have the boost gauge tapped into the unused port on the intake manifold. So you are just seeing the pressure drop from the turbos to the intake manifold. Just a guess though

 

yes....but wouldnt the boost at the intake manifold be the most accurate reading for the boost "entering" the engine

 

Ok I read wrong. I thought you were asking why it reads different.



Yes you should tune the car to what boost level the engine is actually seeing. If you tune to what th eboost controller says the you will run rich. I don't think it is that much richer but I may be wrong.



I honestly have never tuned a car but i would think to tune it to what pressure the engine is seeing.

 

the easiest solution is to put all three on the same vac/boost source



my profec b II seems to be pretty accurate.....