I've got a quality boost gauge in my car (electronic defi) which tells me I'm at 17 psi. When logging with Cobb Accesstuner Race the MAP sensor is telling the ECU that it sees 21-22 psi. My boost reference source is a dedicated line from the intake manifold to my hallman. Anyone else seeing a discrepancy like this?
I see a bit of a discrepancy, although my Maddad boost gauge typically reads just slightly higher than my logs. Due to their nature, boost gauges do not take into account atmospheric pressure at all. Most quality ones allow calibration for your altitude, but atmospheric pressure does change regularly. Trust your MAP sensor. Assuming you are logging the correct parameter, it reads exactly what your boost pressure is in terms of PSI over current atmospheric pressure.
All lines are good, all connections are ziptied. I'll trust the MAP sensor, but it'll be interesting to see if the discrepancy shrinks when closer to sea level.
Do those DEFI's have a calibration button? If not (and it was calibrated at sea level), your altitude might explain your discrepancy.
Once the opening ceremony is done, the gauge reads 0/0 prior to starting the engine. Self calibrating, perhaps. I know that when I tried a couple of different pro-sport electronic gauges, they were crap at altitude. After the opening ceremony they read 7 in HG prior to starting the engine.
Most electric gauges read at 0 when the engine is off, though, and need an ignition on signal to do the startup sequence and read from the sensor. Might be worth checking out to see if there is any re-calibration sequence you can go through for the gauge.
Most, but definitely not the pro-sport parts. I'm able to find reference to calibration at power on time, but for the defi-link setups vs the standalone parts. Email is in to tech support regarding calibration.
