As the title suggests, MSPNP PRO is reporting 13.2V in Tunerstudio but when measured with a DMM I see 14.6V. Fresh WestCo battery and high amp alternator.

ECU ground bad?
Calibrate battery voltage in TS?

 

Where are you checking the voltage with the DMM at? I would check it across +12 and GND at the ECU header and see if there is a discrepancy between there and the ECU readings and go from there.

 

a running engine typically outputs 14.4v or so, to charge the battery

 

Just wondering why such a discrepancy. I upgraded from ms2, when the voltage used to be accurate.

measured across posts

 

Best way to probe the wire while its connected?

 

That is how I would measure it, have TS open showing the voltage that the MS sees and the DMM beside it to compare. If there's a discrepancy then there is likely (Disclaimer: I only know enough to know I don't know enough when it comes to electrical, so I might be wrong here) something going on with the MS, if they match up there, then I would start checking grounds, as unreliable grounds (read high resistance) may be causing the voltage drop to the ECU.

Maybe someone else can chime in and confirm or deny if I'm full of it

 

Tunerstudio has a calibrate battery voltage tool that I have never touched. I got the MS second hand and it has been running great, just a lil OCD about discrepancies. I want to start there before I start taking things physically apart when there is no issue with driveability

 

MS should be calibrated to represent the voltage at the injector, or possibly at the alternator for NB applications.

I personally prefer the injector as long as the alternator voltage at high load is still reasonable.

 

Sounds like Battery Voltage should be labeled Injector Voltage