Autoprom channels max out a 4 volts not 5

[96lt4c4]

I have always logged my wide band through my Autoprom. But, now since I have a turbo and a 2 BAR map that I can not use on my stock PCM, I figured I would at least use it log boost through one of the empty channels on my Autoprom. The max voltage the MAP puts out is about 4.75 VDC. So I connected a DC power supply to channel 2 on my Autoprom and used it to vary voltage and calibrate my boost gauge. I have it reading accurate but anything over 4 volts and the gauge will not go any higher. 4 volts comes out to 10 PSI Boost. I would like to be able to log higher than that, at least to the 4.75 the map puts out, which comes out to about 15 PSI. To make sure I tested the channel my wide band is on and its the same way.

Gauge is in Tuner Pro by the way

[96lt4c4]

Just realized i probably put this in the wrong section.