Powerlogger ecm reference volts

[turb0buick57]

Digging through the some old posts and my powerlogger, I noticed my ecm reference voltage is
4.94999981

I dont remember putting a value in there to begin with. I also noticed the 3 bar map is reading 1.48 KOEoff
while under hood the map signal wire is reading 1.56.
The 5 volt side of the map is 5.08 to the body ground.

What should the ecm reference volts be reading or what should I be changing it to?

Thanks

 

[TurboBob]

well, unless you have changed the wiring, the stock MAP sensor gets its power from the dash cluster (on the analog dash car). It gets its ground from the body of the car (somewhere).

So there will be differences in the 5v supply that the ECM uses for a reference (you can measure it at the PL analog block), and offsets in the ground. Most of the ECMs I have measured were 4.95 volts or so. That adjustment is there so you can match the ECM voltage.

If you are just logging boost, then the differences are small. If you are trying to run the car from the stock MAP setup (even with a 3 bar MAP), the offsets will make it idle funny and stumble when you hit the brakes....

I think you will be fine just leaving things as they are....

Bob