MAP offset and MAP scaler

Another day, another question for the gurus...

I swapped in my 2 bar and changed C6301 to make the reading output the same as my 1 bar was reading at KOEO...pretty easy.

Question is- it looks like the ecu applies the voltage from the MAP(A/D counts) into a linear formula using C6301 and 6302 to get the pressure in kPa.

Seems like each sensor should have it's own scaler (line slope) and offset(y-crossing).


If this is accurate- then why do we not change the offset? I was going to take a vacuum pump and check the MAP at another pressure less than atmospheric to validate this reasoning. Maybe if I set the scaler to 1 and offset to 0 and pull a couple different known pressures on the MAP, put in excel and linear fit to find the actual scaler and offset.

Seems reasonable?

You typically do need to change both the offset and scalar.
What sensor have you installed?

Yes, you could test with a known pressure to determine scalar and offset.

I used ACDELCO Part # 2131631.

From what I read- many people say to not change the offset. I will play around with it tonight.

Thanks!