MAP offset and MAP scaler

[RADustin]

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?

[darcy]

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.

[RADustin]

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!