Frost....MAP sensor question

[0rion]

I think I understand the map sensor linear table or at least the theory behind it. It's to scale your map sensor from 0-5v correct? So on 2 bar I see people using 200,207, and a couple other values but wouldn't it be 210 since that's where the ve maxes out on 2 bar?
What I don't understand is why there would be an offset and how to determine what your offset is? Is that key on/engine off scanner logging the map in kpa? I just assumed that would always be zero right, because the map should be reading zero there right?

[0rion]

nevermind...did some reading and have some of it figured out.

Offset is the 0 volt reading of your map sensor
and the linear is the 5v reading minus the offset.

What if you don't know these values? What do you use then?

[Frost]

If you don't know them, you figure out the offset... key-on with an OEM MAP and write down the value from the scanner. GO back to the 2bar MAP and adjust the offset until you read the same value at key-on.

Linear is the effective range of the sensor.

What is the part number that you have?

[0rion]

GM part number 12580698

[Frost]

offset = 8 (should get you very close)
linear = 200

That part number has now been superseded by 12615136.