Discussion and questions related to the course EFI Tuning Fundamentals
My question is regarding MAP Sensor Scaling, specifically Scalar and Offset. I understand that the Scalar is the multiplication conversion value from volts to pressure and the Offset is the literal offset of that conversion. But what I don't understand is why there is an Offset necessary. When the MAP sensor manufactured and they generate the Scalar, shouldn't the sensor be made so there is no offset?
It's typical for solid-state pressure sensors to use an offset of 0.5V or 1.0V What this does is allow you to determine when no sensor is connected and use a good default (instead of 0 pressure). ECUs can have a diagnostic High / Low voltages that trigger "sensor fault". For a 2 wire temp sensor with a built-in pull-up in the ECU -- a non-connected sensor will read whatever the reference voltage is, so you know it's disconnected.
I see, that makes perfect sense. Thank You