Re: MAP sensor
The MANIFOLD ADSOLUTE PRESSURE .MAP. - sensor measures the changes in the intake manifold pressure which result from engine load- intake manifold vacuum.-and rpm changes, and converts these into voltage output. By monitoring the sensor output voltage, the ECM knows the the manifold pressure. At lower pressure output voltage will be about 1 to 2 volts at idle.
While at higher pressure or Wide Open Throttle -WOT - output voltage will be about 4 to 4.8. The MAP sensor is also used under certain conditions to measure barometric pressure allowing the ECM to make adjustments for different altitudes. The ECM uses the MAP sensor to control fuel delivery and ignition timing.
I hope that helps