The MAP sensor mounts to the intake manifold. The PCM supplies 5 volts direct current to the MAP sensor. The MAP sensor converts intake manifold pressure into voltage. The PCM monitors the MAP sensor output voltage. As vacuum increases MAP sensor voltage decreases proportionately. Also. as vacuum decreases, MAP sensor voltage increase proportionately.
At key on, before the engine is started, the PCM determines atmospheric air pressure from the MAP sensor voltage. While the engine operates, the PCM determines intake manifold pressure from the MAP sensor voltage. Based on MAP sensor voltage and inputs from other sensors, the PCM adjusts spark advance and the air/fuel mixture.Showing the MAP sensor location
If the PCM considers the MAP Sensor information inaccurate, the PCM moves into limp-in mode. When the MAP Sensor is in limp-in, the PCM limits the engine speed as a function of the Throttle Position Sensor (TPS) to between 1500 and 4000 rpm. If the MAP Sensor sends realistic signals once again, the PCM moves out of limp-in and resumes using the MAP values. During limp-in a DTC is set and the MIL illuminates.