Manifold Pressure/Vacuum Sensor: Description and Operation

MAP Sensor:

The Manifold Absolute Pressure (MAP) sensor measures changes in the intake manifold pressure resulting from engine load and speed changes and converts this to a voltage output, Fig. 7.

The ECM sends a 5 volt reference signal to the MAP sensor. As pressure changes in the intake manifold occur, the electrical resistance of the MAP sensor also changes. By monitoring the sensor output voltage, the ECM can determine the MAP. The higher the MAP, the lower the engine vacuum and the higher the sensor output, which requires more fuel. The lower the MAP, the higher the engine vacuum and the lower the sensor output, which requires less fuel.