Manifold Pressure/Vacuum Sensor: Description and Operation

MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR




The MAP sensor voltage is converted by the ECM to a pressure kPa or psi). A high pressure (atmospheric pressure) produces an output of 4.5-5.0 V, about 95-105 kPa (14-15 psi). A low pressure (engine vacuum) produces about 0.5-0.9 V, about 37-50 kPa (5-7 psi). The MAP sensor is also used to calculate barometric pressure under certain conditions.

By monitoring the MAP sensor output voltage signal, the ECM determines the manifold pressure and can increase or decrease the injector on-time (or pulse width). The ECM also uses the MAP sensor signal to help control fuel, ignition timing, canister purge duty cycle and EGR operation.