Manifold Pressure/Vacuum Sensor: Description and Operation

The MAP sensor is located in the intake manifold on both SOHC and DOHC 1.9 L engines. The MAP sensor is a transducer that varies resistance according to changes in intake manifold pressure (vacuum). The PCM measures the signal voltage from the MAP sensor, which is a reduced value of the PCM 5 volt reference. The voltage ranges from 1 - 1.5 volts at idle (low pressure/high vacuum) to 4 - 4.5 volts at wide open throttle (high pressure/low vacuum).

The MAP sensor is primarily used for fuel control. Low intake manifold pressure indicates low engine RPM or low engine load. The higher the pressure in the intake manifold, the greater the load on the engine. The MAP sensor is also used for ignition timing, EVAP purge solenoid duty cycle, EGR operation and EGR flow diagnostics.