Manifold Absolute Pressure (MAP) Sensor

MAP sensor responds to manifold vacuum changes due to engine load and speed changes. Manifold pressure and temperature are used to calculate the airflow rate to the PCM.

The MAP sensor uses frequency to measure manifold vacuum. Map sensor frequency increases as vacuum increases. The MAP sensor is used as a barometric sensor for altitude compensation, updating the PCM during Key On, Engine Off (KOEO) and at Wide Open Throttle (WOT). By monitoring MAP sensor output voltage, the PCM can determine correct rate of spark advance, EGR flow and air/fuel ratio. If MAP sensor fails, the PCM will supply a fixed MAP value and use the Throttle Position (TP) sensor to control fuel distribution.