Manifold Absolute Pressure (MAP) Sensor

MAP sensor is mounted on engine compartment firewall. The MAP sensor is used by PCM to calibrate amount of air/fuel mixture supplied to the engine. This sensor measures manifold absolute pressure. Ambient barometric pressure is also measured when ignition switch is first turned on, during engine cranking, and at wide open throttle.

The MAP sensor transmits a low voltage signal (1.5-2.1 volts) at idle when manifold vacuum is high, and a higher voltage signal (3.9-4.8 volts) during open throttle when manifold vacuum is low.

Input voltage (from the PCM) to MAP sensor ranges from 4.8-5.1 volts. Adjustments made as a result of this input will usually affect injector pulse width, ignition timing, idle speed and upshift indicator light.