Q: What does the Manifold Absolute Pressure (MAP) sensor measure?
A: The Manifold Absolute Pressure (MAP) sensor measures changes in intake manifold pressure, which is the difference between barometric pressure and manifold pressure. It helps the PCM adjust for different altitudes and controls fuel delivery and ignition timing. The PCM sends a 5 volt reference signal to the MAP sensor, and by monitoring the sensor output voltage, it can determine the manifold pressure. Testing involves comparing the voltage reading to a chart, backprobing the MAP connector, applying vacuum to the sensor, and checking the voltage between terminal C and ground. If the sensor and circuits are functional, the PCM may be faulty. To remove the MAP sensor, the intake manifold top cover is removed, the crankcase breather tube is disconnected, and the sensor is detached from the intake manifold. The MAP sensor grommet should be inspected and replaced if necessary. Installation is the reverse of the removal procedure.