Manifold Pressure/Vacuum Sensor: Description and Operation

PURPOSE
The Manifold Absolute Pressure (MAP) Sensor, which is mounted center of the firewall, sends a signal to the Programmed Fuel Injection Electronic Control Module (PGM-FI ECM). the PGM-FI ECM uses this signal to sense engine load. Ignition timing and fuel delivery can then be adjusted to maintain optimum engine performance.

OPERATION
The ECM supplies a 5 volt signal and a ground to the sensor. A vacuum line supplies intake manifold vacuum to a small cavity under the silicon diaphragm which causes the diaphragm to flex. The flexing of the silicon generates a small voltage which is amplified by the support circuitry and used to modify the fixed 5 volt signal supplied by the PGM-FI ECM. The modified signal is then returned to PGM-FI ECM.