Grand AM L4-138 2.3L DOHC VIN D MFI (1994)
Manifold Pressure/Vacuum Sensor: Description and Operation
MAP Sensor.
Map Sensor Circuit (GM Generic)
PURPOSE
The Manifold Absolute Pressure (MAP) sensor measures changes in the intake manifold pressure resulting from engine load and speed changes.
Under certain conditions, the MAP sensor is also used to measure barometric pressure. This allows the computer to automatically adjust for different
altitudes. The computer uses the MAP sensor to control fuel delivery and ignition timing.
LOCATION
Top of intake manifold.
OPERATION
The computer sends a 5.0 volt reference signal to the MAP sensor. As pressure changes in the intake manifold occur, the electrical resistance of the
MAP sensor also changes. By monitoring the sensor output voltage, the computer can determine the manifold absolute pressure. The higher the MAP
voltage output the lower the engine vacuum, which requires more fuel. The lower the MAP voltage output the higher the engine vacuum, which
requires less fuel.