Manifold Pressure/Vacuum Sensor: Description and Operation

Manifold Absolute Pressure (MAP) Sensor
The Manifold Absolute Pressure (MAP) sensor responds to any changes in the intake manifold pressure. The pressure any changes as a result of the engine load and speed. The MAP sensor converts this to a voltage output.

A closed throttle on the engine coast down would produce a relatively low MAP output voltage. A wide open throttle would produce a high MAP output voltage. This high output voltage is produced because the pressure inside of the manifold is the same as outside the manifold. The MAP is inversely proportional to what is measured on a vacuum gage. The MAP sensor is used for the following:
- Altitude determination.
- Ignition timing control.
- EGR diagnostic.
- Speed density fuel management default.