Manifold Pressure/Vacuum Sensor: Description and Operation

MAP Sensor:

The Manifold Absolute Pressure (MAP) Sensor reads pressure changes in the intake manifold with reference to zero or absolute vacuum. These changes are converted to electrical signals that can be interpreted by the ECM. This sensor also provides the ECM with atmospheric pressure information which is used to calculate air/fuel ratio adjustments at high altitudes. To alternate between intake manifold pressure and atmospheric pressure, the system utilizes an ECM controlled vacuum switching valve.