Manifold Pressure/Vacuum Sensor: Description and Operation

MAP Sensor:

DESCRIPTION
The Manifold Absolute Pressure (MAP) sensor is mounted on top of the intake manifold and measures the changes in intake manifold pressure which result from engine speed and load changes. The PCM supplies a 5 volt reference signal and a ground to the sensor and the sensor outputs another voltage signal that is proportional to the pressure signal.

OPERATION
A high pressure (low vacuum) will produce a signal close to 5 volts and a low pressure (high vacuum) will produce a signal under one volt. The PCM scales the MAP sensor signal in kilo-Pascals (kPa). The MAP signal is the Inverse of what is read on a vacuum gage. When the MAP value is high, intake vacuum with a vacuum gage will be low.

PCM INPUT
The PCM uses MAP information for EGR control and diagnostics. MAP information is also used to determine barometric pressure and for ignition control. A faulty MAP sensor may cause various driveability conditions and should set a Diagnostic Trouble Code (DTC).