The intake manifold absolute pressure sensor is a pressure sensitive variable resistor. It measures intake manifold pressure, which varies with engine operating conditions and is converted into an output signal voltage. The sensor is also used to measure atmospheric pressure when starting the engine and provides engine operation modes at different altitudes. The sensor is powered by a voltage of 5 V. Based on information from the sensor, the engine control unit regulates the amount of fuel supplied to the engine, and also changes the ignition timing.
Examination
1. Connect a voltmeter between terminals 1 and 4 of the MAP sensor connector:
- Pin 4: «Weight»
- Pin 1: Absolute pressure sensor output
Output voltage with the ignition on and the engine off: 4-5 V
Output voltage at idle frequency: 1.14±0.4V
2. If the output voltage of the sensor is not as specified, replace the sensor.