The absolute pressure sensor in the intake manifold is a variable resistor sensitive to pressure changes. It measures the pressure in the intake manifold, which changes depending on the operating modes of the engine and is converted into an output signal voltage. The sensor is also used to measure atmospheric pressure when starting the engine and provides engine operating modes at different altitudes above sea level. The sensor is powered by 5 V. Based on the information from the sensor, the engine control unit regulates the amount of fuel supplied to the engine and changes the ignition timing.
Examination
1. Connect a voltmeter between terminals 1 and 4 of the MAP sensor connector:
- Contact 4: "Mass"
- Pin 1: Absolute pressure sensor output
Output voltage with ignition on and engine not running: 4–5 V
Output voltage at idle frequency: 1.14±0.4 V
2. If the sensor output voltage is different from the required one, replace the sensor.