The most important information for measuring engine fuel requirements comes from the Manifold Absolute Pressure (MAP) sensor. Using the pressure and temperature data, the PCM calculates the intake air mass. It is connected to the engine intake manifold and takes readings of the absolute pressure.
Atmospheric pressure is measured both when the engine is started and when driving fully loaded, then the pressure sensor information is adjusted accordingly.
- Using a multimeter, check for voltage by backprobing the MAP sensor connector.
- With the key ON , and the engine OFF , verify that there is at least 4.8 volts between the SIG and GND terminals of the MAP sensor connector. If voltage is not within specification, check power and ground circuits and repair as necessary.
- With the key ON , and the engine ON , check the voltage between GND and SIG RTN terminals. Voltage should be approximately between 0.8 and 2.4 volts. If voltage is not within specification, the sensor may be faulty.
- If the voltage check in step 3 was OK , then check the voltage between GND and SIG RTN terminals and suddenly depress the accelerator, the voltage should rise and stay at 2.4 volts. If the voltage does not stay at 2.4 volts, replace the MAP sensor.
REMOVAL & INSTALLATION
- Disconnect the negative battery cable.
- Detach the connector for the MAP sensor.
- Remove the sensor mounting screws.
- Lift the sensor up and remove it from the intake manifold.
- The installation is the reverse of removal.