The MAF is measured by detection of heat transfer from a hot film probe because the change of the mass air flow rate causes change in the amount of heat being transferred from the hot film probe surface to the air flow. The air flow sensor generates a pulse so it repeatedly opens and closes between the voltages supplied from the PCM. This results in a change of the temperature of the hot film probe and in the change of resistance.
Removal & Installation
- Disconnect the negative battery cable.
- Disconnect the connector from the sensor.
- Remove the air cleaner and air intake assembly, as required.
- Remove the sensor from its mounting.
- Installation is the reverse of the removal procedure.
- Using a voltmeter check the sensor output voltage.
Specification should be as follows:
Intake air quantity 15 kg/h, output voltage 1.34 volts
- If not within specification, replace the sensor.
- If within specification, erase the DTC code. If code is reset replace the ECM with a known good component and recheck. Replace the ECM, as required.
- Connect the scan tool.
- Select -MAF SENSOR- parameter on the CURRENT DATA.
- Monitor the signal waveform of the -MAF SENSOR- on the scan tool.
- Specification, check that the value is increased correspondently with TPS when pressing the accelerator pedal.
- If not within specification substitute a known good sensor and recheck for proper operation. Replace defective components as required.
- If within specification, check the PCM as follows, ignition OFF. Connect the scan tool. Turn the ignition ON and engine OFF. Select simulation function on the scan tool. Simulate voltage at terminal 1 of the sensor connector.
- If the signal voltage value does not change, substitute a known good PCM and repeat the test. Replace the PCM as required. If the signal voltage value does change, check connectors for looseness, poor connection, binding etc. Correct and retest.