Air Flow Meter/Sensor: Testing and Inspection

CIRCUIT DIAGRAM





USING SCAN TOOL














HARNESS INSPECTION PROCEDURES

USING OSCILLOSCOPE

1. Run the engine at idle speed.





2. Connect the probe to the oscilloscope pick-up point as shown in the circuit diagram, and check the waveform.


TROUBLESHOOTING HINTS
1. If the engine stalls occasionally, start the engine and shake the Mass Air Flow (MAF) sensor harness. If the engine stalls, check for poor contact of the MAF sensor connector.
2. If the MAF sensor output Voltage is other than 0 when the ignition switch is turned on engine off), check for a faulty MAF sensor or Engine Control Module (ECM).
3. If the engine will idle even if the MAF sensor output Voltage is out of specification check for the following conditions;
- Disturbed air flow in the MAF sensor, disconnected air duct, clogged air cleaner filter.
- Poor combustion in the cylinders.
- Faulty spark plugs, ignition coil, injector, incorrect comparison.
- Vacuum leaks in the intake manifold.