Air Flow Meter/Sensor: Testing and Inspection

DESCRIPTION
The mass air flow sensor is placed in the stream of intake air. It measures the intake flow rate by measuring a part of the entire intake flow. It consists of a hot film resistor that is supplied with electric current from the ECM. The temperature of the hot film resistor is controlled by the ECM a certain amount. The heat generated by the hot film resistor is reduced as the intake air flows around it. The more air, the greater the heat loss.
Therefore, the ECM must supply more electric current to maintain the temperature of the hot film resistor as air flow increases. The ECM detects the air flow by means of this current change.




DIAGNOSTIC TROUBLE CODE CONFIRMATION PROCEDURE
Procedure for malfunction A
WITH CONSULT
1. Turn ignition switch "ON", and wait at least 6 seconds.
2. Select "DATA MONITOR" mode with CONSULT.
3. Start engine and wait at least 3 seconds.

OR

WITH GST
1. Turn ignition switch "ON", and wait at least 6 seconds.
2. Start engine and wait at least 3 seconds.
3. Select "MODE 3" with GST.

OR

WITH NO TOOLS
1. Turn ignition switch "ON", and wait at least 6 seconds.
2. Start engine and wait at least 3 seconds.
3. Turn ignition switch "OFF", wait at least 5 seconds and then turn "ON".
4. Perform diagnostic test mode II (Self-diagnostic results) with ECM.

Procedure for malfunction B
WITH CONSULT
1. Turn ignition switch "ON".
2. Select "DATA MONITOR" mode with CONSULT.
3. Start engine and warm it up sufficiently.
4. Run engine for at least 10 seconds at idle speed.

OR

WITH GST
1. Turn ignition switch "ON".
2. Start engine and warm it up sufficiently.
3. Run engine for at least 10 seconds at idle speed.
4. Select "MODE 3" with GST

OR

WITH NO TOOLS
1. Turn ignition switch "ON".
2. Start engine and warm it up sufficiently.
3. Run engine for at least 10 seconds at idle speed.
4. Turn ignition switch "OFF", wait at least 5 seconds and then turn "ON".
5. Perform diagnostic test mode II (Self-diagnostic results) with ECM.

OVERALL FUNCTION CHECK
Use this procedure to check the overall function of the mass air flow sensor circuit. During this check, a DTC might not be confirmed.

Procedure for malfunction C
WITH CONSULT
1. Turn ignition switch "ON".
2. Start engine and warm it up sufficiently.
3. Select "DATA MONITOR" mode with CONSULT.




4. Check the voltage of mass air flow sensor with "DATA MONITOR".
5. Check for linear voltage rise in response to increases to about 4000 rpm in engine speed.

OR

WITH GST
1. Turn ignition switch "ON".
2. Start engine and warm it up sufficiently.




3. Select "MODE 1" with GST.
4. Check the mass air flow with "MODE 1".
5. Check for linear mass air flow rise in response to increases to about 4,000 rpm in engine speed.

OR

WITH NO TOOLS
1. Turn ignition switch "ON".
2. Start engine and warm it up sufficiently.




3. Check the voltage between ECM terminal (47) and ground.
4. Check for linear voltage rise in response to increases to about 4,000 rpm in engine speed.




WIRING DIAGRAM




DIAGNOSTIC PROCEDURE

COMPONENT INSPECTION
1. Turn ignition switch "ON".
2. Start engine and warm it up sufficiently.




3. Check voltage between terminal (4) and ground.




*: Check for linear voltage rise in response to increases to about 4,000 rpm in engine speed.




4. If NG, remove mass air flow sensor from air duct. Check hot film for damage or dust.