D21 Hardbody 4WD V6-2960cc 3.0L SOHC MFI (VG30E) (1991)
The "ALPHA" reading of CONSULT indicates if the fuel mixture is rich, lean, or correct.
Perform the following check to verify that a "Rich" condition exists.
With CONSULT plugged in and turned on with the engine at operating temperature and just above 2000 rpm:
The ALPHA reading should be in the range of 90% to 110%, if the fuel mixture is correct. One hundred percent indicates that no correction to the base
fuel schedule is necessary. Less than 100% indicates that the O2 sensor is detecting a rich condition and less fuel will be injected to correct for this. The
lower the ALPHA percentage the richer the mixture.
Note:
Obtaining a base line ALPHA reading at 2,000 rpm is necessary for verifying any repairs.
Mass Air Flow Sensor Test
Note:
The best way to resolve a Code 45 or driveability incident is to carefully go through ALL the steps contained within this bulletin.
A POOR CONNECTION FOR EITHER THE MAFS GROUND OR SIGNAL WIRE CAN CAUSE A FALSE HIGH MAFS VOLTAGE READING,
THIS WILL CAUSE A RICH MIXTURE.