Mazda Trucks 1994-1998 Repair Guide

Volume Air Flow Sensor

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Only 1994-95 MPV models equipped with the 3.0L engine utilize a volume air flow sensor.

OPERATION



The volume air flow sensor directly measures the amount of the air flowing into the engine. The sensor is mounted between the air cleaner assembly and the air cleaner outlet tube.

The sensor utilizes a shutter valve that measures the amount of air entering the engine. The sensor does this by sending a signal, generated by the sensor as the shutter opens and closes, to the PCM. The signal is used by the PCM to calculate the injector pulse width, which controls the air/fuel ratio in the engine. The sensor and plastic housing are integral and must be replaced if found to be defective.

The volume air flow sensor also contains an intake air temperature sensor and fuel pump switch.

TESTING



See Figures 1 through 7

Testing of the volume air flow sensor also includes testing of the integral intake air temperature sensor.



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Fig. Fig. 1: Displaying how to open and close the shutter with finger when testing the volume airflow sensor



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Fig. Fig. 2: Checking the resistance of the volume airflow sensor with the shutter closed



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Fig. Fig. 3: Checking the resistance of the volume airflow sensor while moving the shutter



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Fig. Fig. 4: Using a voltmeter with a temperature probe (A), an ohmmeter (B) and a hairdryer (C), measure the resistance fluctuation of the integral intake air temperature sensor



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Fig. Fig. 5: Checking the resistance of the intake air temp sensor

  1. Remove the volume air flow sensor from the vehicle.
  2.  
  3. Inspect the volume air flow sensor for cracks or any other signs of damage.
  4.  
  5. Check that the sensor shutter plate opens and closes smoothly.
  6.  



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Fig. Fig. 6: Volume air flow sensor terminal identifications



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Fig. Fig. 7: Resistance specifications for the volume air flow sensor

  1. Using an ohmmeter, open and close the sensor shutter plate while checking the resistance between the terminals.
  2.  
  3. Using a voltmeter with a temperature probe, an ohmmeter and a hairdryer for temperature variation, measure the resistance fluctuation of the integral intake air temperature sensor.
  4.  
  5. If the resistance does not measure within specifications, replace the volume air flow sensor.
  6.  

REMOVAL & INSTALLATION



See Figures 8 through 14



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Fig. Fig. 8: Loosen the air inlet duct hose clamp at the volume airflow sensor



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Fig. Fig. 9: Release the metal volume airflow sensor connector retaining clip using a small tool such as a pick ...



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Fig. Fig. 10: ... then pull the connector straight off of the sensor



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Fig. Fig. 11: Loosen the five air cleaner housing cover fasteners and remove from the vehicle



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Fig. Fig. 12: The volume airflow sensor is secured to the top of the air cleaner housing cover with four mounting nuts and one mounting bolt



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Fig. Fig. 13: After removing the four mounting nuts, remove the inner mounting plate



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Fig. Fig. 14: After removing the mounting bolt, the volume airflow sensor can now be separated from the air cleaner housing cover

  1. Disconnect the negative battery cable.
  2.  
  3. Loosen the air inlet duct hose clamp at the volume airflow sensor.
  4.  
  5. Release the metal volume airflow sensor connector retaining clip using a small tool such as a pick and pull the connector straight off of the sensor.
  6.  
  7. Loosen the five air cleaner housing cover fasteners and remove from the vehicle.
  8.  
  9. Remove the four mounting nuts, then remove the inner mounting plate.
  10.  
  11. After removing the mounting bolt, separate the volume airflow sensor from the air cleaner housing cover
  12.  

To install:
  1. Install the volume air flow sensor to the air cleaner housing cover and tighten the mounting bolt.
  2.  
  3. Install the inner mounting plate and tighten the 4 mounting bolts.
  4.  
  5. Place the air cleaner housing cover and air flow sensor on top of the air cleaner box.
  6.  
  7. Connect the air inlet hose duct to the air flow sensor and tighten the hose clamp.
  8.  
  9. Attach the engine wiring harness connector to the volume air flow sensor and tighten down the air cleaner housing cover fasteners.
  10.  
  11. Connect the negative battery cable.
  12.  

 
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