Volkswagen Front Wheel Drive 1974-1989 Repair Guide

Airflow Sensor

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REMOVAL & INSTALLATION



  1. Disconnect the negative battery cable.
  2.  
  3. Remove the air intake boot from the top of the airflow sensor.
  4.  
  5. Remove the fuel distributor.
  6.  
  7. Remove the screws securing the airflow sensor to the air filter housing, then remove the sensor assembly.
  8.  

To install:
  1. Position the airflow sensor on top of the air filter housing with a new gasket. Tighten the screws until snug.
  2.  
  3. Install the fuel distributor with a new gasket.
  4.  
  5. Install the air intake boot on the sensor assembly. If the sensor assembly is equipped with a protective screen, make sure the dome points upwards towards the air intake boot, not towards the sensor plate.
  6.  
  7. Connect the battery cable.
  8.  

TESTING & ADJUSTMENT



See Figures 1 and 2

For the sensor plate lever basic adjustment procedure, refer to thefuel distributor adjustment procedures.This adjustment should be checked anytime the fuel distributor or airflow sensor is replaced.

  1. On vehicles without electronic ignition, unplug the center wire from the distributor and ground it. On models with electronic ignition, unplug the connector from the Hall sending unit on the distributor. This will disable the ignition system.
  2.  
  3. Remove the air intake boot from the sensor assembly.
  4.  
  5. Crank the engine for about 10 seconds. This will pressurize the fuel system.
  6.  

The sensor plate must be centered in the air cone. If it is not, loosen the centering bolt slightly, then run a 0.004 in. (0.10mm) feeler gauge around the perimeter of the air gap (between the sensor plate and air cone). Retighten the bolt.

  1. Lift the sensor plate with a magnet. Over its entire travel, an even resistance should be felt. Move the sensor plate quickly from the raised position to its rest. No resistance should be felt. If resistance is felt, the airflow sensor must be replaced. If the plate is hard to move upwards, but moves freely downwards, the control plunger in the fuel distributor is sticking. Replace the fuel distributor.
  2.  



Click image to see an enlarged view

Fig. Fig. 1: A magnet can be used to lift the sensor plate

  1. Install the air intake boot.
  2.  
  3. Enable the ignition system, then run the engine to normal operating temperature.
  4.  
  5. Once again, disable the ignition system, then operate the starter for 10 seconds. Remove the air intake boot from the sensor assembly.
  6.  
  7. Check the sensor plate rest position. The upper edge of the sensor plate must be flush with the edge of the air cone.
  8.  



Click image to see an enlarged view

Fig. Fig. 2: The plate may be lower than the upper edge of the air cone, but not more than 0.019 in. (0.5mm)

  1. If it is too high, adjust the air sensor plate position. The plate may be lower than the upper edge of the air cone, but not more than 0.019 in. (0.5 mm). To adjust the sensor plate:
    1. Carefully lift the sensor plate.
    2.  
    3. Adjust the plate by bending the wire, NOT the small leaf spring.
    4.  

  2.  
  3. Install the air intake boot and enable the ignition system.
  4.  
  5. Adjust the idle speed.
  6.  

 
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