1985 Volkswagen Quantum Base, AutomaticFACTORY OEM SERVICE PROCEDURE

Airflow Sensor

  1. Remove rubber bellows above airflow sensor plate. Unplug electrical connectors on auxiliary air regulator and control pressure regulator. Operate fuel pump for 10 seconds to build up control pressure.
    Fig 1: Removing Fuel Distributor Control Plunger DO NOT allow control plunger to drop from fuel distributor.
    G35409
  2. Lift sensor plate slowly with magnet or pliers. Use care to avoid damage to sensor plate or venturi surfaces. Resistance due to control plunger pressure should be felt through entire lift. Release plate and allow it to return to rest position slowly. Lever and control plunger should follow. See Fig 2 .
  3. Lift plate and return it rapidly to rest position. Plunger should be heard hitting lever as it moves slowly to rest position. If not, control plunger is sticking. Remove 3 screws from fuel distributor and lift off of airflow sensor housing. Be careful not to drop control plunger. See Fig 1 .
    Fig 2: Checking Sensor Plate Operation & Adjustment
    G35410
  4. Clean plunger in gasoline. Remove any deposits with finger nail; DO NOT use tools. Slide plunger in and out while turning it. If any sticking or binding is felt, replace fuel distributor.
  5. Reinstall fuel distributor. Plate should be centered in housing. If not, loosen center bolt and align plate with 0.004" (.1 mm) feeler gauge at 4 points around rim. Using Loctite, install and tighten bolt.
  6. Check airflow sensor plate height adjustment. Plate should be even with bottom rim or 0.02" (0.5 mm) lower. If not, bend spring clip or reposition stop pin (tap lightly with punch) to set plate height. See Fig 2 .
Factory Service Tools

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.

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