Air Flow Sensor Plate Position Sensor: Adjustments

NOTE: Potentiometer is factory adjusted. Retaining screws are paint sealed.

TEST CONDITIONS
- sensor plate must be in rest position (1.9 ± 0.15 mm/0.074 ± 0.005 in.) below cone edge of venturi on fuel distributor side

POTENTIOMETER, CHECKING





- disconnect potentiometer





- unplug connector from potentiometer and connect test harness VW 1501 to potentiometer. Engine harness connector remains open









- connect digital multimeter US 1119 to terminals of test harness VW 1501 and check potentiometer resistance

If readings NOT OK
- replace potentiometer





- connect voltmeter between contact 1 and ground cable
- switch ON ignition
- specification: approximately 7.5 volts

If NO
- check for open circuit, using current flow diagram
- connect voltmeter between contact 1 and contact 3
- specification: approximately 7.5 volts

If NO
- check for open circuit, using current flow diagram
- switch OFF ignition





- connect ohmmeter between contact 2 of disconnected potentiometer connector and contact 17 of the control unit connector
- specification: approximately 0.0 ohms

If NO
- check for open circuit, using current flow diagram





- remove air shroud
- turn and lift adjusting screw 1 and slide 2 into upper (full throttle) position on VW 1348/1
- place VW 1348/1 centrally on edge of air flow sensor assembly pointer 3 faces to center of fuel distributor
- push adjusting slide 2 down onto stop
- turn setting screw 1 clockwise until magnetic end contacts air flow sensor plate retaining bolt (with air flow sensor plate in rest position)





- connect harness VW 1501 between potentiometer and terminal
- connect voltmeter to contacts 2 and 3 of harness
- switch ignition ON
- with sensor plate at rest position
- specification: approximately zero volts

If NO
- replace potentiometer





- pull slide 2 of adjusting device into the 1st detent (idle position)
- specification: 0.2 to 0.5 volts
- pull slide 2 of adjusting device into the 2nd detent (fill throttle position)
- specification: 4.0 to 4.5 volts

If NO
- replace potentiometer