Acceleration Enrichment
Requirements:^ engine temperature maximum 30°C (86°F)
^ differential pressure regulator OK
NOTE: To perform this check the control unit is looking for a temperature signal, lower than 30°C (86°F). If the engine is warmer than 30°C (86°F), disconnect the temperature sensor and substitute a cooled down sensor which is grounded with a jumper wire.
- connect multimeter US 1119 to differential pressure regulator, using adaptor VW 1315 A/1
- disconnect oxygen sensor harness connector (arrow)
- run engine at idle
^ specification: 1 to 3mA
It specification is NOT obtained
- check coolant temperature sensor
- depress accelerator pedal briefly
^ specification: differential pressure regulator current must increase to a minimum of 6mA
NOTE: As RPM increases, differential pressure regulator current must also increase. If this current increases only when RPMs drop, check the operation of the air flow sensor potentiometer.
If specification is NOT obtained
- shut off engine
- disconnect coolant temperature sensor harness connector (arrow)
- connect multimeter US 1119 between sensor terminal 1 and engine ground, take reading
- repeat between sensor terminal 2 and engine ground, take reading
^ specification: greater than 1 k ohm
If a specification greater than 1 kohm is NOT obtained [at a coolant temperature of approximately 30°C (86°F)
- replace coolant temperature sensor
- repeat check
If specification IS obtained
Coolant Temperature Sensor, Harness Connector:
- remove harness connector from coolant temperature sender
- connect multimeter US 1119 between terminal 1 of the harness connector and engine ground
- switch ignition ON
^ specification: 4.5 - 5.5 volts
- repeat between terminal 2 and engine ground (specification: same)
If this, or one of the other specifications is NOT obtained
- repair break in wiring between the control units and the connectors, using the wiring diagram
If specification is NOT obtained and no break in wiring is found
- replace respective control unit