Full Throttle Enrichment

Fig. 7 Differential Pressure Regulator Test Harness:

1. Before starting test, the engine should be warm (at least 70°C/158°F), and no faults stored in memory.
2. Connect test harness (VW 1315 A/1 or equivalent, Fig. 7) between the differential pressure regulator and the harness plug.
3. Remove harness plug from the coolant temperature sensor, and connect a 2.5K ohm resistance across the terminals (tool VW 1630 or equivalent).
4. As the engine is started, differential pressure regulator current should reach 15 - 23 mA in 6 to 9 seconds, then slowly drop to 9 - 11 mA.
5. Open the throttle completely, then release (being careful not to over rev the engine). Control current should increase to at least 6 mA.
6. If current readings are not within specification:
a. Check wiring between differential pressure regulator and injection control unit plug.
Red/Yellow wire to terminal 4
Red/White wire to terminal 5
b. Check wiring between coolant temperature sensor and injection control unit.
Black/Red wire to terminal 3
Brown/yellow wire to ground.
c. Check full throttle switch at the injection control unit plug between terminal 31 and ground.
1. With the throttle in the idle position, circuit should be open (infinite ohms).
2. With throttle completely open, resistance should be less than 0.2 ohms.
7. Repair wiring as necessary.
8. If wiring os OK, replace the injection control unit.