Cold Acceleration Enrichment

To ensure smooth running, the injection system supplies additional fuel to the engine when cold, immediately after a cold start, or during full throttle operation by increasing differential pressure regulator current for a short period of time. The coolant temperature sensor provides the fuel injection control unit with the required engine temperature information needed for cold running enrichment. The throttle switch provides information concerning throttle position. The starter provides an additional signal to the control unit for after-start enrichment.

Diaphragm Pressure Regulator Testing Connections:

1. Connect an ammeter between the differential pressure regulator harness connector and the differential pressure regulator, using VOLKSWAGEN special tool #VW 1315A/1 or equivalent.

CAUTION: The small female terminals in the differential pressure regulator harness connector are easily damaged. If fabricating a test harness, use the appropriate male terminals to make connections with the harness connector.

Coolant Temperature Sensor:

2. Remove the harness connector from the coolant temperature sensor to simulate a cold engine.
3. Remove the intake air boot from the intake air sensor.
4. Turn the ignition switch "ON".
5. Open the throttle valve approx. 1/3.
6. With and appropriate device, lift the air flow sensor plate briefly.
7. Measure the differential pressure regulator current.

^ Differential Pressure Regulator current should rise momentarily to above 100 mA.

If the correct measurement is not obtained check the CIS-E harness. Refer to SYSTEM ELECTRICAL TESTS. If the harness is OK the CIS-E control unit may be defective.