Check Triggering Of Fuel Injectors

The fuel injectors can be individually suppressed with the Porsche System Tester 2 in the menu "Drive Link Active". The engine idle speed decreases if triggering is OK.

If no drop in RPM can be detected, check triggering as follows:

1. a) B+ suppl
   
   Remove connector of fuel injector to be checked.
2. Connect voltmeter to the valve plug contact, terminal 1, and ground using an auxiliary cable.
3. Remove complete air filter system.
4. Switch on the ignition. Display: battery voltage

If meter does not read battery voltage, check wiring according to wiring diagram for continuity or short circuit.

1. b) Coil resistance of fuel injectors
   
   Remove connector of fuel injector to be checked.
2. With an ohmmeter, measure resistance between terminals of fuel injector. Display: 11-13 ohms.

1. c) Injection output stage (negative supply)
   
   Connect special tool V.A.G. 1315 A/1 between fuel injector and connector.
2. Connect engine tester according to manufacturer's instructions. Connect cable for special input to special too.
   CAUTION: Tester cable must not be connected to ground.
3. Start the engine. For a perfectly working injector output stage, the following display must be shown at starting RPM.
   Fig 1: Identifying Ideal Fuel Injector Output Stage Display

   Courtesy of PORSCHE OF NORTH AMERICA, INC.
   NOTE: If the engine does not start, or if the idling speed drops, replace tester cable connected to special tool.