Fuel Injector: Testing and Inspection

Fuel Injectors, Checking

Special tools, testers and auxiliary items required

• Remote Control (V.A.G 1348/3A)

• Adapter Lead (V.A.G 1348/3-2)

• Injection Rate Tester (V.A.G 1602)

• Connector Test Set (V.A.G 1594 C)

• Test Instrument Adapter/DSO (5-pin) (VAS 5565)

• Follow all safety precautions. Refer to => [ Safety Precautions ] Safety Precautions.

• Pay attention to the rules of cleanliness. Refer to => [ Clean Working Conditions ] Clean Working Conditions.

Checking for Leaks:

• The fuel system must be OK. Checking.

The fuel system is under pressure!

• Always wear protective eyewear and protective clothing to prevent injuries and fuel from coming in contact with your skin.

• Before loosening line connections, place a cloth around the connection point. Then release pressure by carefully disconnecting the line.

- Remove the fuel rail - 2 - with the fuel injectors installed. Refer to => [ Fuel Injectors ] Fuel Injectors and place it on a clean cloth.






Do not disconnect the battery and do not disconnect the fuel supply line quick coupling at the fuel rail.

• The harness connectors must be disconnected from the fuel injectors.

- Remove the rear bench seat.

- Unclip the cover - 1 - from the fuel delivery unit. The arrow - 2 - points in the direction of travel.






- First, pull on the connector - arrow - without pressing the retainer to make sure it is connected securely. If the connector was not connected correctly, it could cause a fault.






- Disconnect the connector - arrow -.

- Check the contacts on the connector and the fuel delivery unit for damage.

- Install the test instrument adapter/DSO (5-pin) (VAS 5565) between the connectors on the fuel delivery unit and cover.






- Connect the remote control (V.A.G 1348/3A) to the test instrument adapter/DSO (5-pin) (VAS 5565) and to the battery positive (+).

- Operate the remote control (V.A.G 1348/3A).

• This step allows the fuel pump to run when the engine is not running.

- Check the injectors for leaks (visual inspection).

• Only 1 to 2 drops per minute may drip from each injector when the fuel pump is running.

If the fuel loss is greater:

- Disconnect the connection to the battery positive (+) and replace the leaking fuel injector. Refer to => [ Fuel Injectors ] Fuel Injectors.

• If the fuel injectors are replaced, erase the adaptation values and adapt the Engine Control Module (ECM) again. Refer to "Guided Functions" in the vehicle diagnostic tester.

• Always use new seals.

Injection Quantity, Checking

• The fuel system must be OK. Checking, refer to => Fuel Supply System 20.

• The fuel rail is removed.

• The fuel injectors are installed in the fuel rail and the fuel line is connected.

• The fuel pump runs (connected to the battery with adapter cables).

- Place a fuel injector to be tested into a graduated measuring glass from the injection rate tester (V.A.G 1602).

- Using adapter cables from the connector test kit (V.A.G 1594 C) , connect one terminal of the fuel injector to be checked to engine ground (GND).






- Connect the second terminal of the fuel injector to the remote control (V.A.G 1348/3 A) using adapter cable (V.A.G 1348/3-2).

- Connect the alligator clip to B+.

- Operate the remote control (V.A.G 1348/3A) for 30 seconds.

- Repeat the check on the other injectors. Use new graduated measuring glasses for this.

- After all fuel injectors have been activated, place the graduated measuring glasses on a level surface and compare the quantity of injected fuel.

• Specified value: 85 to 105 ml per injector

While checking the injection quantity, the spray pattern should also be checked. Spray pattern must be the same for all fuel injectors.

If the measured value of one or more fuel injectors is below or above the indicated specified value:

- Replace the faulty fuel injector. Refer to => [ Fuel Injectors ] Fuel Injectors.