Fuel Injectors, Checking Injection Quantity and for Leaks

Fuel Injectors, Checking Injection Quantity and for Leaks

Special tools, testers and auxiliary items required

• Remote control (VAG 1348/3A)

• Adapter cable (VAG 1348/3-2)

• Injection rate tester (VAG 1602)

• Connector test set (VAG 1594C)

• Test instrument adapter/DSO (5 pin) (VAS 5565)

Checking for Leaks

• Fuel pressure must be OK, checking fuel pressure. Refer to --> [ Fuel Pressure Regulator and Residual Pressure, Checking ] .

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





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

• Electrical connectors must be disconnected from the fuel injectors.

- Remove the rear seat bench.

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





- Disconnect the electrical connector - 1 -.





- Install the (VAS 5565) to the connector on the cover and on the fuel delivery unit.





- Connect the (VAG 1348/3A) to the (VAS 5565) and to positive (+) terminal on the battery.

- Operate the (VAG 1348/3A).

• This work 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 emit from each injector when the fuel pump is running.

If the fuel loss is greater:

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

• If fuel injectors were replaced, erase the adaptation values and adapt the Engine Control Module (ECM) again.

• Always use new seals.

Injection Quantity, Checking

• Fuel pressure must be OK, checking fuel pressure. Refer to --> [ Fuel Pressure Regulator and Residual Pressure, Checking ] .

• Fuel rail is removed.

• Fuel injectors installed in the fuel rail and fuel line connected.

• Fuel pump runs (connected to battery with adapter cables).

- Place a fuel injector to be tested into a graduated measuring glass from the (VAG 1602).

- Using adapter cables from the (VAG 1594 C), connect one terminal of the fuel injector to be checked to a known good ground.





- Connect the second terminal of the fuel injector with the adapter cable to the (VAG 1348/3 A) using the (VAG 1348/3-2).

- Connect the alligator clip to the battery positive (+) terminal.

- Operate the (VAG 1348/3A) for 30 seconds.

- Repeat the check on the other injectors. Use a new graduated measuring glass for each one.

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

Specified value: 85 to 105 ml per valve

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 ] .