Fuel Injectors, Leak and Injection Quantity, Checking
Fuel Injectors, Leak and Injection Quantity, Checking
Special tools, testers and auxiliary items required
• Remote Control (V.A.G 1348/3A)
• Adapter Cable (V.A.G 1348/3-2)
• Injector Rate Tester (V.A.G 1602)
• Connector Test Set (V.A.G 1594C)
=> [ Checking for Leaks ]
=> [ Injection Quantity, Checking ]
Checking for Leaks
The fuel system is under pressure! Wear protective goggles and protective clothing to prevent injuries and contact with skin. Before disconnecting the connection, wrap a cloth around the connection. Then carefully release pressure by disconnecting the connection.
• Fuel pressure must be OK, checking, refer to => [ Fuel Pressure Regulator and Residual Pressure, Checking ] Testing and Inspection.
Procedure
- Remove the intake manifold. Refer to => [ Intake Manifold ] Intake Manifold.
- Disconnect the connectors from the fuel injectors.
- Remove the fuel rail completely (fuel supply line remains connected) => [ Fuel Rail Overview ] Service and Repair.
- Remove the rear bench seat.
- Remove the cover - arrows - from the fuel delivery unit.
- First pull on the connector - arrow - without pressing the retainer to make sure it is securely connected. If the connector was not connected correctly, it could cause a fault.
- Disconnect the connector.
- Check the contacts on the connector and the fuel delivery unit for damage.
- Install the (VAS 5565) between the connectors on the fuel delivery unit and cover.
- Connect the (V.A.G 1348/3A) to the (VAS 5565) and to the battery positive terminal.
• This work step allows the fuel pump to run when the engine is not running.
- Check injectors for leaks (visual inspection).
• Only 1 to 2 drops per minute may emit from each valve when fuel pump is running.
If the fuel loss is greater:
- Replace any leaking fuel injectors. Refer to => [ Fuel Rail Overview ] Service and Repair.
Perform the installation of injectors in reverse order. When doing this note the following:
• Replace O-rings on all injectors and lightly lubricate with clean engine oil.
• Install fuel injectors into the fuel rail perpendicular and in the correct position, and secure them with the retaining clips.
• Position the fuel rail with secured fuel injectors onto the cylinder head and apply uniform pressure to press it in.
• If fuel injectors are replaced, erase adaptation values and adapt Engine Control Module (ECM) again. Refer to "Guided Functions" in the vehicle diagnostic tester.
Injection Quantity, Checking
• Fuel pressure must be OK, checking, refer to => [ Fuel Pressure Regulator and Residual Pressure, Checking ] Testing and Inspection.
• Intake manifold is removed.
• Fuel injectors are installed in the fuel rail and the fuel line connected.
Procedure
- Place a fuel injector to be tested into a graduated measuring glass from the (V.A.G 1602).
- Remove the rear bench seat.
- Remove the cover from the fuel delivery unit.
- First pull on the connector - arrow - without pressing the retainer to make sure it is securely connected. If the connector was not connected correctly, it could cause a fault.
- Disconnect the connector.
- Check the contacts on the connector and the fuel delivery unit for damage.
- install the (VAS 5565) between the connectors on the fuel delivery unit and cover.
- Connect the (V.A.G 1348/3A) to the (VAS 5565) and to the battery positive terminal.
• This step allows the fuel pump to run when the engine is not running.
- Using adapter cables from (V.A.G 1594 C) , connect one terminal of the fuel injector to be checked to engine Ground (GND).
- Connect the second fuel injector terminal using (V.A.G 1348/3 - 2) to the (V.A.G 1348/3A).
- Connect the alligator clip to the battery positive terminal (positive terminal in the engine compartment).
- Operate the (V.A.G 1348/3A) for 30 seconds.
- Repeat check on the other injectors. Use new graduated measuring glasses for this.
- After all the fuel injectors have been activated, place the graduated measuring glasses on a level surface and compare quantity of injected fuel.
• Specified value: 128 to 140 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 Rail Overview ] Service and Repair.
Perform installation of injectors in reverse order. When doing this note the following:
• Replace O-rings on all injectors and lightly lubricate with clean engine oil.
• Insert fuel injectors into fuel rail perpendicular and in the correct position, and secure them with retaining clips.
• Position fuel distributor with secured fuel injectors onto the cylinder head and apply uniform pressure to press it in.
• If the fuel injectors are replaced, erase adaptation values and adapt the Engine Control Module (ECM) again. Refer to "Guided Functions" in the vehicle diagnostic tester.