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)
=> [ Checking for Leaks ]
=> [ Injection Quantity, Checking ]
Checking for Leaks
CAUTION!
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 release the pressure by carefully 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 fuel injector electrical connectors.
- Remove the fuel rail completely (fuel supply line remains connected). Refer to => [ Fuel Rail Assembly Overview ] Service and Repair.
- Remove fuse SB6 in position F6 in the fuse holder. Fuse assignment, refer to.
- Connect the left terminal (in direction of vehicle travel) of fuse socket and battery positive terminal with adapter from the (VAG 1594C ) so that the fuel pump runs.
• This 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 leak from each injector when the fuel pump is running.
If the fuel loss is greater:
- Disconnect the connection between the fuse socket and battery positive and replace the leaking fuel injector. Refer to => [ Fuel Rail Assembly Overview ] Service and Repair.
Perform the installation of the injectors in reverse order. When doing this note the following:
• Replace the O-rings on all injectors and lightly lubricate them with clean engine oil.
• Install the 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 a uniform pressure to press it in.
• If fuel injectors are replaced, erase adaptation values and adapt the Engine Control Module (ECM) again. Refer to "Guided Functions".
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 installed in fuel rail and fuel line connected.
Procedure
- Place a fuel injector to be tested into a graduated measuring glass such as (VAG 1602).
- Remove fuse SB6 in position F6 in the fuse holder. Fuse assignment, refer to.
- Connect the left terminal (in direction of vehicle travel) of the fuse socket and the battery positive terminal with adapter from ( VAG 1594C) so that the fuel pump runs.
• This step allows the fuel pump to run when the engine is not running.
- Using adapter cables from the (VAG 1594C), connect one terminal of the fuel injector to be checked to a engine ground.
- Connect the second fuel injector terminal with adapter cable to the (VAG 1348/3A) using the (VAG 1348/3-2).
- Connect the alligator clip to battery the battery positive, (positive terminal in the engine compartment).
- Operate the (VAG 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: 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:
- Disconnect the connection between the fuse socket and battery positive and replace the faulty fuel injector. Refer to => [ Fuel Rail Assembly Overview ] Service and Repair.
Perform the installation of the injectors in reverse order. When doing this note the following:
• Replace the O-rings on all injectors and lightly lubricate them with clean engine oil.
• Install the 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 the Engine Control Module (ECM) again. Refer to "Guided Functions".