Injection Quantity, Leakage and Spray Pattern of Fuel Injectors
Injection Rate, Leakage And Spray Pattern Of Injectors, Checking
Conditions
- Fuel pressure OK
Remove fuel rail
- Remove engine compartment cover.
- Remove connecting line between air cleaner housing and throttle housing.
- Disconnect vacuum hose from fuel pressure regulator.
- Disconnect connectors from injectors and remove cable ties where necessary.
- Unscrew fuel rail from intake manifold and pull fuel rail upward off manifold together with injectors.
Checking injectors for leaks
- Place injector which is to be tested into a measuring glass from injection quantity tester V.A.G 1602.
- Connect test box V.A.G 1598/31 to wiring harness for engine control module. Do not connect to engine control module itself. Scan Tool Testing
- Bridge contacts 1 and 65 on test box using test leads from adapter set V.A.G 1594 A. (This creates a Ground connection to one side of fuel pump relay coil.)
- Switch on ignition.
NOTE: Once the ignition has been switched on the fuel pump runs continuously, even if the engine is not running. This is because when the ignition is switched on the fuel pump relay receives a positive voltage supply via the central electrics. The Ground connection for the fuel pump relay is made via the cable bridge on the test box.
- Check injectors for leaks (visual check).
When fuel pump is running, only 1 or 2 drops should escape per minute from each injector.
If the fuel loss is greater:
- Switch off fuel pump (turn off ignition) and replace faulty injector.
Checking injection quantity
- Place injector which is to be tested into a measuring glass from injection quantity tester V.A.G 1602.
- Connect one injector contact to engine Ground using test lead and alligator clamp from V.A.G 1594 A.
- Connect second injector contact to positive using remote control V.A.G 1348/3 A, adapter cable V.A.G 1348/3-2 and auxiliary cable.
- Bridge contacts 1 and 65 on test box using test leads from adapter set V.A.G 1594 A.
- Switch on ignition.
Fuel pump should run.
- Activate remote control V.A.G 1348/3A for 30 seconds.
- Perform measurement on all injectors.
- Once all four injectors have been actuated, place measuring glasses on a level surface.
Specification at each injector: 95 ... 115 ml
If none of the injectors delivers the specified quantity:
- Check fuel pressure. Testing and Inspection
If only one injector fails to deliver the specified quantity:
- Replace affected injector.
NOTE: When checking the injection quantity, also check the spray pattern. The spray pattern should be the same for all the injectors.
Installation of the fuel rail together with injectors is performed in the reverse sequence. The following points should be noted when installing:
- Replace the O-rings at all opened connections. (When replacing the front Oring, make sure not to remove the plastic cap from the injector head. The O-ring must be pulled off over the plastic cap.)
- Moisten the O-rings with clean engine oil.
- Check that the retainer clamps are properly seated.
- Tighten fuel rail to intake manifold (10 Nm).