Injection Quantity, Leakage and Spray Pattern of Injectors
Injection quantity, leakage and spray pattern of injectors, checking
Test conditions
- Fuel pressure OK
Removing fuel manifold tube
- Remove engine compartment cover.
- Remove connecting pipe between air cleaner housing and throttle valve body.
- Disconnect vacuum hose from fuel pressure regulator.
- Separate connectors for knock sensors and remove cable ties as necessary.
- Disconnect solenoid valve for secondary air injection from fuel manifold tube.
- Disconnect connectors from injectors and remove cable ties as necessary.
- Unbolt fuel manifold from variable intake manifold and pull it upward and off intake manifold together with injectors.
Checking injectors for leaks
- Place injector to be tested in a measuring glass from injection quantity tester VAG 1602.
- Connect test box VAG 1598/31 to wiring harness for engine control module; do not connect engine control module. Connecting VAG 1598/31 Test Box
- Bridge contacts 1 and 65 on test box using test leads from adapter set VAG 1594 A (this creates a Ground connection to one side of fuel pump relay coil).
- Switch ignition on.
NOTE: Once the ignition has been switched on, the fuel pump runs continuously even if the engine is not running. This is because with the ignition is switched on, the fuel pump relay receives its positive voltage supply via the engine electrics. The Ground voltage supply for the fuel pump relay comes via the cable bridge in the test box.
- Check injectors for leaks (visual check). When fuel pump is running, only 1 or 2 drops a minute should escape from each injector.
- If fuel loss is greater than this, switch off fuel pump (switch off ignition) and replace faulty injector.
Checking injection quantity
- Place injector which is to be tested into measuring glass of injection quantity tester VAG 1602.
- Connect one of injector contacts to engine Ground using a test cable and alligator clip from VAG 1594 A.
- Connect second contact of injector with remote control V.A.G 1348/3A, adapter lead VAG 1348/3-2 and auxiliary cable to positive.
- Switch ignition on.
- The fuel pump should run.
- Activate remote control VAG 1348/3A for 30 seconds.
- Perform measurements on all injectors.
- Once all four injectors have been actuated, place measuring glasses on a level surface.
Specification per injector:
A6 models S6 models
95 ... 115 ml 105 ... 125 ml
If the specified result is not attained for all injectors:
- Check fuel pressure. Fuel Pressure Regulator and Holding Pressure, Checking
If the specified results are not attained for one injector:
- Replace relevant 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 manifold 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 O-ring, make sure the plastic cap is not removed from the injector head. The O-ring must be pulled off over the plastic cap).
- Coat the O-rings with clean engine oil.
- Check to make sure that the retainer clamps are properly seated.