Fuel Injector Volume, Leakage & Spray Pattern, Checking
Fuel Injector Volume, Fuel Injector Leakage and Spray Pattern of Injectors, Checking
Test conditions
- Fuel pressure OK Removing fuel rail
- Remove engine compartment cover and remove intake air duct between air cleaner housing and throttle housing.
- Detach vacuum hose from fuel pressure regulator.
- Disconnect connectors for knock sensors and remove cable ties where necessary.
- Detach solenoid valve for secondary air system from fuel rail.
- Disconnect connectors from injectors and remove cable ties where necessary.
- Unscrew fuel rail from intake manifold and lift fuel rail upward off intake manifold together with injectors.
WARNING!
Fire hazard! The fuel system is pressurized. Before loosening hose connections or opening the test connection (to measure fuel pressure), place a cloth around the connection. Then release pressure by carefully pulling off the hose or cap.
Checking fuel injectors for leaks
- Place fuel injector which is to be tested into a measuring glass from VAG1602 injection quantity tester.
- Connect VAG1598/31 test box to wiring harness for engine control module. Do not connect to the engine control module itself. Connecting VAG 1598/31 Test Box
- Bridge contacts 1 and 65 on test box using test leads from VAG1594A connector test kit. (This creates a Ground (GND) connection to one side of the 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 happens for the following reason, when the ignition is switched on the fuel pump relay receives a positive voltage supply via the central electrics. The Ground (GND) connection for the fuel pump relay is created via the jumper wire on the test box.
- Check fuel injectors for leaks (visual check). When fuel pump is running, only 1 or 2 drops should escape per minute from each injector.
- If fuel loss is greater, switch off fuel pump (turn off ignition) and replace faulty fuel injector.
Checking fuel injection volume
- Place fuel injector which is to be tested into a measuring glass from VAG1602 injection quantity tester.
- Connect one of fuel injector terminals to engine Ground (GND) using test lead and alligator clamp from VAG1594A connector test kit.
- Connect second fuel injector terminal to B+ using VAG1348/3A remote control, VAG134813-2 adapter cable and auxiliary cable.
- Switch ignition on.
- The fuel pump should run.
- Activate VAG1348/3A remote control for 30 seconds.
- Carry out measurement on all fuel injectors.
- When all fuel injectors have been actuated, place measuring glasses on level surface.
Specification: 95 to 115 ml at each fuel injector
If none of the fuel injectors delivers the specified quantity:
- Check fuel pressure. Testing and Inspection
If only one fuel injector fails to deliver the specified quantity:
- Replace malfunctioning fuel injector.
NOTE: When checking the fuel injection quantity, also check the spray pattern. The spray pattern should be the same for all the fuel 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 O-ring, 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 to make sure that the retainer clamps are properly seated.