Fuel Injectors, Checking For Leaks, Injection Quantity and Spray Pattern
Fuel Injectors, Checking for Leaks, Injection Quantity and Spray Pattern
Special tools, testers and auxiliary items required
• Fuel injection quantity tester (V.A.G 1602)
Conditions
• Fuel pressure OK.
- Remove intake manifold.=> [ Intake Manifold Assembly Overview ] Intake Manifold Assembly Overview
- Separate electrical connections at fuel injectors by pressing release tabs down and then inward - arrow -.
• When the connection is released, the release tab remains in the lower position. When reconnecting the connector, the release tab engages upward again.
- Disconnect fuel supply line - 1 - and fuel return line - 2 - from fuel rail. Use a clean rag to catch exiting fuel.
• Vehicles with engine code BSB are without the fuel return line - 2 - in the illustration.
- Disconnect vacuum hose from fuel pressure regulator.
- Remove bolts from fuel rail - arrows - (: 10 Nm).
- Pull fuel rail (on transmission side) with injectors upward uniformly from intake manifold and set aside in engine compartment on a clean cloth.
- Reconnect fuel supply line - 1 - and fuel return line - 2 - to fuel rail.
• Vehicles with engine code BSB are without the fuel return line - 2 - in the illustration.
Injectors, checking for leaks
- Insert fuel injector to be tested into measuring container of fuel injection quantity tester (V.A.G 1602).
- Connect test box (V.A.G 1598/31) at wiring harness to Engine Control Module (ECM) (-J623-). Do not connect ECM => [ Wiring and Components, Checking with Test Box VAG 1598/31 ] Wiring and Components, Checking with Test Box VAG 1598/31.
- Bridge terminals 1 and 65 at test box using adapter cables from connector test kit (V.A.G 1594 A) (this step supplies Ground to one side of relay coil of Fuel Pump relay).
- Switch ignition on.
• After switching the ignition on, the Fuel Pump (FP) will run continuously, even with the engine not running, for the following reason: After switching the ignition on, the Fuel Pump (FP) relay supplies continuous B+ via central electronics. Ground is supplied to the FP relay via the bridge in the test box.
- Check injectors for leaks (visual inspection). Only 1 to 2 drops per minute may emit from each valve when Fuel Pump (FP) is running.
- If fuel loss is greater, stop Fuel Pump (FP) from running (switch off ignition) and replace faulty fuel injector.
Injection quantity, checking
- Insert fuel injector to be tested into measuring container of fuel injection quantity tester (V.A.G 1602).
- Connect one terminal of fuel injector to engine Ground (GND) using an adapter cable and an alligator clip from connector test kit (V.A.G 1594 A).
- Connect second contact of fuel injector with remote control (V.A.G 1348/3A), adapter cable (V.A.G 1348/3-2) and assisting cable to Positive (B+).
- Switch ignition on.
• Fuel Pump (FP) must run.
- Operate remote remote control (V.A.G 1348/3A) for 30 seconds.
- Perform measurement with all fuel injectors.
- After all 4 fuel injectors have been activated, place measuring containers on a level surface.
Specified value per fuel injector:
• 121 to 131 ml
If specified value is not obtained for all fuel injectors:
- Check fuel pressure => [ Fuel Pressure Regulator and Residual Pressure, Checking ] Testing and Inspection
If specified value is not obtained for a fuel injector:
- Replace appropriate fuel injector.
• While checking the injection quantity, the spray pattern should also be checked. The spray pattern must be the same for all fuel injectors.
Installation of fuel rail with fuel injectors is the same in reverse order. Observe the following points when installing:
• Replace O-rings at all opened connection points. (To replace the front O-rings, push the O-rings over the plastic cap at the head of the injector - under no circumstances may the plastic cap be removed).
• Lubricate O-rings with clean engine oil.
• Check clips for proper seating.
• Check that fuel injectors are installed in correct position.