Fuel Injector: Testing and Inspection
DIGIFANT IIFuel Injectors - Electrical Checks Voltage Supply
Requirements
- Hall sender OK (ignition coil produces spark while cranking starter).
- Voltage supply from terminal 87 of fuel pump relay is OK. (Golf)
- Voltage supply from terminal 87 of power supply relay is OK. (Jetta)
- Disconnect harness connector (1) from injector wiring harness (2).
- Bridge terminals of harness connector (1) with LED Tester US 1115.
- Crank starter.
- LED Tester must flicker.
If LED Tester does not flicker,
- Connect multi meter US 1119 to terminal 2 of the injection harness connector (1) and to ground.
- Switch the ignition ON.
- Specification: Battery voltage.
If the voltage is not OK,
- Repair wiring to terminal 87 of the fuel pump relay (Golf) or power supply relay (Jetta) using the appropriate wiring diagram.
If the voltage was OK,
- Disconnect the multi-pin connector from the Digifant E.C.U.
- Check continuity of the wire from terminal 1 of the fuel injection wiring harness connector (1) to terminal 12 of the Digifant E.C.U. connector.
If the continuity was OK,
- Replace the Digifant E.C.U.
Injector Resistance
- Disconnect harness connector (1) from fuel injection wiring (2).
- Set US 1119 to 200 ohm scale and measure resistance across connector terminals (2). 3.7 to 5.0 ohms
It total resistance is not within specifications, the following readings indicate one or more injectors are not functioning properly:
5.0 to 6.7 ohms - 3 injectors OK
7.5 to 10.0 ohms - 2 injectors OK
14.0 to 18.0 ohms - 1 injector OK
Note: Individual injectors can only be checked when the fuel rail is removed.
To check individual injectors:
- Remove fuel rail.
- Measure resistance across terminals of each injector. 14.0 to 18.0 ohms
If resistance is not within specification,
- Replace injector(s) and re-check total resistance.
If all injectors check OK, but total resistance is high,
- Replace fuel injector wiring harness (2).
Leak Testing, Delivery Quantity, and Spray Pattern
Requirements
- Resistance values of fuel injectors are within specifications.
- Remove crankcase ventilation valve with hose to the throttle body.
- Remove the intake air boot with the air supply hose to the idle stabilizer.
- Remove the idle stabilizer with the hose to the intake manifold and the stabilizer mounting bracket.
- Disconnect the vacuum hoses from the front of the throttle body.
- Separate the throttle body from the intake manifold and swing aside.
- Use new gasket when re-installing
- Torque bolts to 20 Nm (15 ft-lbs.)
- Disconnect harness plug from the fuel injector wiring harness (1).
- Remove the two 5 mm Allen head bolts mounting the fuel rail assembly to the wiring harness (2).
- Remove the 6 mm Allen head bolt from the fuel pressure regulator bracket (3).
- Pop all four fuel injectors out of the cylinder head simultaneously.
- Use new 0-rings lubricated with engine oil when re-assembling.
- Do not use silicone lubricant on fuel injection hoses or components.
- Disconnect the wiring harness plugs from the fuel injectors.
Leak Testing
- Remove the air cleaner assembly.
- Place VW 1348/2B measuring beakers onto the air filter mounting flange.
- Swing fuel injector assembly around and place on VW 1348/2B so that each injector sits in a measuring beaker.
- Remove the fuel pump relay and Install remote control switch US 4480/3 In its place.
- Switch remote control US 4480/3 ON.
- Fuel pumps run.
- Fuel system is pressurized.
- Observe injector tips for 1 minute.
- No more than 2 drops may leak from each injector in one minute.
Checking Delivery Quantity/Spray Pattern
WARNING: Fire hazard. Do not smoke or have anything in the area that can ignite fuel when working on the fuel system.
- US 4480/3 connected.
- Connect a spare injector wiring harness (P/N 037 133 339) to the fuel injectors and connect your self-made jumper harness (see Special Tools list).
Note: If a spare wiring loom is not available,
- Connect your self-made jumper harness to one injector at a time and test each Injector individually.
- Connect one lead of the jumper harness to the positive battery post.
- Switch US 4480/3 remote control switch ON.
- Connect remaining lead of jumper harness to negative battery post for exactly 15 seconds while observing injector spray pattern.
- Spray pattern must be even and cone-shaped.
- Delivery quantity for each injector must be a minimum of 50 cc after 15 seconds.
- Difference between high and low delivery quantities must not exceed 5 cc.
If any of the specifications are not met,
- Check the fuel pump pressure and delivery rate if the delivery quantity is low for all injectors.
- Clean fuel injection system using Volkswagen solvent C 001 600.00 with adapter kit USC16.