With Generic Scan Tool
Fuel injectors, checking
Recommended special tools and equipment
- VAG 1526 multimeter or VAG 1715 multimeter
- VAG 1527 voltage test lamp
- VAG 1594 connector test kit
- Wiring diagram
Test requirements
- The respective fuses of fuel injectors (N30 to N33, N83, N84) must be OK.
- Fuel Pump (FP) Relay -J17- must be OK.
- Battery voltage must be at least 11.5 volts.
- All electrical consumers like, for example, lights and rear window heating must be switched off.
- Parking brake must be engaged or else daylight driving lights will be switched on.
- For vehicles with automatic transmission, selector lever must be in position -P- or -N-.
- If vehicle is equipped with an A/C system, it must be switched off.
- Ground (GND) connections between engine and chassis must be OK.
- Engine speed (RPM) sensor must be OK.
- Ignition switched off.
Test sequence
Resistance values of fuel injectors, checking
- Test resistance of fuel injectors between terminals.
Specified value: 12 to 17 Ohms
Note: Resistance value is valid at approx. 20 � C. At higher temperatures, resistance value increases.
If specified value is not obtained:
- Replace faulty fuel injector.
Note the following when installing the fuel injectors:
- Replace O-rings on all fuel injectors and wet them slightly with clean motor oil.
- Insert fuel injectors into fuel rail perpendicular and in the right position, and secure them with retaining clips.
- Position fuel distributor with secured fuel injectors on intake manifold and apply uniform pressure to press it in.
- Erase DTC memory of Engine Control Module (ECM).
- Generate readiness code.
Checking voltage supply
- Connect diode test lamp to connector of fuel injector to be tested terminal 1 and Ground (GND).
- Operate starter and test voltage supply for fuel injector.
LED must light up.
- Switch ignition off.
If LED does not light up:
- Check wire between 2-pin connector terminal 1 and the Fuel Pump (FP) Relay -J17- for open circuit according to wiring diagram.
Wire resistance: max: 1.5 Ohms
Activation and voltage supply, checking
- Connect diode test lamp to the connector terminals of the fuel injector to be checked.
- Operate starter and test activation of fuel injector.
LED should flicker.
- Switch ignition off.
If LED does not flicker:
- Connect test box to control module wiring harness.
- Check wires between test box and 2-pin connector for open circuit according to wiring diagram.
Wire resistance: max: 1.5 Ohms
- Also check wires for short circuit to B+ and Ground (GND).
Specified value: Infinity Ohms
If there is no malfunction in wire connection:
- Replace Motronic Engine Control Module (ECM) -J220-.
Fuel injectors, checking
Recommended special tools and equipment
- VAG 1348/3A remote control with VAG 1348/3-2 adapter cable
- V.A.G 1602 tester for quantity of injected fuel
Without illustration:
- VAG 1594A connector test kit
Test requirement
- Fuel pressure must be OK. Fuel pressure regulator and residual pressure.
Caution!: Fuel system is under pressure! Before opening system, place rags around the connection point. Then release pressure by carefully loosening connection.
Test sequence
- Disconnect fuel injector connectors.
- Remove mounting bolts from fuel distributor.
- Then remove the fuel distributor completely.
- Disconnect vacuum hose from fuel pressure regulator.
- Lift fuel rail with fuel injectors off intake manifold and support it.
- Connect test box to control module wiring harness.
Note: The only purpose of this step is to allow the Fuel Pump (FP) to run with the engine at standstill.
- Switch ignition on.
Injector leakage, checking
- Bridge sockets 1 & 4 of test box with the respective adapter cables. Fuel Pump (FP) must run.
- Check proper seal of fuel injectors (visual inspection). With Fuel Pump (FP) running, only 1 to 2 drops per minute should escape from each injector.
- Disconnect connection between test box sockets.
- Switch ignition off.
If fuel loss is greater:
- Replace faulty fuel injector.
Note the following when installing the fuel injectors:
- Replace O-rings on all fuel injectors and wet them slightly with clean motor oil.
- Insert fuel injectors into fuel rail perpendicular and in the right position, and secure them with retaining clips.
- Position fuel distributor with secured fuel injectors on intake manifold and apply uniform pressure to press it in.
- Erase DTC memory of Engine Control Module (ECM).
- Generate readiness code.
Injection quantity, checking
- Insert a fuel injector to be tested into a measuring tube of VAG 1602 tester for fuel injection quantity.
- Using respective adapter cables, connect one terminal of fuel injector to be checked to engine Ground (GND).
- Use adapter cable to connect second terminal of fuel injector to VAG 1348/3 remote control with VAG 1348/3-2 adapter cable.
- Connect alligator clip to B+.
- Switch ignition on.
- Bridge sockets 1 & 4 of test box with the respective adapter cables.
Fuel Pump (FP) must run.
- Operate VAG 1348/3 remote control for 30 seconds.
- Repeat test on other fuel injectors. Use new graduated measuring glasses for this.
Note: Also check spray pattern when checking injection quantity. Spray pattern must be the same for all injectors.
- After all fuel injectors have been activated, place graduated measuring glasses on a level surface and compare quantity of injected fuel.
Specified value: 133 to 157 ml. per per injector.
- Disconnect connection between test box sockets.
- Switch ignition off.
If the measured value of one or more fuel injectors is below or above the indicated specified value:
- Replace faulty fuel injector.
Installation of fuel injectors is the same in reverse order. Note the following:
- Replace O-rings on all fuel injectors and wet them slightly with clean motor oil.
- Insert fuel injectors into fuel rail perpendicular and in the right position, and secure them with retaining clips.
- Position fuel distributor with secured fuel injectors on intake manifold and apply uniform pressure to press it in.
- Erase DTC memory of Engine Control Module (ECM).
- Generate readiness code.