Fuel Injectors, Checking
Fuel Injectors, Checking
Recommended special tools and equipment
- V.A.G 1331 torque wrench (5 to 50 Nm)
- V.A.G 1526 multimeter or V.A.G 1715 multimeter
- V.A.G 1527 voltage test lamp
- V.A.G 1594 connector test kit
- Wiring diagram
Test requirements
- The respective fuses of fuel injectors (-N30- to -N33-) must be OK.
- Fuel Pump (FP) Relay -J17- must be OK, check.
- Battery voltage must be at least 11.5 volts.
- All electrical consumers such as: lights and rear window defroster must be switched off.
- Parking brake must be engaged or else day time driving lights will be switched on.
- For vehicles with automatic transmission, selector lever must be in -P-.
- 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, checking. Testing and Inspection
- Ignition switched off.
Test sequence
- Observe safety precautions.
- Observe rules for cleanliness.
- Disconnect harness connectors for Cylinder 1 Fuel Injector -N30- through Cylinder 4 Fuel Injector -N33-.
Resistance values of fuel injectors, checking
- Test resistance of fuel injectors between terminals.
Specified value: 12.0 to 17.0 Ohms
NOTE: Resistance value is valid at approx. 20 degrees C. At higher temperatures, resistance value increases.
If specified value is not obtained:
- Replace faulty fuel injector (Cylinder 1 Fuel Injector -N30- through Cylinder 4 Fuel Injector -N33-).
Note the following when installing the fuel injectors:
- Replace O-rings on all fuel injectors and wet them slightly with clean engine oil.
- Insert fuel injectors into fuel rail perpendicular and in the right position, and secure them with retaining clips.
- Position fuel rail with secured fuel injectors on intake manifold and apply uniform pressure to press it in.
- The connectors must audibly engage on injectors when attached.
- Erase DTC memory of Engine Control Module (ECM). Diagnostic mode 4: Reset/erase diagnostic data. Diagnostic Mode 4: Reset/Erase Diagnostic Data
- Generate readiness code. Monitors, Trips, Drive Cycles and Readiness Codes
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
- Erase DTC memory of Engine Control Module (ECM). Diagnostic mode 4: Reset/erase diagnostic data. Diagnostic Mode 4: Reset/Erase Diagnostic Data
- Generate readiness code. Monitors, Trips, Drive Cycles and Readiness Codes
Checking activation
- 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:
- Check wires to control module according to wiring diagram.
Check wires to control module
- Connect test box to control module wiring harness. connect test box for wiring test. Test Box, Connecting For Wiring Test
- Check wires between test box and 2-pin connector to Engine Control Module (ECM) for open circuit according to wiring diagram.
Wire resistance: max. 1.5 Ohms
- Check wires for short circuit to B+ and to Ground (GND).
Specified value: Infinite Ohms
If there is no malfunction in wire connection:
- Replace Motronic Engine Control Module (ECM) -J220-.
Injection quantity and proper seal of fuel injectors, checking
Recommended special tools and equipment
- V.A.G 1331 torque wrench (5 to 50 Nm)
- V.A.G 1348/3A remote control with V.A.G 1348/3-2 adapter cable
- V.A.G 1594A connector test kit
- V.A.G 1602 tester for quantity of injected fuel
Without illustration:
- V.A.G1598/31 test box
Test requirements
- Fuel pressure must be OK, check. fuel pressure regulator and retaining pressure, checking. Fuel Pressure Regulator and Residual Pressure, Checking
- Ground (GND) connections between engine and chassis must be OK.
- Ignition switched off.
Test sequence
Observe safety precautions.
Observe rules for cleanliness.
- Disconnect harness connectors for Cylinder 1 Fuel Injector -N30- through Cylinder 4 Fuel Injector -N33-.
- Disconnect vacuum hose -1- from fuel pressure regulator -2-
- Remove mounting bolts from fuel distributor.
- Lift fuel rail with fuel injectors off intake manifold and support it (fuel lines remain connected).
- Connect test box to control module wiring harness. connect test box for wiring test. Test Box, Connecting For Wiring Test
NOTE: The only purpose of this step is to allow the Fuel Pump (FP) to run with the engine at standstill.
- Switch ignition on.
Checking Proper Seal
- Bridge sockets 2 + 65 of test box with the respective adapter cables. Fuel Pump (FP) must run.
- Check fuel injectors for proper seal (visual inspection). With Fuel Pump (FP) running, only 1 to 2 drops per minute should escape from each valve.
- Disconnect connection between test box sockets.
- Switch ignition off.
If fuel loss is greater:
- Replace faulty fuel injector (Cylinder 1 Fuel Injector -N30- through Cylinder 4 Fuel Injector -N33-).
Note the following when installing the fuel injectors:
- Replace O-rings on all fuel injectors and wet them slightly with clean engine oil.
- Insert fuel injectors into fuel rail perpendicular and in the right position, and secure them with retaining clips.
- Position fuel rail with secured fuel injectors on intake manifold and apply uniform pressure to press it in.
- The connectors must audibly engage on injectors when attached.
- Erase DTC memory of Engine Control Module (ECM). Diagnostic mode 4: Reset/erase diagnostic data. Diagnostic Mode 4: Reset/Erase Diagnostic Data
- Generate readiness code. Monitors, Trips, Drive Cycles and Readiness Codes
Checking injection quantity
- Insert a fuel injector to be tested into a measuring tube of V.A.G 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 V.A.G 1348/3 remote control with V.A.G 1348/3-2 adapter cable.
- Connect alligator clip to B+.
- Switch ignition on.
- Bridge sockets 2 + 65 of test box with the respective adapter cables. Fuel Pump (FP) must run.
- Operate remote control for 30 seconds.
- Repeat test on other fuel injectors. Use new graduated measuring glasses for this.
NOTE: 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 165 ml 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 (Cylinder 1 Fuel Injector -N30- through Cylinder 4 Fuel Injector -N33-).
Note the following when installing the fuel injectors:
- Replace O-rings on all fuel injectors and wet them slightly with clean engine oil.
- Insert fuel injectors into fuel rail perpendicular and in the right position, and secure them with retaining clips.
- Position fuel rail with secured fuel injectors on intake manifold and apply uniform pressure to press it in.
- The connectors must audibly engage on injectors when attached.
- Erase DTC memory of Engine Control Module (ECM). Diagnostic mode 4: Reset/erase diagnostic data. Diagnostic Mode 4: Reset/Erase Diagnostic Data
- Generate readiness code. Monitors, Trips, Drive Cycles and Readiness Codes