Fuel Injectors, Checking
Fuel Injectors, Checking
Recommended special tools and equipment
- 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 Cylinder 1 Fuel Injector -N30- to Cylinder 4 Fuel Injector -N33-, Cylinder 5 Fuel Injector -N83-, Cylinder 6 Fuel Injector -N84- 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 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, checking.
- Ignition switched off.
Test sequence
- Pull connectors -1- off connection -2- of all fuel injectors.
Checking resistances of fuel injectors
- Test resistance of fuel injectors between terminals.
Specified value: 13.5 to 15.5 ohms
If specified value is not obtained:
- Replace malfunctioning fuel injector.
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.
- 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
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. connect test box for wiring test. Test Box, Connecting For Wiring Test
- Check wires between test box and 2-pin connector for open circuit according to wiring diagram.
Wire resistance: max. 1.5 ohms
Vehicles with engine code AHA
Vehicles with engine code ATQ
Continuation for all vehicles
- Also 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 1348/3A remote control with V.A.G 1348/3-2 adapter cable
- V.A.G 1602 tester for quantity of injected fuel
Without illustration:
- V.A.G 1594A connector test kit
Test requirement
- Fuel pressure must be OK, check. fuel pressure regulator and retaining pressure, checking. Testing and Inspection
WARNING: Fuel system is under pressure. Before opening system, place rags around the connection point. Then release pressure by carefully loosening connection.
Test sequence
- First, remove intake hose between Mass Air Flow (MAF) sensor and intake air scoop.
- Pull connectors -1- off connection -2- of all fuel injectors.
- Unscrew fuel rail from intake manifold (arrows).
- 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. connect test box for wiring test. Test Box, Connecting For Wiring Test
Checking for proper seal
- Switch ignition on.
Vehicles with engine code AHA
- Bridge sockets 1 + 4 of test box with the respective adapter cables.
Fuel Pump (FP) must run.
Vehicles with engine code ATQ
- Bridge sockets 62 + 65 of test box with the respective adapter cables.
Fuel Pump (FP) must run.
Continuation for all vehicles
- 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 malfunctioning fuel injector.
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.
- 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.
Vehicles with engine code AHA
- Bridge sockets 1 + 4 of test box with the respective adapter cables.
Fuel Pump (FP) must run.
Vehicles with engine code ATQ
- Bridge sockets 62 + 65 of test box with the respective adapter cables.
Fuel Pump (FP) must run.
Continuation for all vehicles
- Operate V.A.G 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: 90 to 125 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 malfunctioning 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 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.
- 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