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 fuel injectors (N30 to N33) must be OK.
- Fuel Pump (FP) relay -J17- must be OK.
- 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 -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
- Ignition switched off.
Test sequence
Observe safety precautions.
Observe rules for cleanliness.
- Remove intake manifold upper section.
- Disconnect fuel injector connectors.
Resistance values of fuel injectors, checking
- Test resistance of fuel injectors between terminals.
Specified value: 14.0 to 20.0 Ohms
NOTE: Resistance value is valid at approx. 20°C. At higher temperatures, resistance value increases.
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 motor oil.
- Insert fuel injectors into fuel rail perpendicular and in the right position, and secure them with retaining clips.
- Position fuel distributor on lower section of intake manifold using secured fuel injectors 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.
- 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 Fuel Pump (FP) relay -J17- for open circuit according to wiring diagram.
Wire resistance: max. 1.5 Ohms
Checking activation
- Connect diode test lamp to 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.
Vehicles > 08.99
- 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
Vehicles 09.99 >
- 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
Continue for all vehicles
- 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
Not illustrated:
- V.A.G 1594A connector test kit
Test requirement
- Fuel pressure must be OK, check fuel pressure regulator and retaining pressure.
Test sequence
WARNING: Fuel system is under pressure. Before opening system, place rags around the connection point. Then release pressure by carefully loosening connection.
- Remove intake manifold upper section.
NOTE: Seal the intake channels in lower section of intake manifold using a clean rag.
- Disconnect fuel injector connectors.
- Remove fuel rail with fuel injectors and support
Checking Proper Seal
- Remove Fuel Pump (FP) Relay -J17- from relay carrier (relay position 12).
Note:
Remove battery Ground (GND) strap if tools are necessary for removing relays or control modules from the relay carrier.
Obtain radio code for radios with anti-theft coding before disconnecting battery.
Do not use metallic tools to pry off relays from relay carrier. The terminals could conduct electricity.
- Bridge terminals 4 + 6 on relay carrier using 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 valve.
- Disconnect connection between test box sockets.
- Insert Fuel Pump (FP) Relay -J17- into relay carrier.
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 distributor on lower section of intake manifold using secured fuel injectors 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.
- Generate readiness code.
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+.
- Remove Fuel Pump (FP) Relay -J17- from relay carrier (relay position 12)
Note:
Remove battery Ground (GND) strap if tools are necessary for removal of relays or control modules from the relay carrier.
Obtain radio code for radios with anti-theft coding before disconnecting battery.
Do not use metallic tools to pry off relays from relay carrier. The terminals could conduct electricity.
- Bridge terminals 4 + 6 on relay carrier using 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: 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: 85 to 105 ml per injector
- Disconnect connection between relay carrier terminals.
- Insert Fuel Pump (FP) Relay -J17- into relay carrier.
If measured value of one or more fuel injectors is below or above the indicated specified value:
- Replace malfunctioning fuel injector.
Note the following when installing the fuel injectors:
Insert fuel injectors into fuel rail perpendicular and in the right position, and secure them with retaining clips.
Position fuel distributor on lower section of intake manifold using secured fuel injectors 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.
- Generate readiness code.