Fuel Injectors, Checking
Fuel injectors, checking
Recommended special tools and equipment
- VAG1526 multimeter or VAG1715 multimeter
- VAG1527 voltage test lamp
- VAG1594 connector test kit
- Wiring diagram
Test requirements
The respective fuses of Motronic Engine Control Module (ECM) -J220- must be OK.
- Fuses -1, 2, 3, 4 and 7- in protective housing (plenum chamber, left) 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, for example, 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.
Engine Speed (RPM) Sensor, Checking
- Ignition switched off.
Test sequence
- Remove intake air hose between Mass Air Flow (MAF) sensor and throttle valve control module, item 1 .
- Remove upper part of intake manifold (with both intake manifold side parts), item 8 .
NOTE: When removing the upper part of the intake manifold, ensure that the alignment pins are positioned in lower part of the intake manifold and do not fall into the intake channels!
- Disconnect harness connector of fuel injectors (Cylinder 1 Fuel Injector -N30- to Cylinder 4 Fuel Injector -N33-, Cylinder 5 Fuel Injector -N83-to Cylinder 8 Fuel Injector -N86-), cylinder bank 1 and 2.
NOTE:
- Bank 1 = Cylinder bank 1, in direction of travel, right
- Bank 2 = Cylinder bank 2, in direction of travel, left
Checking resistance values of fuel injectors
- Test resistance of fuel injectors between terminals.
Specified value: 14.0...20.0 Ohms
If specified value is not obtained:
- Replace faulty fuel injector (Cylinder 1 Fuel Injector -N30- to Cylinder 4 Fuel Injector -N33-, Cylinder 5 Fuel Injector -N83- to Cylinder 8 Fuel Injector -N86-), item 9 .
Installation of fuel injectors is the same in reverse order. Note the following:
- O-rings on all fuel injectors must be replaced and coated lightly with clean motor oil.
- Insert fuel injectors into fuel distributor 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.
- The connectors must audibly engage on valves when attached.
- Erase DTC memory of Engine Control Module (ECM), 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:
Checking wiring
- 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
- 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-.