Fuel Injectors, Checking

Fuel Injectors, Checking







Special tools and equipment

- VAG 1526 A
- VAG 1527 B
- VAG 1594 A
- VAG 1598/31

Procedure

Cylinder bank 2 (left)







- Remove front engine cover (arrows).







- Disconnect connectors to Intake manifold change-over valve -N156- -1-.

Both cylinder banks, continued







- Disconnect all connectors for injectors of relevant cylinder bank, release connectors underneath for this purpose (arrow).

Checking internal resistance







- Connect multimeter to injector to measure resistance.
- Specified value: 11 to 13 Ohms (at room temperature).

- When the engine is at operating temperature the resistance is increased by approx. 4 to 6 Ohms.

If specified value is not obtained:

- Replace injector.

If specified value is obtained:

Checking power supply

Test requirements

- Fuse for injectors OK.
- Fuel pump relay OK. Testing and Inspection

NOTE: The injectors receive their power supply via the fuel pump relay.







- Connect voltage tester VAG1527 B as follows:

Connector Measure to
terminal
1 Engine ground

- Switch ignition on.
- LED should illuminate.

If the LED does not illuminate:

- Check wiring connection between terminal 1 and fuse for injector for open circuit.
- Repair open circuit, if necessary.

If the LED illuminates:

Checking actuation

Test requirements

- Internal resistance of the valve OK.







- Connect voltage tester VAG1527 B with measuring probes and plug-in adapters from VAG1594 A between terminal 2 (signal) and terminal 1 (positive); connector remains plugged in.
- Operate starter briefly (engine may start).
- LED should flash.

NOTE: Voltage testers with a low current draw continue to glow faintly between actuation from the engine control module (rather than extinguishing completely) and become slightly brighter when actuated.

If LED does not flash:

- Connect test box VAG 1598/31 to wiring harness for engine control module; do not connect engine control module. Wiring and Component Testing Using VAG1598/31 Test Box







- Check for open circuit and short to positive or Ground in following wiring connections:







- Repair any open/short circuit as necessary.

If no wiring malfunction is detected:

- Replace engine control module.