Fuel Injectors, Checking

Fuel Injectors, Checking







Special tools and equipment
- VAG1526 A
- VAG1527 B
- VAG1594 A
- VAG1598/31

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; checking.

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 VAG1598/31 to wiring harness for engine control module; do not connect engine control module.







- 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.