2. Disconnect the wiring connectors (arrows) from the injectors (fig. 3.42 a).
3. Connect the VAG 1527 diode tester to the contacts of the first cylinder connector.
4. Try to start the engine with the starter. The tester light should blink.
5. Repeat the same testing procedure for injectors of cylinders 2-4. If the tester light does not flash on any of the cylinders, connect the tester to contact 1 and the "ground" of cylinder No.1 (fig. 3.42 b).
6. Try to start the engine with the starter. The tester light should light up.
7. If the tester lamp does not light, check the wires between the contacts of the two-pin wiring connector and the fuel pump relay for an open circuit. Wire resistance: max. 1.5 ohms.
8. If the tester light flashes on one or more cylinders, connect the VAG 1598/18 tester to the engine control unit wiring harness (fig. 3.34). Check the wires between the tester and the injector connectors for open circuit: cylinder 1 wiring connector - pin 2 + socket 7, cylinder 2 wiring connector - pin 2 + socket 6, cylinder 3 wiring connector - pin 2 + socket 28, cylinder 4 wiring connector - pin 2 + socket 4. Wire resistance: max. 1.5 ohms.
9. Additionally, check for short circuits between wires.
Specification resistance: ∞ Ohm.
10. Check the wires of contacts 1 of the injector wiring connectors for open circuit. Wire resistance: max. 1.5 Ohm. Additionally, check for short circuits between wires.
Specification resistance: ∞ Ohm.
Checking the injector resistance with a wire
11. Check the resistance between the injector contacts (fig. 3.42 in). Specification resistance: 14-17 Ohm.
12. Disconnect the three-pin wiring connector from the ignition coil.
13. Disconnect the four-pin wiring connector from the coolant temperature sensor 2 (fig. 3.42g).
14. Connect the VAG 1630 digital potentiometer using the auxiliary wires from the VAG 1594 to contacts 1 and 3 and set the resistance on the connected side to 15 kOhm.
15. Disconnect the wiring connector from the throttle body, oil pressure sensor and intake manifold pressure sensor, and disconnect the wiring harness from the intake pipe and thermostat housing.
16. Remove the high-pressure fuel line assembly with injectors from the intake manifold.
17. Position under the injector being tested and disconnect the wiring connectors from the injectors (fig. 3.42 d).
18. Try to start the engine with the starter. The injector should perform a pulsating injection of fuel.
19. Repeat the procedure for the remaining injectors. In this case, only the injector being tested should be connected.
20. Check the tightness of the injectors. The leakage should not exceed 2 drops per minute.
Caution: When installing the injectors, make sure that the sealing rings are not damaged.
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