Checking return flow rate of injectors at starter cranking speed — AUDI

🧭 Before you start

Fits: Audi A6/A7 C7 (4G, 2011–2018)

• Special tools named: 3094, VAS 6684/1
• Renewed: o-ring

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• Risk of malfunctions caused by dirt.Observe rules for cleanliness . — Remove engine cover panel .
• If fuel comes out of one injector, that injector must be renewed .
• Renew O-ring if it is damaged or deformed.Lubricate all O-rings with engine oil or assembly oil before installing.
• If there is any air left in the fuel system, the engine may switch to the backup mode ('emergency running' mode) during the road test. Switch off the engine and erase the event memory. Then continue the road test.

🔧 Engine codes this applies to

📐 20 workshop diagrams for ASB

Real factory drawings for this job — timing marks, bolt locations and routing. Locked in the free view.

📋 Procedure

1. ⚠ Risk of malfunctions caused by dirt.Observe rules for cleanliness . — Remove engine cover panel .
2. Clean all return line connections with engine cleaner or brake cleaner and dry.
3. Clamp off fuel return line downstream of restrictor using a hose clamp, up to 25 mm 3094.
4. Remove air cleaner housing .
5. Detach bracket (1) with wiring harness from high-pressure lines towards front and push upwards slightly.

6. Disconnect fuel return hoses from injectors; to do so, press down both tabs and at the same time pull centre piece up to release connection (arrow).
7. Unscrew bolt (1) and detach coolant expansion tank.
8. Unplug electrical connector (2) and move coolant expansion tank to one side with coolant hoses attached.
9. Move clear electrical wiring harness at bracket (1).
10. Remove bolts (arrows) and detach bracket.
11. Disconnect fuel return hoses from injectors; to do so, press down both tabs and at the same time pull centre piece up to release connection (arrow).
12. Connect hoses of return flow meter VAS 6684/1 to return line connections of all six injectors.
13. Install air cleaner housing .
14. Operate starter three times (wait approx. 20 seconds each time after operating starter to prevent it from overheating).
15. If fuel comes out of one injector, that injector must be renewed .
16. Remove hose clamp 3094 from fuel return line.
17. Remove air cleaner housing again .
18. Check O-ring for fuel return line connection for damage and deformation. [Note: Renew O-ring if it is damaged or deformed.Lubricate all O-rings with engine oil or assembly oil before installing.]
19. Push the return line connections carefully over the new seals and onto the injectors.
20. Then press down release pin carefully.
21. Install air cleaner housing .
22. Install engine cover panel .
23. Erase any entries in event memory resulting from this procedure , Vehicle self-diagnosis, then Interrogate event memory. [Note: If there is any air left in the fuel system, the engine may switch to the backup mode ('emergency running' mode) during the road test. Switch off the engine and erase the event memory. Then continue the road test.]

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