Measuring return rate of injectors with engine running — VW

🧭 Before you start

Fits: VW Touareg II (7P, 2010–2018)

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• Danger of functional impairment due to contamination/soilingObserve rules for cleanliness . — Connect auxiliary hose (1) to throttle (2) and hold in a measuring vessel.
• Clean and dry all return line connections (e.g. with standard commercially available cold cleaning solvent) before removing them.
• If one injector has a significantly higher return flow rate than the others, it must be renewed .

🔧 Engine codes this applies to

📋 Procedure

1. Pull off engine cover .
2. Clamp off fuel line behind throttle (1) with clamp up to 25 mm3094.
3. Detach fuel return line (arrow) behind throttle.
4. ⚠ Danger of functional impairment due to contamination/soilingObserve rules for cleanliness . — Connect auxiliary hose (1) to throttle (2) and hold in a measuring vessel.
5. Start engine and allow to idle for 2 minutes:

6. When the target value is reached, increase engine speed to 2,000 … 2,500 revs for around 2 minutes:
7. Clean and dry all return line connections (e.g. with standard commercially available cold cleaning solvent) before removing them.
8. At cylinder bank 1 (right), clamp off fuel line before throttle with clamp up to 25 mm3094(arrow B).
9. ⚠ Danger of functional impairment due to contamination/soilingObserve rules for cleanliness . — Pull return line connections off the injectors by pressing the two tabs downwards and simultaneously pulling the centre piece upwards in order to release them.
10. Fit hose lines onto return line connections of all 4 injectors.
11. Guide hose lines into measuring instrumentV.A.G 1348/2 B.
12. Start engine and allow to idle for several minutes:
13. ⚠ Danger of injectors being damaged due to increased engine speed.Do not accelerate the engine during the test. Engine must be idling all the time. — When the engine is warm and running at idling speed the return flow rates at each of the 4 return lines must not differ by more than a small amount.
14. At cylinder bank 2 (left ), clamp off fuel return line before throttle with clamp up to 25 mm3094(arrow A).
15. Repeat measurement of return rate at cylinder bank 2.
16. If one injector has a significantly higher return flow rate than the others, it must be renewed .
17. Installing fuel return lines
18. Bleed fuel system and check for leaks .

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