Idle speed and deceleration frequency — checking and adjustment (Renault Clio 1)

1. A conventional tachometer, which operates from ignition system pulses, cannot be used on diesel engines. For this purpose, there is a diagnostic coupling to which Renault diagnostic equipment is connected, but it is usually not available to the car owner. If you cannot adjust the idle speed by ear or using the tachometer on the dashboard, you can use the following recommendations.

• Buy or borrow an appropriate tachometer.
• Leave the work to a Renault dealer or other specialist.
• Use the comparative method. The strobe light is controlled by a gasoline engine running at the desired speed. If a stroboscope is aimed at a mark on the camshaft or fuel pump sprocket, the mark will appear stationary when the speed of both engines is the same (or a multiple of an integer). The pulley will rotate at half crankshaft speed, but this will not affect the adjustment.

2. Before starting adjustments, warm up the engine to normal operating temperature (the cooling fan should turn on at least twice). Make sure the accelerator pedal cable is adjusted correctly (see Chapter 5).

Checking and adjusting the idle speed

3. When the throttle lever touches the idle speed limiter, the engine idle speed should correspond to the value specified in the Specifications (see Specifications). If necessary, adjust it as follows. Lucas fuel pump

4. Loosen the lock nut on the idle speed adjustment screw. Turn the screw and tighten the lock nut (see illustration).





5. Check the deceleration frequency adjustment as described later in this Chapter.

6. Stop the engine and disconnect the tachometer.

Bosch fuel pump

7. Loosen the lock nut and back off the deceleration speed adjustment screw until it touches the throttle lever on the pump (see illustration).



8. Loosen the lock nut and turn the idle speed adjustment screw, then retighten the lock nut.

9. Check the deceleration frequency as described later in this Chapter.



10. Turn off the engine and disconnect the tachometer.

Checking and adjusting the deceleration frequency

11. Make sure the engine is warmed up to normal operating temperature (the fan should turn on at least twice), so that the idle speed corresponds to that specified in Specifications.

Lucas fuel pump

12. Insert a 4.0mm thick spacer or feeler gauge between the throttle lever on the pump and the adjustment screw.

13. The engine speed should increase to the deceleration frequency specified in the Specifications (see Specifications).

14. If adjustment is necessary, loosen the lock nut and turn the adjustment screw, then retighten the lock nut.

15. Remove the gasket or dipstick and check the idle speed as described above.

16. Move the throttle lever on the pump to increase the engine speed to 3000 rpm, then quickly release it. The deceleration time should be between 2.5-3.5 seconds, and the engine speed should drop to approximately 50 rpm below idle.

17. If the deceleration is too fast and the engine stalls, turn the deceleration adjustment screw 1/4 turn towards the throttle lever. If the deceleration is small, turn the screw 1/4 turn from the lever.

18. Retighten the lock nut, then check and adjust the idle speed as described above.

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19. Finally, disconnect the tachometer.

Bosch fuel pump

20. Insert a 4.0mm thick spacer or feeler gauge between the throttle lever on the pump and the deceleration speed adjustment screw (see illustration).





21. The engine speed should increase to the deceleration frequency specified in the Specifications (see Specifications).

22. If adjustment is necessary, loosen the lock nut and turn the deceleration frequency adjustment screw. Finally, tighten the lock nut.

23. Remove the gasket or dipstick and allow the engine to idle.

24. Move the fast idle lever all the way to the flywheel and check that the engine speed increases to the fast idle speed specified in the Specifications. If necessary, loosen the locknut and turn the fast idle adjusting screw, then retighten the locknut.

25. Finally, disconnect the tachometer and turn off the engine.

26. After completing the adjustment, the deceleration shock absorber must be adjusted as follows.

27. Loosen the two screws securing the shock absorber control arm to the throttle lever.

28. Insert a 1.0mm thick spacer or feeler gauge between the retarder control lever and the end of the shock absorber, then slide the lever toward the stopper. Make sure the throttle lever touches the deceleration speed adjustment screw, then tighten the two mounting screws.

29. Remove the gasket and make sure that the throttle lever contacts the deceleration speed adjustment screw.