Note. The following procedure only applies to models with the F8Q engine. On F9Q engines, idle speed and deceleration speed are controlled by the electronic injection module.
A conventional tachometer, which is pulsed by the ignition system, cannot be used on diesel engines. To do this, there is a diagnostic clutch to which Renault diagnostic equipment is connected, but it is usually not available to a car enthusiast. If you cannot adjust the idle speed by ear or by using the tachometer on the dashboard, the following recommendations can be used.
- a) Buy or borrow an appropriate tachometer.
- b) Entrust the work to a Renault workshop or another specialist.
- With) Use the comparative method. The stroboscope is driven by a gasoline engine running at the desired speed. If the strobe is pointed at the mark on the camshaft or fuel pump sprocket, the mark will appear stationary when both engines are running at the same speed (or multiples of an integer). The pulley will rotate at half the speed of the crankshaft, but this will not affect the adjustment.
Before starting the adjustment, warm up the engine to normal operating temperature (the cooling fan should turn on at least twice). Make sure the throttle cable is properly adjusted (refer to section Removal, installation and adjustment of the throttle cable).
Idle and Deceleration Speed Adjusting Screws - Lucas Pump
1 - Screw for adjusting idle speed; 2 - Gas lever; 3 - Screw for adjusting the speed of deceleration; 4 - Fast idle lever; 5 - Fast idle cable end
When the throttle lever touches the idle speed limiter, the engine idle speed must be as specified in Specifications value. If necessary, adjust them as follows.
Checking and adjusting idle speed
Fuel pump
1. Loosen the locknut on the idle speed screw. Turn the screw and tighten the locknut (refer to accompanying illustration).
2. Check deceleration speed adjustment as described later in this Section.
3. Stop the engine and disconnect the tachometer.
Bosch fuel pump
1. Loosen the locknut and back off the deceleration speed adjustment screw until it touches the throttle lever on the pump (refer to accompanying illustration).
2. Loosen the locknut and turn the idle speed adjustment screw, then re-tighten the locknut.
3. Check deceleration speed as described later in this Section.
4. Turn off the engine and disconnect the tachometer.
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.
Checking and adjusting the deceleration speed
Fuel pump
1. Insert a 4.0 mm thick shim or feeler gauge between the throttle lever on the pump and the deceleration speed adjustment screw (refer to accompanying illustration).
2. The engine speed should increase to the specified Specifications deceleration revs.
3. If adjustment is needed, loosen the locknut and turn the deceleration speed adjustment screw. Finally, tighten the locknut.
4. Remove the gasket or dipstick and let the engine idle.
5. Move the fast idle lever all the way to the flywheel and make sure that the engine speed has increased to the specified in Specifications fast idle speed. If necessary, loosen the locknut and turn the fast idle adjusting screw, then retighten the locknut.
6. Finally, disconnect the tachometer and turn off the engine.
7. After completing the adjustment, the deceleration damper must be adjusted as follows.
8. Loosen the two screws securing the shock control arm to the throttle control.
9. Insert a 1.0 mm thick shim or feeler gauge between the deceleration control arm and the end of the shock absorber, then slide the arm toward the stop. Make sure the throttle lever touches the deceleration speed adjustment screw, then tighten the two mounting screws.
10. Remove the gasket and make sure the throttle lever touches the deceleration speed adjustment screw.
Bosch fuel pump
1. Loosen the locknut and back off the deceleration speed adjustment screw until it touches the throttle lever on the pump (refer to accompanying illustration).
2. Loosen the locknut and turn the idle speed adjustment screw, then re-tighten the locknut.
3. Check deceleration speed as described later in this Section.
4. Turn off the engine and disconnect the tachometer.