Note: The following procedure applies only to models with the F8Q engine. On F9Q engines, the idle speed and deceleration speed are controlled by the electronic fuel injection module.
A conventional tachometer, which operates on the 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 this is usually not available to the motorist. If you cannot adjust the idle speed by ear or using the tachometer on the dashboard, you can use the following recommendations.
- a) Buy or borrow an appropriate tachometer.
- b) Entrust the work to a Renault service station or another specialist.
- c) Use the comparative method. The stroboscope is controlled by a gasoline engine running at the desired speed. If the stroboscope is aimed at a mark on the camshaft or fuel pump gear, the mark will appear stationary when the speed of both engines is the same (or multiples of an integer). The pulley will rotate at half crankshaft speed, but this will not affect the adjustment.
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 (refer to Section Removal, installation and adjusting the throttle cable).
Idle and Deceleration Speed Adjusting Screws - Lucas Pump
1 - Idle speed adjustment screw; 2 - Throttle lever; 3 - Deceleration speed adjustment screw; 4 - Fast idle lever; 5 - Fast idle cable tip
When the throttle lever touches the idle speed limiter, the engine idle speed should be as specified in Specifications value. If necessary, adjust them as follows.
Checking and adjusting idle speed
Lucas fuel pump
1. Loosen the lock nut on the idle speed adjustment screw. Turn the screw and tighten the lock nut (refer to the accompanying illustration).
2. Check the deceleration speed adjustment as described later in this Section.
3. Stop the engine and disconnect the tachometer.
Bosch fuel pump
1. Loosen the lock nut and turn the retard speed adjustment screw until it touches the throttle lever on the pump (refer to the accompanying illustration).
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2. Loosen the lock nut and turn the idle speed adjustment screw, then retighten the lock nut.
3. Check the 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
Lucas fuel pump
1. Insert a 4.0mm thick spacer or feeler gauge between the throttle lever on the pump and the retard speed adjustment screw (refer to the accompanying illustration).
2. Engine speed should increase to the values specified in Specifications deceleration revolutions.
3. If adjustment is necessary, loosen the lock nut and turn the retard speed adjustment screw. Finally, tighten the lock nut.
4. Remove the gasket or dipstick and let the engine idle.
5. Move the fast idle lever all the way to the flywheel and check that the engine speed increases to the specified Specifications fast idle speed. If necessary, loosen the lock nut and turn the fast idle adjusting screw, then retighten the lock nut.
6. Finally, disconnect the tachometer and turn off the engine.
7. After completing the adjustment, the deceleration damper should be adjusted as follows.
8. Loosen the two screws securing the shock absorber control arm to the throttle lever.
9. Insert a 1.0mm thick spacer or feeler gauge between the deceleration control lever and the end of the shock absorber, then slide the lever toward the limiter. 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 contacts the retard speed adjustment screw.
Bosch fuel pump
1. Loosen the lock nut and turn the retard speed adjustment screw until it touches the throttle lever on the pump (refer to the accompanying illustration).
2. Loosen the lock nut and turn the idle speed adjustment screw, then retighten the lock nut.
3. Check the deceleration speed as described later in this Section.
4. Turn off the engine and disconnect the tachometer.