Caution! The nominal idle speed is adjusted at the factory using the idle speed adjustment screw (SAS) and usually does not require additional adjustment during operation.
Attention! If the factory adjustment has been violated by mistake, a significant increase in the idle speed may occur, or its decrease may occur when an additional load on the engine is turned on (for example, an air conditioning compressor). If this happens, the adjustment is carried out as described below.
Caution! Before adjusting, make sure that the spark plugs, injectors, idle speed controller (ISC) are in good condition, and that the compression in the cylinders is in the range from the nominal to the maximum permissible value, and that the difference in compression between the cylinders does not exceed the maximum permissible value.
1. Prepare the vehicle for testing: warm up the engine to normal operating coolant temperature.
2. Connect the MUT-II tool to the 16-pin diagnostic connector.
Attention! When connecting the MUT-II device, the diagnostic output must be connected to ground.
3. Remove the waterproof plug from the base ignition timing adjustment connector.
4. Using a wire with an alligator clip, connect the terminal of the base ignition timing adjustment connector to ground.
5. Start the engine and let it idle.
6. Check the crankshaft speed in idle mode.
Nominal value:
- for engine 4G92 – (750±50) min⁻¹;
- for engine 4G93 – (800±50) min⁻¹.
Attention! On a new car (with a mileage of no more than 500 km), the idle speed may be 20–100 min⁻¹ less than the nominal. In this case, no adjustment is required.
If the engine stalls or the idle speed is too low on a car with a mileage of more than 500 km, then there is probably a deposit of foreign particles on the throttle valve, so it needs to be cleaned.
Fig. 7.7. Adjusting the base idle speed
7. If the idle speed differs from the nominal value, adjust it by turning the idle speed adjustment screw (SAS) (Fig. 7.7).
Caution: If the idle speed is higher than the nominal speed even with the idle speed adjustment screw (SAS) fully screwed in, check if the paint on the throttle lever stop screw is damaged (Fixed SAS), i.e. whether it has been adjusted before. If the paint is damaged, adjust the position of the throttle lever stop screw (Fixed SAS).
8. Turn the ignition key to the "OFF" position
9. Disconnect the wire with the alligator clip from the terminal of the base ignition timing adjuster and return the connector to its original position.
10. Start the engine and let it idle for 10 minutes. Make sure the engine idles normally.