Scheme of the ignition timing control system
1 - ignition lock; 2 - engine speed sensor; 3 - coolant temperature sensor; 4 - solenoid valve for regulating the ignition timing; 5 - vacuum acceleration of the moment of ignition; 6 - main vacuum chamber; 7 - solenoid valve for regulating the ignition timing; 8 - subvacuum chamber; 9 - engine coolant temperature sensor.
Carburetor connection diagram
1 - suction valve; 2 - roller; 3 - bimetallic element; 4 - lever; 5 - suction interrupter; 6 - delay valve; 7 - fast idle cam; 8 - thrust lever; 9 - lever; 10 - suction opener; 11 - automatic suction relay; 12 - engine speed sensor; 13 - engine coolant temperature sensor; 14 - ignition switch; 15 - electric suction heater; 16 - thermostatic control valve; 17 - intake manifold hose.
The vacuum corrector of the distributor has a double-membrane design with vacuum and sub-vacuum chambers. In order to regulate the ignition timing, the ECU energizes the solenoid valves in the respective vacuum circuits of the main vacuum chamber and the sub-vacuum chamber.
Main vacuum chamber
When the engine speed is close to idle (1200 rpm or less), the ECU energizes the ignition timing control solenoid valve.
This leads to the connection of the carburetor intake pipe to the main vacuum chamber, which switches the ignition timing (the vacuum pressure in the tube is zero when the damper is in the idle position and increases with the opening angle.
When the engine speed increases to 1200 rpm, the ECU closes the ignition timing control solenoid valve. In this case, the intake manifold vacuum is directed towards the main vacuum chamber, increasing the ignition timing advance (coolant temperature below 80°C) the solenoid valves are energized, allowing the vacuum pressure from the intake manifold tube to reach the main vacuum chamber.
Ignition timing control using a sub-chamber
When the engine coolant temperature is not high (50°C or below), the ECU energizes the cold ignition timing control solenoid valve. As a result, the vacuum from the intake manifold is no longer directed to the atmosphere, but instead to the sub-vacuum chamber. As a result, the ignition advance by means of the main vacuum chamber is further increased by a constant angle (5°).
When the engine is warm or when the coolant temperature is high (above 50°C), the ECU reduces the excitation of the ignition timing control valve. As a result of vacuum from the intake manifold, it is connected to the atmosphere, which prevents the ignition timing from being advanced.
Throttle opening system
When the booster control vacuum switch is turned off by high pump pressure, the damper opening control solenoid valve is energized. As a result of this, the vacuum is directed from the intake manifold to the damper opener. The damper opens slightly to prevent the engine speed from dropping as a result of the load from the control system. If the engine speed drops below the set value (1200 rpm), ECU supports power transistor. When the electrical load switch is turned on when the headlights are turned on, the choke control solenoid valve is energized, directing intake manifold vacuum to the choke opener to deflect the choke slightly, preventing the engine speed from dropping due to electrical loading.
Air conditioning control system (for models with automatic transmission)
When the damper opening increases (at a coolant temperature of 74°C) during acceleration, the ECU turns off the air conditioner power relay for about 5 seconds. As a result, even when the air conditioner switch is turned on, the compressor is turned off, which reduces the load on the engine, improving acceleration efficiency.
Cold Mix Heater
This device is a thermistor heater with an additional coefficient of temperature resistance, installed between the carburetor and the intake manifold. If the coolant temperature is below 60°C, the ECU energizes the cold mixture relay. The cold air/fuel mixture is heated before entering the combustion chamber to improve the combustion process.
Electrical automatic suction system
This system in the carburetor provides heating of the bimetallic suction spring with an electric heater. After starting the engine, the spring heats up, as a result, the bimetal element gradually opens the suction valve by means of a thermal expander and pushes down the stop lever. The lower the temperature during engine start, the tighter the suction valve closes, making it easier to start the engine.