The fuel pump provides a continuous supply of fuel through a cartridge-type filter into the fuel line under a slight overpressure. The fuel pressure regulator provides a constant pressure to the injection injectors. Excess fuel is returned to the fuel tank through the return line. This continuous supply system reduces the temperature of the fuel and prevents its evaporation.
Opening and closing of the injectors is carried out at the command of the electronic control unit (ECU), which calculates the moment and duration of injection based on the analysis of incoming information signals about engine speed, the position and speed of the throttle valve, the depth of vacuum in the intake piping, intake air temperature, coolant temperature, exhaust gas composition, etc.
The air sucked into the engine passes through the air cleaner, inside which a replaceable filter element made of thick paper is installed. The intake air temperature is controlled by a vacuum valve located in the air cleaner housing, which allows outside air to mix with the incoming air through the heater housing located above the exhaust manifold.
The temperature of the air entering the throttle body is measured by a sensor mounted on the intake manifold. In parallel, the sensor monitors the absolute pressure in the pipeline. All information enters the ECU and is used by it in determining the optimal air-fuel mixture in accordance with the current operating parameters of the engine.
The engine idle speed is controlled partly by the electronic throttle position module mounted on top of the throttle body, and partly by the ignition system, by changing the ignition timing settings. In view of the foregoing, the need for manual speed adjustments disappears and the possibility of its design of the system is not provided. Throttle position and speed information is supplied to the ECU by a special sensor, sometimes also referred to as a throttle potentiometer. The sensor is located on the left wall of the throttle body.
The oxygen content in the exhaust gases is continuously monitored by the ECU through a λ-probe installed in the front section of the exhaust system (ahead of the catalytic converter). Analyzing the incoming information, the ECU issues commands to adjust the ignition timing and injection duration, thereby forming the optimal composition of the air-fuel mixture. As a result, the need for manual adjustment of the CO content in the exhaust gases is also eliminated. All models covered in this manual come standard with a catalytic converter.
In addition to these functions, the ECU controls the operation of the evaporative emission control system.
It should be noted that the diagnostics of failures of all engine control systems is possible only with the help of a special electronic reader. In the event of any malfunction of the system, you should immediately contact the specialists of the Skoda branded service center, who will read and decrypt the codes recorded in the ECU memory unit, detected by the self-diagnosis system. The procedure for replacing failed system components is described in the following Sections of the Chapter.