The electronic engine management system consists of a fuel tank, an electric fuel pump, a fuel filter, fuel feed and return hoses, a throttle body, a fuel rail, a fuel pressure regulator, four electronically controlled fuel injectors, and an electronic control unit (ECU) along with sensors, actuators and electrical wires.
The fuel tank on the Sedan and Coupe models is mounted vertically behind the rear seat backrest. On the Estate models, the fuel tank is mounted horizontally under the boot floor. The fuel level sensor is mounted on top of the fuel tank and can be replaced without removing the fuel tank.
An electric fuel pump with a circulation chamber is installed under the bottom at the rear of the vehicle. The fuel pump motor is constantly cooled by the fuel passing through it. The fuel pump has a one-way valve that, by shutting off the fuel system, maintains pressure in it even after the fuel pump is turned off. The valve also isolates the fuel tank from the rest of the fuel system. The pump also contains a pressure relief valve that limits the pressure in the fuel system.
The fuel pump delivers fuel through the fuel filter into the fuel line at a pressure higher than the fuel system pressure. The pressure regulator maintains the required pressure in the fuel system at a constant level and returns excess fuel to the fuel tank through the return fuel line. This constant circulation of fuel reduces the fuel temperature and prevents fuel evaporation.
Fuel injectors are electromagnetic valves that are opened and closed by an electronic control device (ECU), which determines the opening time and duration of fuel injection depending on the engine's crankshaft speed, throttle position, the amount of incoming air mass, the temperature of the air entering the engine, the temperature of the coolant and oxygen in the exhaust gases based on information received from sensors installed on and around the engine.
Air enters the engine through an air filter with a replaceable filter element. The temperature of the air entering the engine is regulated by a vacuum valve installed in the air filter. The vacuum valve mixes the cold air entering the engine with the air heated by the exhaust manifold. This valve, unlike the vane-type air flow meter, is sensitive to air density. This means that when the car is operated at high altitudes, the vacuum of the air is automatically taken into account without the need for a separate barometric air pressure measurement.
Idle speed is controlled by the idle speed control unit, which is mounted on the side of the throttle body, and the ignition system, which regulates idle speed by changing the ignition timing.
The oxygen content in the exhaust gases is constantly monitored by the ECU based on signals from the Lambda sensor, which is installed on the exhaust pipe. Based on the Lambda sensor information, the ECU determines the moment and duration of fuel injection in order to maintain the optimal ratio of the fuel mixture. There is also no need for manual adjustment of the CO content in the exhaust gases. In addition, to reduce emissions of harmful substances into the atmosphere, some models are equipped with a catalytic converter.
On some models, the ECU also controls the operation of the activated carbon filter.
Detecting faults in the electronic engine management system HFM is only possible using special diagnostic equipment.
Precautions
The fuel system is under constant pressure, even after the engine is turned off, so before carrying out any work on the fuel system, it is necessary to relieve the pressure.
To prevent the possibility of accidental short circuits in the electrical circuit and damage to the electronic components of the fuel injection system, always remove the ground cable from the battery.
Warning! Gasoline is extremely flammable and explosive, so care must be taken when working on any part of the fuel system.
Warning: The container that held the fuel contains fuel vapor and is potentially explosive.
Attention! Work on the fuel system must be carried out in a well-ventilated area, for which you can open all the windows and doors to create a draft.
Warning! When working on the fuel system, do not use open flames, electric welding or tools that may generate sparks. Make sure that a charged fire extinguisher is in the immediate vicinity of the work area.
Warning! Use goggles to protect your eyes from fuel getting into them. If fuel gets on your skin, rinse the area with plenty of water.
Caution! When working with the fuel system, keep it clean, as dirt that gets into the fuel system channels can block them, which will disrupt the normal operation of the engine.