Emission control system
All models with petrol engines can use unleaded petrol. Engine management systems select the optimum mode for a combination of vehicle dynamics, minimal fuel consumption and reduction of harmful substances in exhaust gases.
In order to reduce atmospheric pollution from incompletely burned hydrocarbons and evaporating gases and create optimal conditions for engine operation, the following exhaust gas toxicity reduction systems are used:
- crankcase ventilation system that reduces the emission of contaminants from the engine lubrication system (installed on all models);
- catalyst that neutralizes harmful substances in exhaust gases (installed on most models);
- a fuel vapor recovery system that reduces the output of gaseous hydrocarbons and the fuel tank (installed on all models).
In addition, on some models, an exhaust gas re-burning system is installed (EGR) and a forced air injection system that reduces the amount of unburned fuel in the exhaust.
All diesel engines are also equipped with a crankcase ventilation system. Also, on some models, a catalyst and an exhaust gas re-burning system are installed (EGR).
Crankcase ventilation system
To reduce the emission of unburned hydrocarbons from the crankcase to the atmosphere, with a sealed engine, crankcase gases and oil vapor are drawn from the crankcase into the air supply path to the engine and are afterburned by the engine.
Catalytic converter on models with petrol engines
To reduce emissions of harmful substances with exhaust gases, a catalytic converter is installed on most models. On all models with a catalytic converter, the fuel supply system is closed-type, i.e., based on the signal from the Lambda sensor installed in the front exhaust pipe, the ECU constantly optimizes the composition of the fuel-air mixture.
For normal operation of the Lambda sensor, it has a heater, which is controlled by the ECU and maintains a constant temperature of the Lambda sensor through the Lambda sensor relay. Depending on the oxygen content in the exhaust gases, the lambda sensor induces a voltage of 0.1 V (high oxygen, lean mixture) up to 0.9 V (low oxygen, rich mixture). Based on this data, the engine control unit changes the opening time of the fuel injectors and changes the fuel ratio in the fuel mixture. The stoichiometric ratio of the fuel mixture, at which its complete combustion occurs and there are no harmful substances in the exhaust, is 14.7 weight parts of air per 1 part of fuel.
Additional air supply to the exhaust system reduces the emission of harmful substances and CO. The air pump, driven by the auxiliary drive belt, pumps pressurized air into the exhaust manifold, where fresh air mixes with incompletely burned fuel particles. Fresh air produces the final oxidation of unburned substances, turning them into carbon dioxide and water vapor.
To reduce the emission of nitrogen oxide into the atmosphere, along with the exhaust gases, part of the exhaust gases through the EGR valve enters the intake manifold and is re-burned.
Exhaust Catalytic Converter on Diesel Models
On models with diesel engines, an oxidizing catalyst is installed in the exhaust system, which neutralizes gaseous hydrocarbons and CO in the exhaust gases. On some models, a special filter is installed in the exhaust system that traps particulate hydrocarbons.
On some models, an exhaust gas re-burning system is installed. When this system works to reduce the emission of nitrogen oxide into the atmosphere along with the exhaust gases, part of the exhaust gases through the valve of the exhaust gas re-burning system enters the intake manifold and is re-burned. The electro-pneumatic exhaust gas re-burning system is controlled by the ECU.
Evaporative emission system on models with petrol engines
To prevent fuel vapors from entering the atmosphere, a fuel vapor recovery system with a canister filled with charcoal is used. Fuel vapors from the fuel tank and carburetor float chamber are collected in a charcoal canister located under the left fender. Fuel vapors from the charcoal canister are drawn into the throttle body due to the pressure difference and burned in the engine cylinders. The process of pulling fuel vapors from the charcoal canister through the cleaning valve is controlled by a thermal valve, which opens the cleaning valve only after the engine has warmed up to a certain temperature. This is necessary in order to prevent over-enrichment of the mixture when the engine is running cold.
Exhaust system
The exhaust system consists of an exhaust manifold, an exhaust pipe, mufflers and connecting pipes, a catalytic converter and brackets and rubber suspensions.
The turbocharger fitted to diesel models is oil-cooled and has a pressure control valve. If the control valve fails, the engine overload protection valve is activated and, through the actuator, reduces the fuel supply by the high pressure fuel pump to the level of a diesel engine without turbocharging.