Hyundai Sonata: Description and Operation - Exhaust Emission Control System - Emission Control SystemHyundai Sonata: Description and Operation

Description
Exhaust emissions (CO, HC, NOx) are controlled by a combination of engine modifications and the addition of special control components.
Modifications to the combustion chamber, intake manifold, camshaft and ignition system form the basic control system.
These items have been integrated into a highly effective system which controls exhaust emissions while maintaining good drivability and fuel economy.
Air/Fuel Mixture Control System [Multiport Fuel Injection (MFI) System]
The MFI system uses signals from the heated oxygen sensor to activate and control the injector installed in the manifold for each cylinder, thus precisely regulating the air/fuel mixture ratio and reducing emissions.
This in turn allows the engine to produce exhaust gas of the proper composition to permit the use of a three way catalyst. The three way catalyst is designed to convert the three pollutants [hydrocarbons (HC), carbon monoxide (CO), and oxides of nitrogen (NOx)] into harmless substances. There are two operating modes in the MFI system.
1.
Open Loop air/fuel ratio is controlled by information programmed into the ECM.
2.
Closed Loop air/fuel ratio is adjusted by the ECM based on information supplied by the oxygen sensor.
    Catalytic Converter Description and Operation
    Description The catalytic converter of the gasoline engine is a three way catalyst. It oxidizes carbon monoxide and hydrocarbons (HC), and separates oxygen from the oxides of nitrogen (NOx). [ ...

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