Hyundai Elantra: Emission Control System > Exhaust Emission Control System > Description and 
Operation - Emission Control System - Hyundai Elantra MD 2010-2018 Service manualHyundai Elantra: Emission Control System > Exhaust Emission Control System > Description and Operation


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.
Open Loop air/fuel ratio is controlled by information pre-programmed into the ECM.
Closed Loop air/fuel ratio is constantly adjusted by the ECM based on information supplied by the oxygen sensor.

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