Hyundai Elantra MD/UD: Emission Control System > Exhaust Emission Control System > 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 pre-programmed
into the ECM.
|
| 2. |
Closed Loop air/fuel ratio is constantly adjusted by the ECM based
on information supplied by the oxygen sensor.
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