Hyundai Elantra: 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.
Exhaust Emission Control System
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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). ...

Other information:

Hyundai Elantra AD (2016-2020) Service Manual: Input Speed Sensor Repair procedures
Inspection 1. Using the GDS, check the input/output speed sensor waveforms. A. Turn OFF the ignition switch. B. Connect the GDS to the Data Link Connector(DLC) on the lower crash pad. C. Ignition "ON" & Engine "ON". D. Check the input/output speed sensor waveforms at high spe ...

Hyundai Elantra AD (2016-2020) Service Manual: Seat Belt Pretensioner (BPT) Repair procedures
Removal 1. Disconnect the battery negative cable, and wait for at least three minutes before beginning work. 2. Separate the front seat belt (A) from the emergency fastening device. 3. Remove the door scuff trim. (Refer to Body - "Interior Trim") 4. Remove the center pillar trim. ...

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