Hyundai Accent (HC): Emission Control System / Exhaust Emission Control System

Hyundai Accent (HC) (2017 - 2022) Service Manual / Emission Control System / Exhaust Emission Control System

Contents:

Catalytic Converter
CVVT (Continuously Variable Valve Timing) System

Catalytic Converter

- 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).

- Removal and Installation [WCC]

1.Remove the exhaust manifold.(Refer to Engine Mechanical System - "Exhaust Manifold")

[UCC]

1.Remove the catalytic converter & center muffler.(Refer to Engine Mechanical System - "Muffler")

CVVT (Continuously Variable Valve Timing) System

- Description Continuous Variable Valve Timing (CVVT) system advances or retards the valve timing of the intake and exhaust valve in accordance with the ECM control signal which is calculated by the engine speed and load.By controlling CVVT, the valve over-lap or under-lap occurs, which makes better fuel economy and reduces exhaust gases (NOx, HC) and improves engine performance through reduction of pumping loss, internal EGR effect, improvement of combustion stability, improvement of volumetric efficiency, and increase of expansion work.This system consists of

– the CVVT Oil Control Valve (OCV) which supplies the engine oil to the cam phaser or takes out the engine oil from the cam phaser in accordance with the ECM PWM (Pulse With Modulation) control signal,

– the CVVT Oil Temperature Sensor (OTS) which measures the engine oil temperature,

– and the Cam Phaser which changes the cam phase by using the hydraulic force of the engine oil.

The engine oil which is supplied from the CVVT oil control valve changes the cam phase in the direction (Intake Advance/Exhaust Retard) or opposite direction (Intake Retard/Exhaust Advance) of the engine rotation by rotating the rotor connected with the camshaft inside the cam phaser.

[Intermediate Lock CVVT] It increases the retarded amount compared to the default state to expand the operating range of the variable valve timing system.The cam phase is fixed mechanically so that it is locked at the middle position.

	▷Effect Improves fuel efficiency by approx. 1.7%. Expands the intake CVVT operating range. (Increases the retarded amount by up to 30° compared to the default state.) ∇ LIVC (Late Intake Valve Close) ∇ 1. Improves fuel efficiency by reducing pumping loss. 2. Improves knocking characteristics by reducing compression ratio.

Default position : Middle CVVT operates in advanced / retarded directions.

- Operation Principle The CVVT has the mechanism rotating the rotor vane with hydraulic force generated by the engine oil supplied to the advance or retard chamber in accordance with the CVVT oil control valve control.

• The variable force solenoid (VFS) changes its force depending on the PWM duty to control the stroke of the OCV.

• It also controls the lock, unlock, advanced, retarded, and holding functions.

[CVVT System Mode]

(1) Low Speed / Low Load	(2) Part Load

(3) Low Speed / High Load	(4) High Speed / High Load

Driving Condition	Exhaust Valve		Intake Valve
Driving Condition	Valve Timing	Effect	Valve Timing	Effect
(1) Low Speed/Low Load	Completely Advance	* Valve Under-lap * Improvement of combustion stability	Middle	* Valve Under-lap * Improvement of combustion stability
(2) Part Load	Retard	* Reduction of HC	Retard	* Reduction of pumping loss
(3) Low Speed /High Load	Completely Advance	* Reduction of pumping loss	Advance	* Prevention of intake back flow (Improvement of volumetric efficiency)
(4) High Speed/High Load	Completely Advance	* Reduction of pumping loss	Advance	* Prevention of intake back flow (Improvement of volumetric efficiency)

Evaporative Emission Control System

Engine Control / Fuel System

Other information:

Hyundai Accent (HC) (2017 - 2022) Service Manual: Emission control system

The emission control system on your Hyundai Accent is covered by a written limited warranty. Review the warranty details in the Owner’s Handbook & Warranty Information booklet supplied with the vehicle. Your Hyundai Accent is equipped with an emission control system designed to meet applicable emissions regulations. The system is made up of three main parts, as follows.

Hyundai Accent (HC) (2017 - 2022) Service Manual: Explanation of scheduled maintenance items

Engine Oil and Filter The engine oil and filter should be changed at the intervals specified in the maintenance schedule. If the Hyundai Accent is being driven in severe conditions, more frequent oil and filter changes are required to protect the engine from accelerated wear and sludge buildup. Drive Belts Inspect all drive belts for evidence of cuts, cracks, excessive wear or oil saturation and replace if necessary.

Catalytic Converter
CVVT (Continuously Variable Valve Timing) System