Hyundai Santa Fe: Exhaust Emission Control System / CVVT (Continuously Variable Valve Timing) System. Description and operation

Hyundai Santa Fe (TM) 2019-2025 Service Manual / Emission Control System / Exhaust Emission Control System / CVVT (Continuously Variable Valve Timing) System. Description and operation

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 consist of

–	the CVVT Oil Control Valve (OCV) which supplies the engine oil to the cam phaser or runs 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 varies the cam phase by using the hydraulic force of the engine oil.

The engine oil getting out of the CVVT oil control valve varies 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.

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	Completely Retard	* Valve Under-lap * Improvement of combustion stability
(2) Part Load	Retard	* Increase of expansion work * Reduction of pumping loss * Reduction of HC	Retard	* Reduction of pumping loss
(3) Low Speed /High Load	Retard	* Increase of expansion work	Advance	* Prevention of intake back flow (Improvement of volumetric efficiency)
(4) High Speed /High Load	Advance	* Reduction of pumping loss	Retard	* Improvement of volumetric efficiency

Catalytic Converter. Repair procedures

Removal [Catalytic Converter (WCC)] 1. Remove the exhaust manifold. (Refer to Engine Mechanical System - "Exhaust Manifold") [Catalytic Converter (UCC)] 1...

Engine Control/Fuel System

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Hyundai Santa Fe (TM) 2019-2025 Owner's Manual: ISG system operation

Prerequisite for activation ISG system operates in the following situations. The driver's seatbelt is fastened The driver's door and hood are closed The brake vacuum pressure is adequate The battery sensor is activated and the battery is sufficiently charged Outside temperature is not too low or too high The vehicle is driven over a constant speed and stops The climate control system satisfies the conditions The vehicle is sufficiently warmed up ISG related parts are working properly The incline is gradual The steering wheel is turned less than 180 degrees and then the vehicle stops Information If the ISG light (white) is turned on on the instrument cluster and does not meet the ISG system operating conditions, the ISG system is not activated...