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Home >> Kia >> 2019 >> Optima S >> Repair and Diagnosis (Single Page) >> Engine Mechanical >> Auxiliary Emission Control Systems >> Exhaust Emission Control System - 2.4L (Except HEV) >> CVVT (Continuously Variable Valve Timing) System >> Description & Operation >> Operation Principle >> CVVT System Mode

CVVT System Mode

G12932693Courtesy of KIA MOTORS AMERICA, INC.
G12932694Courtesy of KIA MOTORS AMERICA, INC.
Driving Condition Exhaust Valve Intake Valve
Valve Timing Effect Valve Timing Effect
(1) Low Speed/Low Load Completely Advance
  • * Valve Under-lap
  • * Improvement of combustion stability
  • * Increase of expansion work
 Completely Retard
  • * Valve Under-lap
  • * Improvement of combustion stability
(2) Part Load Retard
  • * 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
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