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Home >> Kia >> 2012 >> Forte EX, 4D Hatchback, Automatic Trans >> Repair and Diagnosis >> Engine Mechanical >> Auxiliary Emission Control Systems >> Exhaust Emission Control System >> CVVT (Continuously Variable Valve Timing) System >> Description and Operation >> (CVVT System Mode)

(CVVT System Mode)

Fig 1: CVVT System Mode Graph
G07367768Courtesy of KIA MOTORS AMERICA, INC.
Fig 2: CVVT System Mode Graphs
G07367769Courtesy of KIA MOTORS AMERICA, INC.
DRIVING CONDITION FOR INTAKE AND EXHAUST VALVES

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
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