Description And Operation: Description

Variable Intake manifold Solenoid (VIS) valve is installed on the intake manifold.
The VIS valve controls the vacuum modulator which activates a valve in the intake manifold.
The ECM opens or closes this valve according to engine condition (Refer to below table).

Courtesy of KIA MOTORS AMERICA, INC.

Engine condition	VIS valve	Operation
Medium speed	Closed	Increasing engine performance in low engine speed by reducing intake interference among cylinders
Low/High speed	Open	Minimizing intake resistance by shortening intake manifold length and increasing area of air entrance

Courtesy of KIA MOTORS AMERICA, INC.