KIA Niro: Variable Force Solenoid (VFS)

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 Variable Force
Solenoid (VFS) which supplies the engine oil to the cam phaser or cuts the engine oil from the cam
phaser in accordance with the ECM PWM (Pulse With Modulation) control signal, the Cam Phaser
which varies the cam phase by using the hydraulic force of the engine oil.Variable force solenoid (VFS) (intake) changes its force depending on the PWM duty to control the stroke of the CVVT oil
control valve (OCV) (intake) bolt. The delivered oil rotates the rotor connected to the camshaft of the
cam pager and rotates the camshaft to the engine rotating direction (intake advanced / exhaust
retarded) or the opposite direction (intake retarded / exhaust advanced) to change the phase angle of the cam.

Variable Force Solenoid (VFS) (Bank 1 / Intake)

Circuit Diagram

Harness Connector

Variable Force Solenoid (VFS) Repair procedures

Removal

1. Turn ignition switch OFF and disconnect the battery negative (-) terminal
2. Disconnect the VFS connector (A).
3. Remove the mounting bolts (B), and then remove the VFS from the engine.

Variable force solenoid mounting bolt : 9.8 - 11.8 N*m (1.0 - 1.2 kgf*m, 7.2 - 8.7 lb*ft)

Installation

Warning

• Install the component to the specified torque.
• Note that internal damage may occur when the component is dropped. If the component has been dropped, inspect before installing
• Do not use any dropped variable force solenoid (VFS) valve.
• Note below cautions when installing variable force solenoid (VFS) valve.

1) After replacing the O-ring (A) of variable force solenoid (VFS) valve, apply engine oil on new O-ring (A).

2) Push variable force solenoid (VFS) valve up to the timing chain cover, and temporarily tighten the bolt.

3) Tighten the variable force solenoid (VFS) valve to the specified torque.

1. Install in the reverse order of removal.

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