Continuously Variable Valve Lift Solenoid

The non-serviceable variable valve lift assembly comprises four continuously variable valve lift solenoids which are responsible for the control of the intake valve lift.

The continuously variable valve lift system converts the camshaft motion into the valve lift through the use of a hydraulic circuit. The variable valve lift system can adjust the valve lift through the use of the oil flow.

The intermediate hydraulic chambers open the valves by means of oil pressure. The oil is allowed to flow to the chambers that actuate the valves dependent on whether a solenoid is actuated or not.

Opening and closing of the solenoid allows the operation of the variable valve lift system in the following four different lift modes:

• Full lift mode - The valves are fully opened and closed as normal. The valves are controlled by the camshaft profile. This mode is used at high engine speeds to obtain maximum engine power.
• The late intake valve opening mode - The opening of the intake valves are delayed when starting the engine and during idling. The valves open for a shorter period and at a lower lift providing precise control of the exact amount of air entering the cylinder. As a result fuel economy is improved during idling periods. During a cold start, only a small amount of cold air enters the cylinder, meaning the engine starts more easily.
• The early intake valve closing mode - The intake valves are closed hydraulically before the camshaft profile would normally allow. This reduces pumping losses, increases the engine output per liter and prevents an undesirable backflow of the fuel mixture into the intake ports.
• Composite mode - A combination of the late intake valve opening mode and the early intake valve closing mode.

The continuously variable valve lift solenoid is controlled by the Powertrain Control Module (PCM) with Pulse Width Modulated (PWM) signal.