Variable valve control (VVC)

VARIABLE VALVE CONTROL (VVC)

Hydraulic control unit (HCU) Dependent on which solenoid is energised, a spool valve within the HCU dictates the position of the VVC mechanism.

Solenoids

Variable valve control is determined by the ECM which energises a solenoid in order to control the VVC mechanism. Only one solenoid will be energised at a time to either drive the VVC mechanism towards minimum cam period, or towards maximum cam period. The desired cam period is calculated by the ECM using engine speed and manifold pressure (engine load). The current cam period is measured by the ECM using the camshaft position sensor. The ECM then energises the correct solenoid in order to move the mechanism towards the desired position. The ECM controls solenoid 1 on the O/B wire and solenoid 2 on the O/K wire. Supply to the solenoids is on the N/K wires.

Oil temperature sensor The oil temperature measured by the sensor is fed to the ECM on the G/O wire and used to derive the viscosity of the oil passing through the hydraulic control unit which indicates how quickly the VVC mechanism will respond. Earth is on the K/B wire.