Camshaft Profile Switching (Cps) Control

The inlet camshaft has, in addition to the VCT control, a CPS function which is also controlled by the ECM. The CPS control can vary the valve lift height and duration of the camshaft lobes by adjusting the area of the hydraulic tappet which acts on one of two cam lobe profiles. The CPS control is via two CPS solenoid valves, located at each end of the inlet camshaft. The CPS solenoid valves control the position of hydraulic tappet assemblies which can be set in one of two positions; low and high.

Two CPS solenoids are used so that the hydraulic tappets can be adjusted when no load is applied, for example the cam lobes are off the hydraulic tappets and the cam base circle is acting on the tappet, this keeps the stress on components to a minimum. One CPS solenoid supplies oil pressure to the hydraulic tappets of cylinders 1, 2 and 4 and the second CPS solenoid supplies oil pressure to the tappets of cylinders 3, 5 and 6.

At engine start and at low engine oil temperatures (below 40°C (104°F)) the ECM does not direct engine oil pressure to the hydraulic tappets and therefore the hydraulic tappets are in their spring loaded, low position. Refer to ENGINE (I6 3.2L PETROL) .