F 150 2WD Pickup V8-4.6L (2002)
Variable Cam Timing (VCT) Solenoid Valve
The VCT solenoid valve (Figure 128) is an integral part of the VCT system. The solenoid valve controls the flow of engine oil to the variable cam
timing unit assembly. As the PCM duty cycles the solenoid valve, oil is allowed to flow to the VCT unit assembly and advance or retard the cam
timing.
Variable Cam Timing (VCT) Unit Assembly
Variable Cam Timing Unit Assembly
The variable cam timing unit assembly (Figure 129) is coupled to the camshaft through a helical spline in the VCT unit chamber. When the flow of
oil is shifted from one side of the chamber to the other, the differential change in oil pressure forces the piston to move linearly along the axis of
the camshaft. This linear motion is translated into rotational camshaft motion through the helical spline coupling. A spring installed in the chamber
is designed to hold the camshaft in the minimum overlap position (5 degrees) when oil pressure is too low to maintain adequate position control.
The camshaft is allowed to rotate up to 30 degrees.
