Variable Camshaft Timing (VCT) Operation
WARNING: This page is about a different car, the 2020 Jaguar XF and 2019 Jaguar XF. However, it is still accessible from the selected car via links, so may be relevant.
When the engine is running, the compression and expansion of the valve springs causes momentary increases and decreases in the torque acting on the camshafts. These momentary changes of torque are sensed in the VCT units and used to change the camshaft timing.
| ITEM | DESCRIPTION |
|---|---|
| A | Camshaft torque |
| B | Camshaft rotation (degrees) |
| C | Valve opening |
| D | Peak lift |
| E | Valve closing |
| 1 | 1000 rev/min |
| 2 | 4000 rev/min |
| 3 | 7000 rev/min |
| 4 | Inertia effects from valve train rotating components |
| 5 | Force caused by valve spring |
| 6 | Bias torque from friction |