Originally Posted by norbert
Thats not strictly true, the Variator not functioning correctly will affect performance, particularly above 5k revs.
IT'S THE OPPOSITE!!!
The variator is called into action on low and medium revs, to provide extra torque. It's not in use in high revs at all!!!
Transcription from eLearn Workshop Manual:
Controlled directly by the fuel injection control unit, the purpose of the timing variator is to vary the timing of the inlet valves in accordance with the engine load and required rpm.
OPERATION IN CLOSED STAGE (FC)
When the closed stage is required (idle speed and maximum power zone)
, the solenoid (1) is de-energized, so the slide valve (2), pushed by the return spring (3), remains raised, preventing the oil coming from the duct (A) from reaching the variator.
In this case the timing of the inlet valves remains unchanged
OPERATION IN OPEN STAGE (FA)
When the open stage is required (medium rpm with high torque)
. The solenoid (1) is energized, thus pushing the slide valve (2) downwards.
In this position, the oil coming from the duct (A) enters the chamber (B) of the piston, and from here, through a special hole, goes into the duct (C) in the piston.
The oil can only emerge from this duct through the top hole (in communication with the delivery pipe (D) to the variator), since the bottom hole, as the slide valve (2) has lowered, is not in communication with the discharge pipe (E).
The oil passes through the duct (D) and (F) and reaches the chamber (G), pushing in an axial direction towards the engine the piston (4), which comprises outer helical teeth, forcing it to rotate clockwise.
Its rotation is transmitted via a straight-teeth splined profile to the pinion (5) which, screwed onto the threaded end of the camshaft (6), transmits rotation to the camshaft, thus varying by 25° engine the timing of the inlet valves
When the solenoid is de-energized, the slide valve (2) returns to its initial position, cutting off the flow of pressurized oil to the piston (4), but allowing oil to return to the discharge, thanks to the force of the return spring (7).
The duct (D) lubricates the camshaft journal in the various operating conditions.
The oil which leaks into the chamber (H) of the solenoid is discharged through the drain duct (E).