Driving - Manual/Sport mode (Automatic gearbox - EM-CVT)

As the vehicle speed increases, higher ratios are required. As engine speed increases the fluid pressure generated by the pump increases. This increase in pressure is felt by the primary pulley cylinder which moves to gradually move the pulley sheaves together increasing its effective diameter.

Simultaneously, the secondary pulley sheaves move apart, reducing its diameter and increasing the gearbox ratio. When the primary pulley is closed and the secondary pulley is fully open, the gearbox operates in an overdrive ratio, with the secondary pulley rotating at approximately two and a half times the speed of the primary pulley.

When kickdown is required, the ECM transmits a message to the GIU to control the ratio control motor accordingly. The GIU adjusts the ratio control motor which, in turn, moves the hydraulic control valve to lower the gearbox ratio to achieve the required acceleration.

Driving - Manual/Sport mode

In manual/sport mode the gearbox functions as a conventional CVT unit or a semi-automatic manual transmission. In sport mode, the engine speed is higher under all driving conditions which gives improved acceleration.

By moving the selector lever to the + or - position, or pressing a steering wheel switch, the system is commanded to operate in manual mode. If required, the driver can make sequential gear selections using either the selector lever or the steering wheel mounted switches.

The ratio control motor operates to match the gear ratio to the target engine speed. In any mode, the motor position is varied to provide the ’kickdown’ function of a conventional automatic transmission.

In manual mode, the position of the ratio control motor is varied to control engine speed, fixing the current gear ratio. The action of the motor operates the hydraulic control unit to adjust the primary pulley.

The GIU checks if a requested gear change made by the driver is permitted. Gear changes will be ignored if the driver requests a change which is dangerous or could damage the transmission.

If a shift up is required and the driver has not made the required selection using the selector lever or the steering wheel switches, the next higher gear will be selected when the engine speed reaches maximum rev/min.

If the driver does not make a required shift down when the vehicle is slowing, the next lower gear will be selected automatically. The LCD in the instrument pack will always display the current gear.

Manual/sport mode is deselected by moving the selector lever back to the ’D’ (automatic) position.

Fast Adaptation Procedure

When a new gearbox is fitted, the ECM replaced or ECM EEPROM re-initialised by TestBook, the ECM needs to learn the positions of the ratio control motor for given engine speeds.The ECM will target twelve engine speeds between 1400 and 4500 rev/min in order to achieve fast adaptation.

Fast adaptation is performed as follows:

WARNING: Ensure that all road tests are conducted by suitably qualified drivers in a safe and legal manner, and where local traffic conditions allow.

• With the selector lever in position ’D’, accelerate the vehicle up to 35 mph (55 km/h), then release the accelerator pedal and allow the vehicle to decelerate without braking.
• As the vehicle decelerates, the ECM will learn the ratio control motor adaptation points. This procedure should be complete before the vehicle stops moving.
• If the gearbox reaches its lowest ratio before the adaptation is complete, the engine speed will drop from the target speed to idle.
• To complete the procedure, accelerate up to a speed of more than 25 mph (40 km/h) and release the accelerator pedal again. Allow the vehicle to decelerate without braking to enable the ECM software to learn the remaining adaptation points.
• Fast adaptation is complete when the ’F’ in the instrument pack LCD stops flashing and only the mode is displayed.

The ECM software continuously adapts to account for gearbox wear and fast adaptation errors. The driver will not be aware that any adaptation is taking place and normal driving will be maintained.