Overboost function

Fig 1: Identifying Overboost Function

Courtesy of SAAB-SCANIA OF AMERICA, INC.

To further increase the engine torque during fast acceleration, for example, cars with engine alternative B235R and manual gearbox have a function called "OVERBOOST ".

The overboost function enables the engine torque to be higher than the normal values programmed in the Trionic control module memory. The normal value is max. 350 Nm in the speed range 1900-4000 RPM, but during powerful acceleration when the overboost function is activated, the control module will change to another value that allows a higher max. torque (370 Nm in the same speed range). The overboost function gives an increase in torque in all speed ranges, although the increase is greatest in the range 1900-4000 RPM.

The time in which the overboost function is allowed to be active is 20 seconds, after which the control module will return to the normal engine torque curve. The time for overboost is maximized to 20 seconds to reduce the thermal strain on the engine.

After using overboost for a period of 20 seconds the control module will use the normal engine torque curve for 10 seconds. This to give the engine a chance to cool down before a new period of overboost is allowed.