Engine Torque

Engine torque

The actual air mass/combustion is converted to torque, unit Nm. This information is sent continuously on a bus and TCM uses the information to control the system pressure.





Diagnostics
If the function is faulty a diagnostic trouble code is generated in the engine system.

If bus communication with the engine control system has ceased a P1921 diagnostic trouble code is generated, the gearbox goes into the limp-home mode.

Inaccurate information on the bus causes diagnostic trouble code P1971 to be generated. Depending on the fault, the TCM may activate the emergency operation program (Limp-Home mode).












In order to achieve smoother gear changes and minimal gearbox wear, the TCM continuously sends information on the bus to the engine control system about the "maximum torque" in Nm.

As the gearbox is constructed to withstand a maximum torque of 350 Nm (B235), >310Nm (B235E, B308E) and >280 Nm (B205E, D223L), the TCM normally transmits the bus information "Maximum torque 350/330 Nm" but during certain gear changes, especially during hard acceleration, the TCM requests a lower "maximum torque" during the short gear change interval.

The engine control system uses the information for torque limiting via air mass control.