Calculation, engine torque
Engine torque is primarily calculated using air mass per combustion and engine speed. But, ignition timing and current lambda value also affect the torque calculation. Retarded ignition timing generates lower engine torque. This is the case in knock control. As regards the lambda value, there is an optimal lambda value for each operating point. If the engine runs richer or leaner than the optimal value, engine torque reduces.
Note that a lambda value lower than the optimal value (richer mixture) produces lower torque.
The calculation also takes into account the torque used by the engine itself, i.e. the internal friction. Values for air mass, engine speed, coolant temperature and idling torque are used for this calculation.