NOVELTY - The method involves changing the engine operating mode from a lean fuel/air mix to a rich fuel/air mix and then using a supplemental torque apparatus (34) that is operatively connected to the engine to convert a proportion of the engine torque, which is increased by the change in engine operating mode, into energy which can be stored and then later controllably released.    USE - For controlling torque in direct injection engines that have a lean NOx trap in the exhaust system and a supplemental torque apparatus operatively connected to the engine.    ADVANTAGE - The method enables lean NOx tanks to be purged while avoiding any undesirable engine torque disturbances. A supplemental torque apparatus is a faster actuator than using the electronic throttle, has a direct influence on engine torque and is more suitable for torque mitigation than using the throttle. Engine operation at higher loads is more efficient, at least for homogenous operation during the purge mode, than it would be using the throttle to control torque and efficiency is also gained due to reduced pumping losses when the throttle is open. The extra energy generated during the purge mode is stored for future use during the lean mode and the use of a supplemental torque apparatus for torque management frees up spark time for emission control.    DETAILED DESCRIPTION - The method involves the time for purging the lean NOx trap (LNT) (26), determining the state of charge in the vehicle battery (38) and changing the operational mode of the engine from lean to a rich air/fuel ratio, with the change resulting in an increased engine torque. The LNT is purged by the increased fueling rate of the rich air/fuel ratio and the increased engine torque is converted into energy by controlling the output of a supplemental torque apparatus operatively connected to the supplemental torque apparatus and used to charge the vehicle battery instead of being used on the engine crankshaft, so that the desired torque output of the engine is maintained during the purging step. The operational mode of the engine is changed back from a rich to a lean air/fuel ratio and the stored energy is controllably released. The supplemental torque apparatus may be formed from an alternator-starter that is connected to the output shaft of the engine and to a battery or alternatively the engine may be a hybrid engine with the supplemental torque apparatus acting to apply regenerative braking.    INDEPENDENT CLAIMS are included for:    (1) A system for torque control for a lean burn engine,    (2) A supplemental torque apparatus for a lean burn engine.    DESCRIPTION OF DRAWING(S) - A schematic diagram of an engine suitable for using the torque control method.    Lean NOx trap (26)    Supplemental torque apparatus (34)    Battery (38)