Method of controlling an engine during transient operating conditions

A method of controlling an engine (20) having a mechanically driven supercharger (24) supplying a flow of air to the engine (20) includes defining a steady state operating condition in which the engine (20) normally operates within efficiently. An engine (20) parameter is monitored to determine if the engine (20) is operating within the steady state operating condition, or outside the steady state operating condition in a transient operating condition. If the engine (20) is operating outside the steady state operating condition in the transient operating condition, the flow of air from the supercharger (24) is adjusted to maintain a fuel/air mixture to within a pre-determined ratio prior to increasing a fuel injection rate to the engine (20) to minimize soot emissions from the engine (20) during operation of the engine (20) in the transient operating condition.