US Patent 7617812 Method of operating a compression ignition engine

It relates to a method of operating a compression ignition engine comprising:—determining an instantaneous driver torque demand;selectively operating the engine in a first mode or a second mode dependent on the rate of change of driver torque demand;said first mode comprising an air lead mode whereby the intake air flow rate is controlled to achieve the instantaneous driver torque demand and an amount of fuel injected is controlled to obtain a target air/fuel ratio based upon said intake air flow rate;said second mode comprising a fuel lead mode wherein the amount of fuel injected is controlled to achieve the instantaneous torque demand.