Patent ID: 7251557

Claim:
A computer readable storage device having stored therein data representing instructions executable by a computer to implement a compression ignition for an internal combustion engine, the engine having a piston disposed in a cylinder to define a combustion chamber, intake valves for admitting fresh air into the cylinder, a fuel injector for injecting fuel into the combustion chamber, exhaust valves for discharging exhaust gas resulting from combustion within the cylinder, wherein opening and closing timings of the intake means and opening and closing timings of the exhaust means are adjustable, and sensors for measuring an actual λ-value for the exhaust gas and at least one further engine operating parameter, the computer readable storage device comprising: instructions for adjusting opening and closing timings of the intake means and opening and closing timings of the exhaust means such that the piston reciprocates within the cylinder to perform an exhaust phase, an exhaust gas retaining phase, an intake phase, a compression phase, and an expansion phase; instructions for providing a first start time of a first fuel injection by the fuel injector during said exhaust gas retaining phase and a second start time of a second fuel injection by the fuel injector during said exhaust gas retaining phase; instruction for selecting a λ-value from a map stored in the control unit, which value is a function of engine load and engine speed; instruction for determining a difference the actual λ-value what the selected λ-value; and instruction for adjusting the intake manifold pressure as a function of the difference between the said λ-values in order to obtain the selected λ-value.