Patent ID: 7272487

Claim:
A method for monitoring combustion stability of an internal combustion engine including a crankshaft, an intake manifold and at least one cylinder, and an exhaust gas recirculation system, the method comprising: calculating an absolute deviation of an engine parameter with respect to its actual set point; determining combustion stability based on a comparison of said deviation to a predetermined threshold, wherein said predetermined threshold is stored in at least one lookup table using at one of least engine load and engine speed as scheduling variables, so that said threshold is read out from said at least one lookup table by using said scheduling variables as input data; and decreasing an exhaust gas mass fed into the intake manifold when combustion is not stable in order to decrement a burnt mass fraction Fi present in the cylinder charge by a specific value ΔFi which is stored in at least one lookup table using at least one of engine load and engine speed as scheduling variables, so that said value is read out from said at least one lookup table by using said scheduling variables as input data.