Abstract: The present invention relates to a method for monitoring combustion stability of an HCCI internal combustion engine equipped with a crankshaft, an intake manifold and at least one cylinder, wherein stability is determined based on a deviation of an engine operating parameter such as, for example engine load or engine speed, from a predetermined threshold.

Abstract: The present invention relates to a method for monitoring combustion stability of an internal combustion engine equipped with a crankshaft, an intake manifold and at least one cylinder, including the following steps: determining the absolute deviation e of indicated mean effective pressure pind or indicated torque Tind with respect to their actual set point, i.e., with respect to actual indicated mean effective pressure set point pind,setpt or actual indicated torque set point Tind,setpt, namely ?pind or ?Tind, or alternatively determining the relative change ?e in said deviation between two consecutive combustion cycles k, k+1 of said at least one cylinder, i.e., determining (?pind,k+1?pind,k) or (?Tind,k+1??Tind,k) or determining the relative change ?e in angular acceleration ?? of the crankshaft between two consecutive combustion cycles k, k+1, i.e.