A method for controlling the combustion of a spark-ignition internal-combustion engine, wherein at least one signal representative of a state of the combustion is recorded by means of at least one detector arranged on the engine, characterized in that it comprises: - selecting indicators of the combustion that can be deduced from said signal and defining a multidimensional space each dimension of which corresponds to one of said indicators, and wherein any combustion can be represented by a point, - defining in said space a closed surface so as to surround points corresponding to normal combustions and not to surround points corresponding to abnormal combustions due to pre-ignition, defining said closed surface by carrying out the following steps: • selecting an equation defining said surface, said equation comprising at least one parameter, • carrying out a set of combustions wherein normal combustions and abnormal combustions are known, and representing said set of combustions in said multidimensional space forming a cluster of points, • determining, by means of a principal component analysis, principal directions of said cluster of points, and determining a dispersion of the points in each principal direction, • modifying said parameter so that the extension of the surface in each principal direction is equal to the dispersion in this direction; then, for each combustion of an engine cycle: - representing said combustion of the cycle by a point in said multidimensional space by determining for this combustion said indicators, - determining a position of said point with respect to said surface and deducing therefrom an abnormal nature of said combustion, - determining a distance between said point and said surface, and deducing therefrom a severity of the abnormal nature, and - controlling the progress of the abnormal combustion detected as a function of the severity of the abnormal nature. - selecting indicators of the combustion that can be deduced from said signal and defining a multidimensional space each dimension of which corresponds to one of said indicators, and wherein any combustion can be represented by a point, - defining in said space a closed surface so as to surround points corresponding to normal combustions and not to surround points corresponding to abnormal combustions due to pre-ignition, defining said closed surface by carrying out the following steps: • selecting an equation defining said surface, said equation comprising at least one parameter, • carrying out a set of combustions wherein normal combustions and abnormal combustions are known, and representing said set of combustions in said multidimensional space forming a cluster of points, • determining, by means of a principal component analysis, principal directions of said cluster of points, and determining a dispersion of the points in each principal direction, • modifying said parameter so that the extension of the surface in each principal direction is equal to the dispersion in this direction; • selecting an equation defining said surface, said equation comprising at least one parameter, • carrying out a set of combustions wherein normal combustions and abnormal combustions are known, and representing said set of combustions in said multidimensional space forming a cluster of points, • determining, by means of a principal component analysis, principal directions of said cluster of points, and determining a dispersion of the points in each principal direction, • modifying said parameter so that the extension of the surface in each principal direction is equal to the dispersion in this direction; - representing said combustion of the cycle by a point in said multidimensional space by determining for this combustion said indicators, - determining a position of said point with respect to said surface and deducing therefrom an abnormal nature of said combustion, - determining a distance between said point and said surface, and deducing therefrom a severity of the abnormal nature, and - controlling the progress of the abnormal combustion detected as a function of the severity of the abnormal nature.