Patent ID: 8874352

Claim:
A method of controlling the combustion phase of a fuel mixture of a spark-ignition supercharged internal-combustion engine, notably of gasoline type, wherein the engine comprises at least one cylinder with a combustion chamber, at least one fuel supply means, at least one intake means, at least one exhaust means and spark ignition means, characterized in that the method comprises, for high loads and low speeds of said engine: during the combustion of the fuel mixture, determining a crank angle value (θ′) where the maximum cylinder pressure (P max ) occurs in the combustion chamber, comparing the value thus determined with a maximum angle threshold value (θ max ) representative of an abnormal combustion in said chamber, detecting the start of an abnormal combustion when the determined value reaches said threshold value and when the ignition means are not actuated, and feeding an amount of another fuel into the fuel mixture in order to vary the global octane number of this fuel mixture so as to reduce the crank angle where the maximum cylinder pressure occurs.