Patent attributes
The invention concerns a method for determining the composition of a fuel mixture from a first and at least a second fuel for operating a combustion engine, whereby the fuel mixtures of different compositions require various air/fuel ratios to achieve a stoichiometric combustion. Thereby it is provided that the air volume that has been delivered to the combustion engine, the fuel quantity that has been delivered and the oxygen content in the exhaust gas of the combustion engine are determined during one or several stationary operating phases of the combustion engine during one or several measuring phases, and in that the composition of the fuel mixture is determined from these values. The procedure allows an accurate and reliable determination of the composition of a fuel mixture for combustion engines that are operated in flex-fuel-mode.