Abstract: A method and device for delay-free measurement of the air/fuel ratio of combustion systems, especially internal combustion engines, by measuring individual components of the fuel, the ambient air used for fuel combustion, and the exhaust gas, wherein the water vapor concentrations of the exhaust gas and, preferably, the ambient air or the gas supplied for fuel combustion are measured, and wherein the air/fuel ratio are computed by the obtained values and data on fuel composition.

Abstract: In conventional methods of quantitative hydrocarbon analysis in gaseous sles by means of infrared transmission, systematic inaccuracies may be found which are caused by changes in the composition of the components contained in the sample. Such inaccuracies typically amount to 10 to 30% of the measured value, with occasional rises of up to 100%. In order to eliminate this disadvantage the invention proposes that for determining the total mass of gaseous and condensed hydrocarbons radiation be used with a frequency band whose integral infrared absorption has approximately the same value for each of the main hydrocarbons present.