Patent ID: 7387116

Claim:
A method for operating a piston engine ( 1 ), in particular in a motor vehicle, whereby the piston engine ( 1 ) has a plurality of cylinders ( 6 ) having intake valves ( 9 ), exhaust valves ( 10 ), combustion chambers ( 7 ) and pistons ( 8 ) adjustable therein, whereby the piston engine ( 1 ) has a fresh gas system ( 2 ) for supplying fresh gas to the combustion chambers ( 7 ), the system comprising at least one extra valve ( 13 ) which is assigned to one or more or all the cylinders ( 6 ), whereby the piston engine ( 1 ) has a fuel system ( 5 ) for supplying fuel to the combustion chambers ( 7 ), whereby the piston engine ( 1 ) has an exhaust system ( 4 ) for removing exhaust gas from the combustion chambers ( 7 ), wherein a fuel/fresh gas ratio (λ) is measured in the exhaust gas selectively for each cylinder in the exhaust system ( 4 ), the fuel system ( 5 ) is operated so that it supplies the same quantity of fuel to all combustion chambers ( 7 ) in a steady-state operating state of the piston engine ( 1 ), the extra valve ( 13 ) is or the extra valves ( 13 ) are operated so that in steady-state operation of the piston engine ( 1 ) the quantity of fresh gas supplied to the combustion chambers ( 7 ) is adjusted selectively for each cylinder as a function of the measured fuel/fresh gas ratio (λ actual ) to achieve a target value (λ setpoint ) for the fuel/fresh gas ratio (λ) that is the same for all cylinders ( 6 ).