Patent ID: 7891170

Claim:
A method for controlling an internal combustion engine having an intake tract, an exhaust tract incorporating a three-way catalytic converter, and a cylinder connected to the intake tract via a gas inlet valve and connected to the exhaust tract via a gas outlet valve, an injection valve that meters-in fuel to the cylinder, and a post-cat oxygen sensor disposed in the exhaust tract downstream of the three-way catalytic converter, comprising: determining a mass of fuel supplied to the cylinder as a function of a load variable; measuring a post-catalytic converter exhaust gas by the post-cat oxygen sensor; generating a post-cat oxygen sensor measurement signal; comparing the post-cat oxygen sensor measurement signal with a characteristic post-cat oxygen sensor measurement signal representing a predefined residual oxygen component; determining if the generated post-cat oxygen sensor measurement signal is representative of the characteristic post-cat oxygen sensor measurement signal based on the comparison; if the generated post-cat oxygen sensor measurement signal is determined to be representative of the characteristic post-cat oxygen sensor measurement signal: calculating a gradient of the post-cat oxygen sensor measurement signal based on at least two values of the post-cat oxygen sensor measurement signal; and determining an individual mass of fuel metered-in to the cylinder as a function of the calculated gradient of the at least two values of the post-cat oxygen sensor measurement signal; determining a corrected mass of fuel supplied as a function of: the mass of fuel supplied, and the individual mass of fuel metered-in if the generated post-cat oxygen sensor measurement signal is determined to be representative of the characteristic post-cat oxygen sensor measurement signal: and generating an actuating signal that controls the injection valve as a function of the corrected mass of fuel supplied.