Method and device for operating an internal combustion engine having lambda control

A method of operating an internal combustion engine, with which a lambda controller is associated, the lambda controller being designed to generate a controller control signal in the form of a correction contribution as a function of an actual value of an air-fuel ratio in a combustion chamber and upon a predefined setpoint value of the air-fuel ratio in the combustion chamber, and which comprises an intake tract and an exhaust gas tract, which as a function of a switching position of at least one gas inlet valve and at least one gas outlet valve respectively communicate with the combustion chamber of a cylinder, and which comprises one injection valve per cylinder for metering a fuel mass into the combustion chamber of the corresponding cylinder, as a function of a control signal that is determined as a function of the correction contribution,

• the method comprising the steps of:
• as a function of at least one operating variable, determining an operating state of the internal combustion engine, which comprises a cold operating state and a warm operating state of the internal combustion engine, and
• in the active state of the lambda controller,
• in the cold operating state and given the existence of a predefined first condition
• determining a current cold adaptation value as a function of at least one component of the controller control signal, a valid cold adaptation value and a valid warm adaptation value,
• assigning the current cold adaptation value to the valid cold adaptation value,
• in the warm operating state and given the existence of a predefined second condition
• determining a current warm adaptation value as a function of at least the component of the controller control signal and the valid warm adaptation value,
• adapting the valid cold adaptation value given the existence of a predefined third condition as a function of a difference between the valid warm adaptation value and the current warm adaptation value,
• assigning the current warm adaptation value to the valid warm adaptation value, and
• in the cold operating state, determining the control signal as a function of the valid cold adaptation value and the valid warm adaptation value and in the warm operating state, determining the control signal as a function of the valid warm adaptation value.