Mixture adaptation

The mixture formed in the intake area requires some time before it reaches the oxygen sensor as exhaust emissions. This time decreases as load and engine speed increase. For this reason, the response time of the oxygen sensor emissions control is also load-dependent and speed-dependent. The mixture deviations detected by the oxygen sensor lead to the system saving adaptation values (taught-in correction values). The adaptations are intended to bring the injection close to the setpoint value in advance. A reduction in the response time is achieved in this way.

For example, if the basic fuel injection values of the engine control unit characteristic map are too low at idle speed to maintain the ideal fuel-air mixture, the oxygen sensor emissions control would have to continuously increase the injection period. In this case, an adaptation value is learnt which corrects the basic injection value. The oxygen-sensor control then only needs to undertake the fine adjustment.