Self-Diagnostics Feature: Adaptions

The fuel-air mixture formed in the intake tract requires a certain period of time until it reaches the oxygen sensor in the form of exhaust gas. This time decreases as load and engine speed increase. For this reason, the response time of the emission control system is also dependent on load and engine speed. Fuel-air mixture deviations detected by the oxygen sensor result in storage of adaption values (learned correction values) by way of the adaptions, the injection can be brought close to the nominal values in advance. A reduction in the response time is achieved in this way. For instance, if the basic injection values of the DME characteristics map are too low during idling in order to maintain the ideal fuel-air mixture, the emission control system would have to constantly increase the injection timing. In this case, an adaption value is learned which corrects the basic injection value. The emission (lambda) control then only needs to undertake the fine adjustment.