Patent ID: 6931837

Claim:
A control method for lean-to-rich modulation of an internal combustion engine comprising: with the engine running lean at a particular speed, causing the engine to transition from running lean to running rich while striving to maintain a desired engine torque at that particular speed by a) processing data values for engine speed and desired engine torque to develop a data value for desired mass airflow into the engine and a data value for desired air-fuel ratio for rich running, b) processing the data value for desired air-fuel ratio for rich running, a data value for actual mass airflow into the engine, and a data value for actual air-fuel ratio to develop a data value for quantity of engine fueling, c) processing the data value for quantity of engine fueling and other data relevant to a determination of the timing of introduction of that quantity of engine fueling into the engine during an engine cycle that will cause the engine to run rich while striving to maintain desired engine torque at the particular engine speed, to develop a data value for that timing, d) forcing intake mass airflow toward that desired mass airflow, and e) fueling the engine with that quantity of engine fueling at that timing.