Patent ID: 6843051

Claim:
A method for controlling the operation of an internal combustion engine in a motor vehicle, wherein the engine generates exhaust gas including at least a first and a second exhaust gas constituent, and wherein exhaust gas is directed through an emissions control device before being exhausted to the atmosphere, the device storing at least the first exhaust gas constituent when the exhaust gas directed through the device is lean of stoichiometry and releasing previously-stored first exhaust gas constituent when the exhaust gas directed through the device is rich of stoichiometry, the method comprising: during a rich engine operating condition, determining a value related at least in part to the presence of the exhaust gas constituent in the exhaust gas downstream of the device; calculating the difference, if any, by which the determined value exceeds a predetermined value; accumulating the difference; and discontinuing the rich engine operating condition when the accumulated difference exceeds a predetermined value.