Patent ID: 7181905

Claim:
A method for controlling engine operation in a vehicle, the engine coupled to an emission control device including at least platinum particles for converting emissions from the engine, the method comprising: detecting a deceleration condition of the vehicle; in response to said deceleration condition, adjusting fuel injection into the engine to maintain an exhaust mixture air-fuel ratio entering the emission control device to be lean, but less lean than a limit air-fuel ratio value, said limit air-fuel ratio value being a lean air-fuel ratio limit determined as a function of exhaust temperature, wherein said limit air-fuel ratio decreases as temperature increases, at least in one operating region, wherein said exhaust temperature includes temperature of the emission control device, wherein a second emission control device is coupled upstream of said emission control device wherein said limit air-fuel ratio for said downstream emission control device is based on an amount of oxygen storage of said upstream emission control device.