A system for an engine has an upstream emission control device with a washcoat
having a predetermined amount of precious metal disassociated with NOx storage
material, where the upstream emission control device in a close coupled location
to an exhaust manifold of the engine. The system also includes a downstream emission
control device coupled to the upstream emission control device. Further, a controller
is used for operating the engine lean with retarded ignition timing to generate
heat and raise temperatures of said upstream and downstream emission control devices.
The controller also determines whether temperature of said upstream device has
reached a predetermined value, and in response to said determination, operates
the engine rich at least to reduce NOx stored in said upstream emission control
device during said lean operation.