A method for controlling diesel engine emissions is disclosed. The diesel engine's exhaust system has a diesel particulate filter (DPF) and a lean NO.sub.x trap (LNT). The DPF is a filter and is monitored to determine the need for regeneration. The LNT is monitored to determine the need for regeneration or desulfurization. A fuel injector is used to inject fuel upstream of the LNT under certain conditions, and a bypass may be used to bypass exhaust around the DPF to provide richer or hotter exhaust to the LNT. The sensor outputs and controls for providing the appropriate heat or fuel mix for regeneration and desulfurization may be controlled with enhancements to existing engine control circuitry.
Magdi K. Khair; Cynthia C. Webb; Gordon J. Bartley; Christopher A. Sharp