Closely coupled exhaust catalyst system and engine strategy associated

Abstract

A catalytic converter having a first highly loaded palladium or trimetal catalytic element containing palladium of relatively large particle size closely coupled to the engine exhaust manifold, followed by one or more second catalytic elements having high oxygen storage capacity to provide protection against warmed-up engine emissions break through, is efficient in reducing cold-start emissions through early catalyst light-off. The catalytic converter is advantageously used in conjunction with an engine strategy employing oscillative spark retard during warm up to further reduce catalyst light-off and transient spark advance dampening to eliminate spiking of HC and CO during engine transients. When employed in conjunction with secondary air injection, the engine EEC is programmed to delay air injection for a period following cold-start sufficient to assure that catalyst light-off is rapidly attained.