Lean Automotive Engine Operation - Hydrocarbon Exhaust Emissions and Combustion Characteristics

Some of the major factors contributing to cycle-to-cycle combustion variations in an automotive engine have been determined over a wide range of air-fuel ratios. The combustion variations lead to a general degradation of the combustion processes at very lean air-fuel ratios, which, in turn, places limits on operating an engine very lean to achieve low exhaust emissions.