Comparative analysis of closed loop AFR control during cold start

This paper examines the air-fuel ratio (AFR) control of the spark-ignited, internal combustion engine during cold start. It has been shown that a significant amount of emissions occur during cold start and idle before the AFR closed-loop control system goes into effect. Use of combustion pressure feedback, as measured from within the engine cylinder, is investigated for AFR control during cold start in an attempt to achieve better emissions. Specifically, the combustion pressure is used to calculate the equivalent heat release duration, which is then used for feedback control. Linear and nonlinear control techniques are applied to a Ford V8 engine in a laboratory setting, and the results are compared