Cycle-by-Cycle Gasoline Engine Cold Start Measurement of Residual Gas and AFR Using a Fast Response CO&CO ₂ Analyzer

A short study has been conducted to measure both AFR and residual gas fraction on a cycle-by-cycle basis for a gasoline engine during cold start and during a throttle transient. In-cylinder and exhaust port measurements were recorded using a fast response NDIR instrument to provide some insight in to the dynamic processes involved during these important transient engine conditions. The CO&CO₂ results are presented showing evidence of the large cyclic variability of fuel delivery during the first few firing cycles of the start. Misfires are also identified. A description of a post-processing tool is discussed for conversion of this data to AFR. It is hoped that this measurement method will be valuable to engine researchers and calibrators as a tool to understanding and lowering cold start and throttle transient HC and CO emissions as well as validating internal EGR models.