Measurement of Cycle-by-Cycle AFR using a Fast Response NDIR Analyzer for Cold Start Fuelling Calibration Applications

This paper examines cold start of a gasoline PFI engine using a fast λ (normalised AFR) measurement technique. The technique uses established fast gas sensing equipment and post-processing calculations to obtain λ with a response time T_90-10% of 8ms.

The fast λ is compared with UEGO data. Known characteristics of the UEGO include slower T_90-10% and output errors when subjected to high quantities of HC; the new technique is shown to avoid these issues.

Five cold starts are performed. Fast λ can resolve each cycle. Differences were seen between the UEGO and fast λ and these are attributed to the characteristics mentioned above. Good repeatability was seen over the starts and the fast λ was similarly repeatable.

This data will be of importance to reduce emissions over this critical part of the drive cycle.