Abstract
A fast response sensor for measuring carbon dioxide concentrations has been developed for laboratory use and tested on a spark ignition engine. The sensor utilises the well-known infra-red absorption technique with a miniaturised detection system and a high frequency sampling system resulting in a sensor time constant of approximately 4 milliseconds fast enough to observe CO2 concentration changes within a single event (intake or exhaust) of a normally operating engine. The sensor is simple to deploy and operates on a continuous basis. In this paper, the details of a sensor application are given: measurement of the concentration of burned gas that is vented back into the intake manifold at IVO under idle conditions.