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This paper describes the application of a non-dispersive infrared-based instrument designed to measure CO with a response time of 7ms. Spark ignition engine emission measurements recorded during the first 505 seconds of an FTP75 drive-cycle for a 4 cylinder engine are presented, including fast response hydrocarbon and NO measurements. An analysis of the engine-out (pre-catalyst) exhaust gas is provided. Data collected simultaneously with a standard emissions test stand and conventional dilution tunnel are compared to the high frequency measurements. Fast CO analysis provides new insight into cold-start fuelling calibration and cylinder-to-cylinder AFR variation. Under rich conditions, the strong dependence of CO production on the quantity of excess fuel allows a significantly faster estimate of engine stoichiometry than a UEGO sensor.

In a recent paper, a novel fast-response NDIR-based CO2 (fCO2) sensor was described, with applications to automotive engine gas analysis. Certain shortcomings were identified with the sensor. The present paper is concerned with the evolution of the sensor towards a mature instrument and an important application: the measurement of Exhaust Gas Recirculation (EGR) rates during rapid transients. The application described concerns transient EGR measurements at unprecedented bandwidths. Essentially, the technique is based on comparing the inlet manifold CO2 concentration with that in the exhaust. Sampling complications caused by the wide range of inlet pressures encountered in the inlet manifold are discussed. A comparison of EGR from the present test is made with those deduced by the engine controller and a standard slow bench instrument. EGR calibration errors are then identified and related to legislated emissions measured with a similar frequency response.