Regulated and unregulated exhaust emissions from in-use catalyst cars at normal and at low ambient temperatures

This paper presents and discusses test results obtained from a fleet of 44 current-technology passenger cars typical of European vehicles and employs three-way catalyst system with closed-loop air-fuel ratio control.
The tested vehicles represented 15 different types and had been in normal use for one to four years and their odometer readings ranged from about 10 000 to over 80 000 km. Tests were performed at normal (+22°C) as well as at low (-7°C) ambient temperatures using the US FTP75 test procedure. Normal CVS-system was used for exhaust sampling and analysis, but a continuous sampling with second-by-second analysis has also been performed in some tests. In addition to the regulated emissions (CO, HC and NOx), some nonregulated compounds have also been measured using the latest high-speed on-line FTIR analysis equipment.
Test results and discussion outlines the response of individual vehicles and their emission control equipment to low ambient temperatures. Unit emissions (g/km) are presented for the regulated and cumulative (in g[test] values for some nonregulated compounds (N20 and NH3).