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This paper describes an investigation of the impact of various fuels, soak and test conditions on the emissions performance of a MY1996 Corsica TLEV on an IM240 test. The study also probes the impact of turning the engine off just prior to the IM240 test under these conditions. We found using a Wintertime federal fuel with a sulfur content of 485 ppm that the HC, CO and NOx emissions were increased when compared with similar tests at the same temperature of 16°C using the California Phase 2 fuel with a sulfur content of 32 ppm. When tests using the Wintertime fuel were performed at temperatures lower than 16°C, the emissions increased dramatically. In control tests, the engine ran at a constant idle for 15 min. prior to the IM240 with no engine turn-off. However, when the engine was turned-off just prior to the IM240, slight increases in tailpipe emissions resulted at 23°C and 16°C using California RFG.

The performance of the OBD-II catalyst monitor of a 2.2 Corsica TLEV was investigated while operating on fuels with differing sulfur levels. Testing was performed using a driving schedule producing operating conditions which were acceptable to the production OBD-II system for active diagnosis of catalyst performance. During each test, catalyst diagnostic data and emissions performance data were collected simultaneously. Tests were performed at 22° C using California Phase II (35 ppm sulfur content) and Indolene clear (470 ppm sulfur content) fuels, and at 4°C using a commercial oxygenated Winter fuel (320 ppm sulfur content). Four dynamometer-aged converters were using in the testing. Converter performance in the form of HC conversion efficiency was found to generally decrease when the sulfur content in the fuel was increased.

The following study was performed to investigate the in-use emissions performance of a California TLEV equipped with components aged in customer service on an enhanced I/M test. Fuels and ambient temperature conditions were chosen to compare I/M test conditions typical for California (moderate temperature on California Phase II gasoline) to those likely to be encountered in a Northeastern state (cold temperature on Winter grade fuel). To obtain repeatable results and simulate typical customer driving prior to the test, Bag II of the FTP schedule was used to simulate urban driving to an I/M lane, followed by a variable length idle to simulate waiting for the I/M test, followed by the IM240 test.