Fuel Effects on Emissions from an Advanced Technology Vehicle, Part II 940783

A 1991 Toyota Camry equipped with an electrically-heated catalyst/light-off converter system was evaluated for emissions in duplicate over the light-duty Federal Test Procedure (FTP) with three different fuels. Evaluations were conducted with the electrically heated catalyst (EHC) in place, both without any external heating and with the EHC operated using a post-crank heating strategy The EHC system was placed immediately upstream of an original production catalyst which was located 40.6 cm from the exhaust manifold. The three test fuels were: 1) a fuel meeting California's Phase II gasoline specifications; 2) a low-sulfur (48 ppm) version of the Auto/Oil industry average gasoline; and 3) the Auto/Oil industry average gasoline, RF-A. On average, NMOG emissions and the ozone forming potential of the exhaust hydrocarbons exhibited the following trend for tests run in unheated and EHC-active modes: Phase II < low-sulfur RF-A < RF-A. EHC operation on this test vehicle resulted in approximately a 50-percent reduction in average NMOG emissions, relative to unheated operation, independent of fuel composition. NMOG mass emission rates when operating on either version of the industry average gasoline were near the 50,000-mile LEV standard, but exhibited a strong dependence on the temperature achieved by the EHC during the post-heat period. Mass emission rates of toxics including formaldehyde, acetaldehyde, 1,3-butadiene, and benzene are summarized both with and without the EHC active.