Search Results

The effects of fuel sulfur level on tailpipe emissions from advanced technology vehicles were explored in Phase 1 of a study conducted under the Petroleum Environmental Research Forum. In this study, fuels having three different levels of sulfur were tested according to the Federal Test Procedure (FTP) in low-mileage production vehicles designed primarily to meet California's Transitional Low Emission Vehicle (TLEV) standards. The three fuels consisted of a base gasoline containing 25 ppm by mass of sulfur, with the other two fuels created by doping the base fuel to 300 ppm and 600 ppm sulfur, respectively. Nine TLEVs and one Federal Tier 1 vehicle were tested at least twice on each fuel in an order that was balanced in time and randomized among the vehicles.

As part of the Auto/Oil Air Quality Improvement Research Program (AQIRP), a fleet of 299 1983-1993 “real world” light duty vehicles and trucks were acquired from inspection and maintenance (I/M) lanes and tested at prevailing ambient temperatures for their hot soak emissions for the first hour after the engine was turned off. When found, high-emitters were repaired and retested to quantify the effectiveness of the repairs. Also, I/M pressure-purge tests were performed to determine whether such tests could properly identify high-emitting vehicles. Measured hot soak emissions ranged from less than 0.1g HC to as high as 49g HC. Twenty percent of the vehicles tested accounted for nearly 80 percent of the total hot soak emissions, with no single common hardware component identified as the primary cause.