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The purpose of our study was to investigate the effects of TAME and heavier ethers on reformulated gasoline. The research work focused on the comparison of Californian Phase 2 gasoline (CARB), current Finnish reformulated gasoline containing MTBE (RFG1), or MTBE+TAME+heavier ethers (RFG2) with non-oxygenated Eurograde gasoline (EN228). Significant reductions in exhaust emissions were achieved with all reformulated fuels when compared to the Eurograde fuel. For instance, benzene emissions were reduced as much as 40 to 50 % for all cars at two temperatures and the emissions of total toxics were reduced by 14 to 45 % depending on vehicle type and temperature. The lowest 1,3-butadiene emissions were achieved with CARB gasoline. The amount of PAH compounds in the particulate matter from the non-catalyst vehicle was lower with the reformulated fuels than with the Eurograde fuel.

This paper presents the results of a gasoline reformulation project carried out in Finland during 1993. The project focused on the impact of gasoline sulfur and benzene content on exhaust emissions. Twelve 1990 - 1993 model vehicles were tested using two fuel sulfur levels, 500 and 100 ppm, and two benzene levels, 1 wt.% and 3 wt.%. Another subject of investigation was evaporative emissins during refuelling. When the sulfur content of the fuel was reduced from 500 to 100 ppm, the regulated exhaust emissions from catalyst cars decreased at test temperatures 22°C as follows: carbon monoxide CO 14%, total hydrocarbons THC 7% and nitrogen oxides NOx 9%. At test temperatures -7°C the reduction of sulfur content gave smaller benefits expressed in percentages, but the absolute changes (g/km) were at the same level as at +22°C.

This paper presents the results of a gasoline reformulation project carried out in Finland during 1991. The target was to evaluate MTBE and ETBE as gasoline components with respect to operability and exhaust emission performance. The oxygenated fuels contained 2 to 2.7 per cent oxygen by weight. The oxygenated fuels reduced exhaust emissions significantly at normal ambient temperature. For non-catalyst cars the reduction of CO was 15 to 30 % and the reduction of HC was approx. 5 %. For three way catalyst (TWC) cars the CO emission decrease varied from 0 to 10 % and HC approx. 10 %. The use of oxygenates reduced exhaust emissions also at low ambient temperature, but not as much as at normal temperature. Cold starting was quicker and cold driveability was better when oxygenated fuels were used.

Intake valve sticking, created by the accumulation of deposits on the valve stems, caused cold starting problems and engine failures at low temperatures (below + 5°C). Sticking was promoted by the high olefin content in gasoline (over 25% FIA). Sticking did not occur if gasoline contained no detergent additives. Some additives even led to sticking while some solved the problem. Engine oils containing polymeric additives promoted sticking. Clearances of intake valve stems and stem seals were probably factors affecting sticking. Tests were made using cars on the road on an urban driving cycle.