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Three-way conversion catalysts systems which provide control of three emission components - hydrocarbons, carbon monoxide, and oxides of nitrogen - generally require the use of closed-loop feedback control of the air/fuel metering system to provide a near stoichiometric exhaust gas composition. As an alternate fuel such as ethyl-alcohol is added to gasoline, the stoichiometric air/fuel ratio is altered. Conventional air/fuel metering systems do not compensate for this change. This paper studies the ability of the Volvo closed-loop control fuel injection system, now in use on vehicles in the United States, to maintain the stoichiometric air/fuel mixture needed for optimum emission control and to compensate for the change in fuel stoichiometry encountered in gasoline/alternate fuel mixtures. The system was found to have the ability to completely compensate for gasoline/ethyl alcohol mixtures up to 30% ethyl alcohol with no loss in emission control.