a combined fuel engine for reduced emission pollution in which the engine is provided with a conventional fuel injection system for injecting a conventional fuel such as gasoline or diesel oil high in carbon into a combustion chamber proximate the cycle time of peak compression and with an auxiliary fuel injection system for injecting an auxiliary fuel such as methanol , ethanol or liquefied natural gas high in hydrogen into the combustion chamber with the charge of air proximate the cycle time of low compression with means for varying the proportion of fuels to achieve a lean combustible mixture .