A method for a multi-fuel vehicle includes: determining a first target amount of fuel to be injected for a combustion event of a combustion chamber of an engine; determining first and second fractions for the combustion event based on at least one of engine speed, engine load, and engine temperature; determining a second target amount of liquid fuel for the combustion event based on the first target amount and the first fraction; determining a third target amount of gaseous fuel for the combustion event based on the first target amount and the second fraction; selectively injecting a liquid fuel directly into the combustion chamber for the combustion event based on the second target amount and using a first fuel injector; and selectively injecting a gaseous fuel into a port of the combustion chamber for the combustion event based on the third target amount and using a second fuel injector.