Flex-fuel variable displacement engine control system and method

[0013]FIG. 1 shows an example variable displacement engine (VDE) 10, in which four cylinders (e.g., two in each bank) may have cylinder valves held closed during one or more engine cycles. The cylinder valves may be deactivated via hydraulically actuated lifters coupled to valve pushrods, or via a cam profile switching mechanism in which a cam lobe with no lift is used for deactivated valves. Still other valve deactivation mechanisms may also be used, such as electrically actuated valves.

[0014]Engine 10 may operate on a plurality of substances, which may be delivered via fuel system 8. Fuel system 8 may include various tanks, alcohol separator units, control and / or mixing valves, and injectors as described in more detail herein. Specifically, the various substances in fuel system 8 may include multiple different fuel blends, injection locations, or various other alternatives. In one example, multiple different substances having different gasoline and / or alcohol and / or water conce