Neat site Java!
Stolen from Chevron's site:
Fuel Leaning Oxygenated gasoline leans the air-fuel mixture of carbureted engines and fuel injected engines which don't have an electronic control module (ECM) (see Chapter 5). Engines with ECMs become fuel lean when the ECM is not controlling - when the engine is cold or the vehicle is being accelerated rapidly. The rest of the time, the ECM adjusts the air-fuel ratio to compensate for the oxygen in the fuel. If a carburetor is set to provide a very fuel rich mixture, fuel leaning might improve performance. Otherwise, fuel leaning can degrade driveability; the extent depends on the engine's calibration.
This did make me wonder. On a vehicle like ours, if the fuel is going to make the car run lean, it is going to add
more fuel to compensate. The point of the oxygenated fuel is to produce fewer CO and HC. What is that going to help if the car
needs more fuel just to get around?
