Alternative fuel supplement added to intake air?
Injectors are controlled by the computer, based on O2 levels measured in the exhaust. If an alternative fuel–not enough to run the vehicle, but to merely enrich the incoming air–were added before the injectors, the computer should compensate and cut down on the amount of gasoline injected. Any convenient alternative fuel that can be mixed into the incoming air stream should work, from hydrogen to wood gas. It only needs to be held below the level needed to operate the engine so the computer meters in whatever gasoline is needed to take up the slack. This uses the existing system to overcome the problem of achieving a proper fuel/air mix and greatly simplifies using an alternative fuel.
Please, no beliefs. You can get two points for a belief, but a belief without a reason is pointless. If it can’t work, I want the reasons.
the additional fuel would be measured by the MAF (mass air flow) meter and the computer knows that that amount of air needs x amount of fuel. The fuel system would deliver the fuel and the engine would be running rich. The O2 sensor would notice there is a lack of O2 and it would cut back, but the computer would over ride because if the O2 sensor tells it to cut back too much, the computer assumes the O2 sensor is bad. The computer will turn on the check engine light and you’ll be running rich, ie wasting fuel.
The HHO scammers say they can fix that by breaking the O2 signal line and fooling the output, but, if you are not injecting your HHO, then the engine will be running too lean and you’ll burn a hole in a piston..
SO, no, you can’t add much of the magic stuff.
Within limits.
The range of additional fuel for which that computer system could compensate
would be limited. (Less at higher altitudes.)
The algorithm postulates air in that intake manifold.
Sorry "don’t know" the limits. Not my field.