This question is one of the most argued points when it comes to HHO generator kits on vehicles, so I thought it would be a good idea to go ahead and address the issue.
An EFIE stands for Electronic Fuel Injection Enhancer, and it was really invented back many years ago by a man named George Wiseman, who then shared it with the world to use as necessary to help cars with fuel injection work well with HHO boosters. The file was quickly shared all over the internet and became the standard for most EFIE's still in use today, though they have been vastly improved, and operate smarter (like in our advanced EFIE designs).
The tuner circuits were invented as a response to the advancement in car computer enhancement, and the advent of throttle body Injection (TBI), and Fuel Injection Rails to inject metered amounts of fuel into a cars engine. They solved a huge amount of problems that commonly occurred with carburetors, such as hard starting, vapor lock, stalling, rough idle, etc.
The fuel injector contains a small valve that opens and closes rapidly to allow a fast, fine mist of gasoline or diesel to be injected into the combustion chamber of the engine at the perfect time, in the perfect amount, based on the circumstances of the car engine (ie: the car may be idling, accelerating, decelerating, going uphill, towing a trailer, etc), and each circumstance requires a different response from the injectors to vary the fuel properly. The programming used to determine these conditions is put together in a series of "Fuel Maps", that have pre-designated timing sequences for the injectors.
The injectors are actually an incredible invention. Think of them as a miniature high pressure spray gun, that not only opens and closes in micro seconds, but with the computer programming, they are told to pulse faster or slower, and stay open faster or slower depending.
So what determines their pulse rate and timing? The computer programming. But how does the computer know what to tell the injectors? Only ONE way...through the engine sensors. The computer has No Other Way of knowing the condition of the engine. Without the sensors, it would be like a blind man trying to run a race in a country he had never been, having no idea what is around the next corner.
THAT is where the EFIE comes into play!
Stay tuned for Part Two where I will get into the sensors of the engine that control, and how the EFIE affects them, and why they are necessary for long term gains when using an HHO kit