Efie. Electronic Fuel Injection Enhancer: It's purpose is to make it possible for other fuel efficiency devices to work. Basically an HHO fuel cell (HHO generator) adds HHO gas to the fuel mix which when burnt by the engine burns much cleaner than gas alone. The oxygen sensor data will cause ECU computer in your car actually uses MORE fuel in order to compensate for the extra oxygen Produced in your exhaust by your Hydrogen on Demand system so that wipes out the whole point of the fuel cell. The EFIE solves this by adjusting the signal to the computer so the computer is happy with the readings it's getting and makes the correct adjustments for the various conditions of the engine.
