An Electronic Fuel Injection Enhancer (EFIE) is needed to correct O2 sensors signal to the ECU. The high Oxygen composition in the exhaust due to HHO injection in the combustion chamber will cause the O2 sensors to read a constant low (below 500mV). In turns, the ECU interprets it as LEAN fuel condition. It increases the firing of the fuel injectors, spitting more fuel than needed into the engine. Thus, the EFIE adjustment is critical to optimize fuel economy especially with Water or HHO-powered and fuel injection controlled vehicles.