When an mpg. improving device such as an electrolyzer is fitted to a vehicle, the result does not always produce better mpg. figures. Older vehicles which are fitted with a carburettor will see an immediate improvement. This is not the case for more recent vehicles which come with computer control of the fuel sent to the engine. When an electrolyzer is attached to the engine, it causes the fuel burn inside the cylinders to be greatly improved, with a corresponding improvement in engine performance. Unfortunately, the fuel computer is expecting the same amount of unburnt oxygen to come out of the engine, and when it doesn’t detect it, the computer increases the fuel flow rate in an attempt to get back to it’s normal, inefficient method of running.
That action cancels the mpg improvement produced by the electrolyzer unless something is done to adjust the operation of the computer.   For more information please go to the Patrick Kelly site: A PRACTICAL GUIDE TO FREE ENERGY DEVICES