HHO Generators and EFIEs – Things to Know

HHO generators have become very popular in recent years, due to rising gas prices, but were actually invented in the early 1900's and one can find a variety of them all over the internet. There are basically two types; dry cell and wet cell. But which one is better. Because of its physical design, a wet cell tends to draw more current and waste energy in the form of heat. The housing itself also creates a problem. In older vehicles, room was not a problem but, over the years, it has gotten very scarce. A dry cell eliminates this problem because the (electrode) plates are sandwiched together resembling a fuel cell and there is no housing in the conventional sense. The close proximity of the plates also makes it more efficient, draws less current, and doesn't generate much heat compared to a wet cell.

Another consideration, if you are planning to run hho, is an EFIE (electronic fuel injection enhancer). This device compensates for the added oxygen that will be in your mixture along with the hydrogen. In older vehicles, only the upstream sensors (before the catalytic converter) were used in a/f ratio calculations. Since around the year 2000, more car manufacturers are using the downstream sensors as well and not all are documented. Some are also using 4 and 5 wires and the whole thing is getting rather complicated.

The threshold point for the sensor's voltage output is .45 volts. Any voltages that are higher than .45 volts are considered to be rich, and any voltages that are less than .45 volts are considered to be lean. When the sensor produces .45 volts, that is considered to be the correct air/fuel mixture; 14.7 to 1, air to fuel (by weight). The trouble with narrow band sensors is that they can't tell the ECU how rich or how lean the mix is. They only tell the ECU "rich" or "lean". Therefore, in normal operation, they are constantly changing voltages. Almost all EFIE designs that are in use today work by adding a voltage to the output of the oxygen sensor. While this approach does work, and has been the only solution available for many years, it has 2 problems:

1. There is a definite limit to the amount of voltage you can add. If you add .5 volts to the .45 volt threshold, the sensor voltage would never dip below the .45 volt line. This is an illegal condition and the ECU will quickly stop using the oxygen sensor if it never sees the voltage transitioning from rich to lean. In actual fact many ECUs need to see voltages lower than .45 volts before it will consider that the mix is lean, and so often you can't set an EFIE higher than 250 millivolts or so without throwing engine error codes.

2. It takes a relatively large change in the voltage to make a small change in the air/fuel ratio. This wouldn't be a problem in itself, but coupled with the fact that we can only add a limited amount of voltage, this causes an end result of a small change in air/fuel ratio.

This applies to upstream sensors only. The voltages from downstream sensors don't seem to jump around as much and just float around in the .2 to .3 volt range. Wide band oxygen sensors, unlike narrow band sensors, are not only able to tell the computer if the air/fuel mix is rich or lean, but how rich or how lean it is. It is able to signal to the computer a wide range of air/fuel mix readings. This makes it much easier for the computer to make adjustments to the fuel trim to achieve its targeted air fuel ratio.

These sensors were not used in any vehicles prior to 1997. Starting in about 1999, nearly all Toyota models started using them. However, other than various Japanese and German makes, most automobile manufacturers have yet to adopt them. Because they are a superior sensor, it's only a matter of time before they are universally adopted by all manufacturers.
If this all sounds confusing to you, YOUR RIGHT…IT IS. But you're not alone.