Oxygen Sensor Adjustment - General Information
Almost all modern vehicles employ oxygen sensors to tell the vehicle's
computer if the air/fuel mixture is too rich or too lean. The computer
uses the information from the 02 sensor to determine if more or less
fuel should be added to the mix in order to maintain the correct
Gas vehicle engines (as opposed to diesel engines) are designed to
operate at an air/fuel ratio of 14.7 to 1. When these proportions are
being supplied to the engine, a certain amount of oxygen will be
detected in the exhaust by the 02 sensor, and this information is fed
into the vehicle's computer. If more oxygen is sensed by adding HHO
Gas with any Hydrogen on Demand system the computer thinks the mixture is too lean (not enough fuel), and
adds fuel to the mix. Likewise, if less oxygen is sensed, the computer
thinks the mixture is too rich (too much fuel) and cuts back on the
fuel fed to the engine.
There's a big problem with this scenario as soon as you start adding a workable fuel efficiency device such as an HHO generator. For any given air/fuel ratio, burned more efficiently, the oxygen
content in the exhaust will rise. If you have two or more efficiency
devices installed, even more oxygen will be present in the exhaust. The
oxygen content rises as the fuel is burned more efficiently for a
number of reasons. Chief amongst these are a) less fuel is being used
to produce an equivalent amount of horsepower, and b) less oxygen is
being consumed to create carbon monoxide in the exhaust. The bottom
line is there is more oxygen in the exhaust as the fuel burning
efficiency is increased by injecting hho gas.
So, now that we have spent time and money to install a hydrogen on
demand device, and we are getting a more efficient fuel burn,
what does the vehicle's computer do? It dumps gas into the mix in an
attempt to get an oxygen reading in the exhaust equal to it's earlier,
inefficient setup. This will then negate the fuel savings of just about
any efficiency device, and in some cases will actually cause an
increase in fuel consumption, despite having a workable fuel efficiency
The handling for this situation is simple. The signal coming from the
02 sensor needs to be adjusted to compensate for the increased fuel
efficiency being achieved by your Hydrogen on Demand system. Basically
the added oxygen in the exhaust fools the computer into thinking the
mixture is too lean, causing it to (incorrectly) richen the mix. We
need to un-fool the computer so it continues to give us the same amount
of gas as before. We do this by making it think there is less oxygen in
the exhaust than there actually is. The amount of change to the signal
has to be easily adjustable to accommodate the different types of
efficiency devices that are available.
The oxygen sensor produces voltages to communicate the oxygen content
to the computer. When the sensor reads below .45 volts, that means it's
lean, and when it reads above .45 volts, it's saying the mix is rich.
If you connect your volt meter to an oxygen sensor signal wire and
ground, while the engine is running, you'll see the voltage is
constantly changing, and you'll probably see voltages in the range of
.3 to .7 volts or so. In actual fact, the voltage is changing back and
forth from about .1 volt to about 1.0 volts, several times per second.
But a hand held meter is not quick enough to show this.
adds it's voltage to the sensor's voltage, which shifts the voltage
that the computer receives towards rich. This causes the computer to
provide less gas. Many people think we're trying to fool the computer
with an EFIE. That's actually not accurate. The extra oxygen in the
exhaust because of a more complete combustion is what's fooling the
computer. It's making the computer think the mix is too lean, and it's
compensating by adding gas that is not needed. The EFIE is un-fooling
computer. All we want to do is get it back to giving us a 14.7 to 1 air/fuel ratio again.
It should be noted that an oxygen sensor handling device, by itself,
is not a fuel efficiency device. It possibly could be used to control the vehicle's
computer, and make the engine burn a little leaner, and this could possibly give
a small increase in gas mileage. But this is not what it was designed to do.
It was designed to complement, and in some cases make possible, increased gas
mileage using Hydrogen on Demand
or other fuel efficiency devices.
If you need to purchase an EFIE for your project, you can find them here.
We specialize in accessories for fuel saving devices such as the EFIE and have
a number of different models to suit different applications and budgets.