all modern vehicles, either fuel injected or carbureted,
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 proportion.
vehicles 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, 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
is actually an artificial relationship, but has
been found to be workable with the existing techniques
of burning fuel in your car's engine.
a big problem with this scenario since, as soon
as you start adding a workable fuel efficiency device
like a hydrogen booster, the oxygen content in the
exhaust will rise.
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
less fuel is being used to produce an equivalent
amount of horsepower, and
(2) less oxygen is being consumed to create carbon
monoxide in the exhaust.
bottom line is there is more oxygen in the exhaust
as the fuel burning efficiency is increased.
now that we have spent time and money to install
a fuel efficiency device or two 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 device.
Solution is simple
The signal coming from the 02 sensor needs to be
adjusted to compensate for the increased fuel efficiency
we need to fool the computer into thinking that
the engine is still burning gas inefficiently, by
making it think there is less oxygen in the exhaust
than there actually is.
amount of change to the signal is easily adjustable
to accommodate different amounts of efficiency increase
from different size hydrogen boosters.
should be noted that an oxygen sensor handling device
(EFIE) by itself, is not a fuel efficiency device.
The EFIE could be used to control the vehicle's
computer and make the engine burn a little leaner
and this would 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 an increase in gas mileage using other
fuel efficiency devices such as a hydrogen booster.
one wire to the O2 sensor, attach the green wire
to the O2 sensor and the white wire to the computer.
Connect the red and black wire to a switched power
source. Turn on power and
Set the output to .25 -.3 volts with a VOM connected
to the white and green wire.
are two adjustments on the EFIE
You only need to use the voltage adjuster not the
Locate the oxygen sensor signal wire
easy way to do this is to look it up in your Haynes,
Clymer or Chilton manual for your car. OR, if you
don't have one of these, there is a service at www.ahdol.com
where you can pay a nominal fee, and get your wiring
diagrams emailed to you.
have also recently found a resource at www.autozone.com
whereby you can get your wiring diagram on your
Locate your car, year, make and model.
* Select "Repair Info" at the left side
of the screen.
* Then select, "Vehicle Repair Guides"
* then > Chassis Electrical > Wiring Diagrams
information is not available for all cars and trucks.
Unfortunately, the sensor can have 2, 3 or 4 wires,
and you have to know which one is the signal wire.
If you have 4 wires they will be:
1. Heater 12 Volts +
2. Heater ground
3. Oxygen sensor signal +
4. Oxygen sensor signal ground
you have 2 or 3 wires, then you can have a common
ground, or no heater wires etc.
The simplest setup is a one wire O2 sensor, which
is the signal wire. The O2 sensor gets it's ground
from the exhaust pipe. But you would still use the
following procedure to narrow down which wire is
Disconnect the wire harness to the O2 sensor.
Turn on the ignition.
Probe for 2 wires that produce 12 volts between
This will be the heater circuit and ground.
The two wires left will be the sensor signal and
the wiring harness, then strip a little insulation
off each of these wires and measure them with the
When you have found the right
wire you should get voltage reading that is constantly
fluctuating between 0 and 1 volt (.35-.65 volts
If the readings are negative, reverse your probes.
Now the positive probe will be the signal wire you've
been looking for. Cut this wire at a convenient
location for connecting the EFIE.
call the sensor side of this cut wire the sensor
wire, and the other side of the cut, the computer
rarely an oxygen sensor wiring harness will have
more than 4 wires. In this case, the sensor is possibly
a "wide band" oxygen
EFIE is not designed to work with all wide band
sensors, although some wide band sensors have an
interpreter that gives out a narrow band signal
before routing to the computer.
Now that you have determined which is the sensor's
signal wire, you can make the connections close
to the computer. If you used a manual or wiring
diagram, you probably have already located the wire
at the computer's wiring harness. If you had to
figure out the wires at the sensor itself, then
try to find the same wire at the computer's wiring
harness. It should be the same colors, but test
it with an ohm meter to be sure or just make the
connection under the hood.
worth it to get the signal wire located up by the
computer. This makes cutting into and hooking up
the EFIE much easier, especially if you are mounting
the EFIE inside the cab.
(2) Locate 12 volt power and ground
need to ensure that you have switched power, not
power directly from the battery.
When power is shut off to the EFIE, or the power
switch is turned off, the original connection between
the oxygen sensor and the computer is re-established.
This will allow the EFIE to be turned off and on
with your hydrogen booster if so desired. Simply
connect the red wire to the VOC (not shown here).
connecting to your hydrogen booster is inconvenient,
just use any circuit that is accessory key switched.
electrical diagram can come in handy here, and if
you don't find another device to attach to, you
can usually find a spare circuit in the fuse box
(you may have to add a fuse).
One installer used the oxygen sensor's heater power
for his EFIE's power, and this is perfectly acceptable.
1. This EFIE is not waterproof. If you mount it
under the hood, you will have to take care to cover
it if you need to steam clean your engine. You may
want to mount the EFIE in the passenger compartment
where it will be protected.
2. If you live in a very cold climate, where temperatures
are expected to be below freezing for a significant
number of days per year, you will want to ensure
that the EFIE is mounted where it will be warmed,
either by the engine, or inside the passenger compartment
or move the jumpers J1 and J2 to the heating position.
Attach the wires
Connect the red to your power source.
Connect the black to ground.
Connect the green wire to the oxygen sensor.
Connect the white wire to the computer.
should solder them and use heat shrink tubing to
insulate the connections from other wires. If you
don't have heat shrink, you can use electrical tape.
Take care to not reverse the connections for the
red and black wires as the EFIE will burn out!!!
It will make smoke and will smell bad...(;;) If
this happens, the unit can be fully restored by
merely replacing the voltage regulator. Contact
us for a new regulator if this occurs.