EFIE Installation Instructions

It would be a good idea to familiarize yourself with what an EFIE is by reading the following two documents:

Oxygen Sensor Adjustment - General Information

EFIE: Electronic Fuel Injection Enhancer, Described

If you are installing a Wide Band EFIE, then please go to: Wide Band EFIE Installation Instructions.

If you are installing a version other than a Deluxe Series EFIE then first see the document, Notes For Installing Circuit Board & Basic EFIE Models, and then return to these instructions.

0. Install your fuel efficiency device

The EFIE is not intended to be a fuel saver by itself. You should install a device that is designed to get more energy out of the same fuel, such as a hydrogen gas electrolyzer, a fuel vapor production unit, fuel heater, or other device that gets more power out of the same fuel by increasing the efficiency of the burn.

1. Locate the oxygen sensor signal wire

The easy way to do this is to look it up in your Haynes, Clymer or Chilton manual for your car. 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. I have also recently found a resource at www.autozone.com whereby you can get your wiring diagram, and specific service manual information on your sensors. However, the information is not available for all cars and trucks. To help you find your wiring diagram at autozone.com, follow the instructions found here. We also can often find your wiring diagrams in our automotive information service. Just fill out the Sensor Request Form, and in the comments section, request the wiring diagram. We don't ave them for all vehicles, and generally, they're not as easy to read and use as the ones from ahdol.com.

If none of these options are available, you'll need to locate the oxygen senor and then locate the signal wire by testing. 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:

Heater 12 Volts +

Heater ground

Oxygen sensor signal +

Oxygen sensor signal ground

If you have 2 or 3 wires, then you can have a common ground, or no heater wires etc. The simplest setup is a single wire, which is the signal wire and the sensor get's it's ground from the exhaust pipe. You can use the following procedure to narrow down which wire is which:

Disconnect the wire harness, turn on the ignition and probe for a wire produces 12 volts. This will be the heater circuit.

Next find the 2 wires that produce exactly 0 volts. These will be the heater ground and the signal ground. The remaining wire should be your signal wire.

Reconnect the wiring harness, then strip a little insulation from the signal wire and measure it to ground with the engine running. The voltage on this wire will vary from nearly 0 to about 1 volt. Since your meter will not be fast enough to see the lows and highs, it will average them out to about .2 to about .8 volts. The fluctuations will be so fast you have a hard time reading the numbers. Note, that you have to let the engine warm up a bit before you will get these voltages from the sensor.

Cut this wire at a convenient location for connecting the EFIE. We'll call the sensor side of this cut the sensor wire, and the other side of the cut, the computer wire.

Note: rarely an oxygen sensor wiring harness will have more than 4 wires. In this case, the sensor is possibly a "wide band" oxygen sensor. The EFIE has been reported to work with 5-wire wide band sensors.

Once you have determined which is the sensor's signal wire, you want to get it located up 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. Test it with an ohm meter to be sure. Sometimes they use the same colors for different things. Even if it's a pain now, it's worth it to get the signal wire located up by the computer. This makes cutting into it and hooking up the EFIE much easier.

Special Note: The most common reason for installation failures is an incorrectly located signal wire. You should test the wire that you have located and make sure you see the phenomena described above when the engine is running. If you don't see these voltages, then you must debug this step before proceeding. We have made a short video that will show you what your oxygen sensor signal will look like.

2. Locate 12 volt power and ground

You need to ensure that you have switched power, not power directly from the battery. You don't want the EFIE running 100% of the time. It's not that the unit couldn't run 100% of the time, it probably could. But it would slowly drain your battery.

Most of the fuel efficiency devices need switched power as well, and you can often piggy back onto them. Note that the EFIE draws negligible power. You can attach it to any circuit. The best choice for a voltage source is a fuel efficiency device, such as a Hydrogen generator. That way the EFIE only activates when the fuel efficiency device is turned on. Note that when power is shut off to the EFIE, or the EFIE's switch is turned off, the original connection between the oxygen sensor and the computer is re-established. If connecting to your fuel saver's power is inconvenient or inappropriate, just use any circuit that is accessory key switched. Your 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.

Ground can be the vehicle body, engine block or ground from another device, including the ground for the oxygen sensor itself. Just make sure that whatever you choose to use for ground has a negligible resistance (less than 10 ohms) when tested against the negative battery terminal of your car.

3. Mount the EFIE

You can use the mounting ears to screw down the EFIE to a suitable location on the vehicle body or firewall. Some people like to mount the device inside the passenger compartment of the car. There are some considerations about where you mount your EFIE that should also be reviewed:

The 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 or spray clean your engine. If this is something you regularly do, you may want to mount the EFIE in the passenger compartment where it will be protected.

If you live in a cold climate, where temperatures are expected to be below freezing 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. Below freezing temperatures cause the EFIE to come up to it's voltage offset very slowly unless it is physically warmed. This is because it doesn't generate much heat of it's own. In most cases this can be accomplished by mounting your EFIE in the upper rear of the engine compartment, close to the firewall, which will allow it to benefit from trapped engine heat. Newer EFIEs now come with jumpers that if set will cause the EFIE to generate more heat. These were intended for use in very cold climates. Find J1 and J2 on your circuit board. Set the following jumpers for increasing amounts of heat: J1, J2, J1 and J2.

4. Attach the wires

The EFIE multi-conductor wire has 6 colors: red, black, white, green, blue and brown. 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. For Dual EFIE units, the brown wire goes to the 2nd oxygen sensor, and the blue wire goes to the 2nd sensor's computer line. Hopefully you've been able to locate all these wires up by the computer in an easily accessible location. But if so, be sure not to cut them too close to the computer so that you have plenty of slack to work with them.

You 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. I personally always use heat shrink. It's more professional looking, and less likely to unravel later into a sticky mess.

5. Adjust the EFIE

You will now need to adjust your EFIE. They do not come from the factory with a particular starting voltage preset, so you'll have to set the initial voltage. I have found that .200 volts (200 millivolts) is a good starting point.