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Electronic Fuel Injection Enhancer Basics

If you need to find out which EFIE is needed for your specific vehicle please use this form: ---> EFIE Information.


Most fuel injected vehicles will need an EFIE. To locate the correct EFIE go here, Which EFIE Do I Need?



Fuel injected cars and trucks use a computer, OBDI or OBDII, and sensor devices to sense and maintain the correct air/fuel ratio. The Oxygen Sensor is one of these key devises. Fuel injected cars and trucks have one or more of these oxygen sensors installed in the exhaust stream. The computer extrapolates what the air/fuel ratio is, based on the amount of oxygen in the exhaust, as reported by the oxygen sensors.

When a fuel saver device is installed, such as a hydrogen generator, the petroleum based fuel is burned more efficiently. One of the results of this is that there is more oxygen (and less unburned hydrocarbons) in the exhaust stream. This is a good thing, and is in fact, what we are trying to achieve. However, the computer will pick up on this condition as a "too lean" air/fuel mixture. In other words, what is now a desired condition in the exhaust system, will be interpreted as "not enough gas", and the computer will direct the fuel injectors to increase the amount of gas pumped to the engine.

The result of this is that the oxygen sensors and computer prevent an efficient combustion from occurring!

The Solution To This Problem Is An EFIE

The oxygen sensors "tell" the computer what the oxygen content is by providing a voltage on it's signal wire between 0 and 1 volt. 450 mill volts (.45 volts) means that the fuel/air mixture is correct. Higher values means the mixture is rich (has too much gas), and lower voltages mean that the mix is too lean. By adding voltage from the EFIE to the sensor's output, we can compensate for the additional oxygen in the exhaust system.

The EFIE does exactly this. It adds a floating voltage to the top of whatever the oxygen sensor is putting out. It has an adjustment that allows you to control, to within a few mill volts, the amount of this added voltage. This signal allows the computer to be unaware of the additional oxygen content of the exhaust, and the electrolyzer can now achieve it's full potential as a fuel saver.

Most cars and trucks have these oxygen sensors before and after the catalytic converter. The oxygen sensors downstream from the catalytic converter do not need to be treated. Their data is used to determine when the converter has gone bad, but are not used in the air/fuel calculations. The EFIE is only needed on all the upstream oxygen sensors.


You absolutely will not beat the quality of these efie's. You can find cheaper efie circuits, but when it comes to a quality product, you get what you pay for. I've used the Dual EFIE on my car for over two years and have never had a problem. These electronic fuel injection enhancers come with easy to follow instructions.

We sell this brand of EFIE's every day, and we have not had one single complaint ever. They usually ship within 24 hours if ordered Monday thru Friday, closed on the weekends. They come with easy install instructions. Made In America and 100% Guaranteed.


quad efieQuad Digital EFIE Basic

NEW! The Latest Breakthrough in EFIE Technology!

The Quad Digital EFIE Basic is the next new member of our family of digital EFIEs. Digital EFIEs allow much leaner settings on vehicles than other types of EFIE. We recommend Digital EFIEs for all narrow band oxygen sensors that are upstream of the catalytic converter. Note, that the Quad EFIE uses a pair of analog EFIEs for the downstream sensors (see the article in the link above to see why the downstream EFIEs need to be analog type). Digital EFIEs have the following benefits:

  1. Can make the air/fuel mix much leaner than earlier designs. With this device you can lug down your engine, and often kill it if you set it too lean.
  2. Absolutely rock steady adjustment no matter what temperature the environment. Will vary less than 1/2 of 1% over it's rated temperature range of -40 to 125 Centigrade.
  3. Will work with older, "tired" oxygen sensors that should have been replaced. Other EFIE styles may require these to be replaced. Mind you, if they are old, they should still be replaced. But if they are working prior to your EFIE install, they will still work with this EFIE.
  4. One adjustment pot modifies both upstream (Digital) EFIEs equally, and similarly, one pot adjusts both downstream (Analog) EFIEs. This makes these devices easier to set.


Which EFIE Do I Need?

Wide Band EFIE

We have produced the world's first EFIE that is designed specifically for use with wide band oxygen sensors. It will work with all types of wide band and AFR (Air/Fuel Ratio) sensors. To be clear, it is the EFIE of choice for both 4-wire and 5-wire oxygen sensors. Also note there is a variation of the 5-wire sensor that uses 6 wires. This device will work with these too. Please note, it will NOT work with narrow band sensors. For these, you must use any of our other EFIE product lines, such as the Dual EFIE Deluxe.

Note that this product is only available in a dual configuration at this time. This means that this device will control 2 wide band oxygen sensors. For vehicles with single wide band oxygen sensors, just don't hook up the other circuit.

This model comes in a mountable box, and encased in protective plastic. The wiring is 18 gauge, with quick disconnects that can unplug from the device for easy installation. It has one potentiometer that controls the air fuel ratio adjustment for both sensors. An LED shows when the unit is powered up. By using the included rubber cap to cover the potentiometer, the unit becomes waterproof.

These units have a start up delay of about 45 seconds. After approximately 25 seconds the unit will start ramping up. At 45 secs it will reach it's full adjustment to the sensor's signal. This delay is by design so that the fuel mix will be richer during engine start up.

This unit is highly precise. It's signal drift is less than 1% across it's entire operating temperature range, which is -40C to 125C (-40F to 257F). Note that the electronics can get that hot, but the casing will start getting soft at 90C (194F). "C" = degrees Celsius and "F" = degrees Fahrenheit.




EFIE Documents

Oxygen Sensor Adjustment - General Information

EFIE: Electronic Fuel Injection Enhancer, Described

EFIE Installation Instructions

Notes On Circuit Board & Basic EFIE Models

New EFIE Product Lineup

What Do I Need To Know About My Oxygen Sensor?

How to Read Your EFIE

How to Adjust the Range of the EFIE

Advanced EFIE Design