Build Your Own EFIE

Build your own EFIE.
When you use a fuel enhancer (Hydrogen Generator) on a vehicle to increase your miles per gallon, there will be extra oxygen in the exhaust stream. The 02 sensor sniffs this stream and when it sees this extra oxygen it sends a signal to the ECM/PCM. The ECM/PCM then interprets this signal for the amount to increase or decrease the engine fuel to bring the ratio back to 14.7 to 1. This actually defeats our purpose of replacing some fuel with our hydrogen mixture. It will actually decrease our miles per gallon average.
What we need is an EFIE (Electronic Fuel Injection Enhancer).
I found this schematic somewhere and saved it to my computer about a year ago. I have re-drawn it because the original was almost unreadable. I am posting it here for your use at your own risk. I have built one similar to these and it works as noted, but your mileage may vary as they say, due to values of some of the components you use. I will experiment with building one of these soon and let everyone know how to make them work.
The EFIE lets you to apply an offset voltage of a few millivolts to the 02 sensor wire coming from the 02 sensor going to the ECM/PCM. This will cause the ECM/PCM to believe the fuel mixture is too rich and leans it out. The ECM/PCM will be fooled into thinking it has made things right again. This should work for any fuel enhancement device you install.
You should make sure your engine is in good tune before applying any devices to enhance your mileage. This EFIE is a type that is set and forget it using the 20 turn pot that is adjustable with a small screwdriver. This will also keep everyone else from playing with the settings.
You will need a good VOM to check your settings with and to locate the correct wires from the 02 sensor. All resistors are 5% tolerance all electrolytic caps are 105 degree and the pot is a 20 turn 20k and should be hooked up so that you have a 0 reading between the center terminal and which ever one of the other 2 legs you use. You will not be able to buy the 105 degree caps at RS but you can find them online at many electronic sites. Digi-Key, Mouser, Jameco, Etc. You will also need a small perf board to mount all components on and solder 2×2 inch.
I will say it does not take much of an adjustment to make a big change on the pot so be careful in your setting it up.
This one had a switch to switch it into and out of the circuit, but I did not use it. I also did not use the Red and Green LED’s and R7 as they are optional and really not needed. You can check for operation with a VOM. The EFIE is connected by splicing into the wire leading from the 02 sensor to the ECM/PCM.

I connected my 12 volt source through a fuse, a relay, and to an ignition on circuit, which I would recommend. Definitely connect it to an ignition on circuit so that when the key is switched on the EFIE is on and vice-versa. You can purchase a relay at any auto-parts store. They usually come in a five terminal setup but could be 4 terminal. Two of the posts operate the relay. Not sure of the numbers without looking at one. Post 86 will be the one to your voltage source and 85 ground. The other posts 30, 87, (87a, hot with key off) are for your connections to your load. One is for another hot wire 30 and the remaining 87, is for your load. 87a is hot with the key off so don’t hook to that one. Only one will be hot when the key is on besides the voltage source. When the key is on it will pull in making the remaining post hot. This is what you want. So to check it you would plug a hot wire to the load terminals and find the one that doesn’t have power, and this should be where you connect your load. It will be hot with the key on.

Tip: Connect it to your voltage source for your HHO generator
which should be connected through a relay so that when the key is on everything is on.

Tip: If anything goes wrong at anytime later on, just clip the two wires spliced into the 02 sensor and connect the ends together and you are back to normal until you can get your problem fixed.

Tip: Use Bullet Connectors on your wires where spliced to make this easy to remove. Make sure you use one male and one female on each set of wires that can be connected together if the EFIE is removed for repair.

I also mounted mine in a box under the hood. Makes for a little difficulty in adjusting but when your are done you are DONE! Just be sure yours is waterproof.

Start with the R6 voltage offset in the lowest voltage setting. Start your engine and warm it up and drive. Adjust R6 for your best fuel economy over a few days of driving. Make tiny adjustments! This will allow the ECM/PCM to get used to the adjustments. When close you should be somewhere around 400 to 450 millivolts total. If you get a check engine light then you have applied to much voltage. Back it off and make TINY adjustments over DAYS of driving. Testing with your VOM while doing so will let you know where you are at and make a record of your adjustments so you can refer back to them before making a another adjustment or correction.
Here are 2 different versions of the schematic but I don’t know if they will work the same or not as I have not built them. Use at your own risk. If you have questions leave them in a comment and I will try to answer them.

EFIE Schematic 1

EFIE Schematic 2

There are some components that are variable and my require different values on yours depending on your transformer and these are C1, R4, R5.
efieB_parts_list.jpg with variable components The plans can use the G508 transformer. Just search that part number at DigiKey. They cost $6.80, plus shipping. Digi-Key G508 Transformer

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This post was written by Michael on October 27, 2008

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7 Comments so far

  1. admin June 16, 2010 10:39 pm

    Mine pulls about 12-15 amps when driving and puts out 1 liter per minute. We have gained about 10 miles per gallon.

  2. admin May 21, 2010 4:26 pm

    Your hydrogen booster must be capable of producing enough hydrogen gas in order for you to see any savings in miles per gallon.
    A very tiny amount of hydrogen will not do any good. 1 liter per minute will help with the miles per gallon. When this is used you can adjust for less petrol and notice fuel savings.

  3. cristian andres May 9, 2010 7:29 pm

    thanks, now I understand the engine has to work within their normal operating range will be damaged but I have another question that consumption of current (amperes) must have the optimum hydrogen generator in a sedan car to notice an increase in the MPG, thanks for your time …

  4. admin May 9, 2010 11:31 am

    You can do damage to your engine running it lean in hot weather. You will hear it start to ping or a slight knock.
    When this happens the piston rings will break if run in this condition.

  5. cristian andres May 8, 2010 10:22 pm

    thanks for the reply, I did a EFIE and test it in my car and it works, less powerful engine, but I just want to have an EFIE to prove, without a hydrogen generator, so I have that doubt and asked if you heard of some that use only the EFIE and if you had any problem with the engine at high temperatures in the combustion chamber or damage to motor fuel lean mixture?? thanks …

  6. admin May 5, 2010 3:39 pm

    I have been running one for almost two years and haven’t had a problem. But if the outside temperature is hot you need to use some caution on running a booster. Normally the computer will increase the fuel if the temp of the engine starts to increase.

  7. cristian andres May 2, 2010 1:57 pm

    hello, excuse my English using google translator, I have a question? have read that if a motor is gasoline drops too may suffer damages from the temperature in the cylinders and get to melt the headband of the piston, since the gas acts as a refrigerant in the cylinder, my question is whether the EFIE, you heard if any car has suffered damage by the decrease of the fuel injection? because I want to build an EFIE, thank you very much.

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