In the past, fuel savers would not work when applied to fuel injection because those systems are actually designed to prevent efficient combustion. Adding an HHO kit to your engine’s air-intake increases the combustion efficiency. In order to get the most MPG gains from the HHO kit, the oxygen sensor’s voltage needs to be externally regulated. This is because the vehicle’s factory computer does not know how to deal with the addition of HHO / Brown’s gas in the air intake system.
Increasing the combustion efficiency of an engine increases the exhaust oxygen percentage. Most fuel injection engines use an oxygen sensor to infer the air/fuel ratio of the engine, the increased oxygen content in the exhaust is ‘read’ by the computer to be a lean mixture in the engine. The computer then adds extra fuel to bring the pollution back to ‘normal’.
This problem led to the development of the Electronic Fuel Injection Enhancer (EFIE, pronounced Ee-Fy). The EFIE allows you to apply an offset to the voltage coming from the oxygen sensor, so your vehicle’s computer is completely unaware that the oxygen content of the exhaust has increased.
Only the O2 sensors in front of the catalytic converter should need the EFIE device as the ones behind the catalytic converter are there to make sure the one’s in front are doing their job.
More about HHO: The H2 and O being pumped into the system will react with themselves and then the additional oxygen being pumped in will react with the gasoline. However, since the H2 and O combust more efficiently, it will also increase the efficiency of the gasoline being burned resulting in more oxygen exiting your cylinder and thus making your catalytic converter work less.
How EFIE’s work:
The oxygen sensor “tells” the computer what the oxygen content is by providing a voltage on it’s signal wire between 0 and 1 volt. 450 millivolts (.45 volts) means that the fuel/air mixture is correct. Higher values means the mix is rich (has too much gas), and lower voltages means the mix is lean. By adding voltage to the sensor’s output, we can compensate for the additional oxygen in the exhaust.
The Electronic Fuel Injection Enhancer (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 millivolts, the amount of this added voltage. This allows the computer to be unaware of the additional oxygen content of the exhaust from the HHO generator, and the electrolyzer can now achieve it’s full potential in fuel savings.
Most cars have oxygen sensors both before and after the catalytic converter. The ones downstream from the 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. EFIEs are only needed for all upstream oxygen sensors.
Where to Purchase
There are kits/instructions available from sites that will tell you how to make your own EFIE, but if you don’t have time or the skill to make one there are stores that sell already build EFIEs. If you have purchased an HHO kit or are considering it for a fuel injected vehicle, go to EFIE Devices, to get an already assembled EFIE device.








#1 by Raul Trevino on May 14th, 2008
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I sent you an email and it bounced back.
Raul
#2 by luciano on May 29th, 2008
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1992 toyota 22-RE EFI- CAn i make a HHO enhancer for my pickup?Oxygen sensor has 4 wires?i have a HHO generator already.
Thanks
#3 by Jermy Johnson on June 17th, 2008
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There might be a way to bypass the o2 generator or try getting an EFIE device from the link in the article.. Different cars have different sensors, but the folks that make the premade EFIEs should be able to help.
The sensors only work effectively when heated to approximately 800°C, so most newer lambda probes have heating elements encased in the ceramic to bring the ceramic tip up to temperature quickly when the exhaust is cold. The probe typically has four wires attached to it: two for the lambda output, and two for the heater power, although some automakers use a common ground for the sensor element and heaters, resulting in three wires. Earlier non-electrically-heated sensors had one or two wires.
#4 by Joe Shea on July 7th, 2008
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What happens if you forgo the EFIE kit and simply pull the fuses on the MAP oxygen sensors (in my Saturn, one in the exhaust manifold and the other aft of the catalytic converter)? Will that disable them and allow the HHO to to get mileage gains? Or do the reactant metals in the sensors run independently of the car’s computer?
#5 by rich carter on July 30th, 2008
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if you pull the fuses your ecu or computer will guess that the units are damaged and will add more fuel or make it run richer in order to keep you from running to lean and burning your valves.
#6 by Gary on August 18th, 2008
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To the person with the 1992 Toyota pickup. I have the same style p.u., you will find the 4 wires from your sensor are Brown, Black, Pink/with blue, and White/with red. The brown is the signal lead and runs between 1 and 9 Millivolts. Youll find the sensor just ahead of the catalytic converter on top of the exhaust pipe. I wrapped the inside part of the sensor with tinfoil to reduce the amount of oxygen it senced. When I installed my HHO generator and water vaporizer, and ran the system I found a voltage of 5 millivolts being produced, which is about perfect for your engine computer. The wires run inside a loom on the passenger side of the engine. You can do your testing at this location. Mine runs pretty nicely this way. Good luck to you, Gary
#7 by Mark on September 9th, 2008
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Does the 2004 CL500 need an EFIE with HHO generator?
#8 by lincoln sexton on September 17th, 2008
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i have a 1987 cadillac seville and i inatalled a kit for hho that i assembled and hooked it up without any enhancers and i tested it for making hydrogrn and it din not increase my mileage.so what would be the problem
#9 by lincoln sexton on September 17th, 2008
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i have a 1987 cadillac seville and i installed a kit for hho that i assembled and hooked it up without any enhancers and i tested it for making hydrogrn and it did not increase my mileage.so what would be the problem
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#10 by keith on November 20th, 2008
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hi i have a 1998 hyundia sonata auto 1997cc injection engine will i need a EFIE thank you
#11 by keith on November 24th, 2008
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are you selling a efie for £30 including pp thank you
#12 by dean on November 26th, 2008
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im interested in buying an efie but we dont know if it needs 2 efie’s or 1 as the vechile has two oxy sensors, my vechile is a 2.7 v6 dodge magnum 2005 so can you let me know and will you supply me with what i need as im going into fitting the systems in england, and can you give me a price for shipping heres my address in england so you can check for costings: dean bulman, 141 southcoates avenue, hull, humberside, england, hu9 3hf, thanks deans
#13 by Richrd Weaver on November 27th, 2008
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I have been reading that a 4 wire O2 sensor does not work with a regular EFIE. I have read that if you find the pulsating wire going to the O2 sensor this is the wire to hook the EFIE unit to. Then I read that nothing works on a 4 wire O2 sensor. What is the truth about the 4 wire O2 sensor? Should I buy an adjustable EFIE that will totally by-pass the O2 sensor? I see one advertised that does such. I the EFIE is turned off things operate as normal but when the EFIE is turned on I set the the ohms and it operates off of the EFIE and not the O2 sensor.
Can you please reply by this E-mail for me I would appreciate it. As of now I do not know what the hell to do, EFIE,no EFIE or what.
Thanks
Richard Weaver
#14 by Jim on December 4th, 2008
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To Richrd, about the 4 wire O2 sensor. I have the same problem you have. I have a 2001 Toyota Camry with a 2.2L engine. I read if you have a 4 wire sensor there is one type that will still work. We have a wide band sensor. If it is classed as a Air Fuel sensor there is no such device on the market that I know of that works. If it is still called a O2 sensor you might get lucky with the products around. I’m thinking we might only be able to buy the O2 extender to place the sensor 3/4 of a inch back away from the pipe. I don’t like the idea if you don’t use the HHO generator.I still don’t know what to do? Some one please help us out…
#15 by manny on December 25th, 2008
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Hi, yes I agree is a problem to by pass the
sensores, yet I may be able to help.
I designe a digital controler that as tested on
menny cars, and so far so good.very easy to conect (3 wires) one switch that is on for savings, off to by pass to revert to standard.
more info? email fueleconomiser@telkonsa.net
regards
manny
#16 by Bulldog on January 20th, 2009
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Every engine being different,is their a difference in the voltage on all o2 sensors
or due they all run 0 to 1 millvolts? and if
that is true you should just have to increaase
only to 0.80 millvolts to compensate for the
rich fuel mix so you will have your mpg increase useing your hho.Tell me if I’m wrong or right and why!
#17 by Mike Kehrli on January 22nd, 2009
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Hi guys,
I can shed some light on some of the questions brought up above:
1) 4-wire sensors: There are 2 types of 4 wire sensors. Narrow band sensors most often use 4 wires. Narrow band sensors are the type that work with an EFIE, and are the most common o2 sensor at this time. There are however a new type of sensor called a wide band sensor. Wide bands come in 4 and 5 wire types. An EFIE will work on a 5-wire wide band and will not work on a 4-wire wide band. This is probably what you heard. At fuelsaver-mpg.com we have an EFIE made specifically for wide band sensors that will work with either 4 or 5 wire wide band sensors.
2) Bypassing the sensors. Some folks have asked if you can pull the fuse or otherwise disable the sensors and then not need a sensor enhancer (such as an EFIE or MAP enhancer). This actually won’t work. The easiest way to disable an EFIE (for instance) is to just cut it’s signal wire. Other folks have put a fixed voltage on this wire that is intended to “satisfy” the computer. Neither works because the ECUs are programmed to expect certain responses from the sensor, and when they don’t see them, they will ignore them. However, when this happens they go into a safe mode, and this means running the fuel mix very rich. This will cause fuel mileage to get worse than when you started, even when adding HHO.
3) There are some different types of narrow band sensors, and they have slightly different characteristics. The ECU is programmed to respond correctly for the type of sensor installed. However, almost all narrow band sensors are of the same type, and operate in the 0-1 volt range in the same way.
However the reason you can’t just put a fixed voltage to the ECU and have it work is that the ECU is looking for transitions where the voltage goes up above and down below the .45 volt threshhold. .45 volts is theoretically the voltage for the correct air/fuel ratio. But because it will never be this exact amount, it is always changing above and below this voltage. If the ECU doesn’t see these transitions, it knows the sensor is no good, and ignores it. This is always bad in terms of gas mileage.
I hope some of these answers helped.
#18 by gregg on February 22nd, 2009
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i have 3 2quart generators that seem to put a lot of hho. my car a 4cyl 94grand amm with the map sensor ehancer is getting 28-30mpg, mostly in the 28 range around town. sensor is set on the 2nd quarter setting, without the map sensor on i get 23-23mpg. my problem is i know im making more hho than when i had 3 1quart system, i got same milage but when placing tube from generators into water and veiwing the hho output my 3 2quart unit puts out 3times the hho and thats a low estimate. will a efei help get more milage and does anyone know who makes one that will work on my 94. also my 02 sensor is right on the exhaust manifold coming from the head. oh yey my car is rated for 23 city 28 hwy. on the hwy i got 44.5mpg with cruise set at 65mph and that was with the 3 1quart units,so i havent got to try the new 3 2quart generators systen yet but at the rate of hho produced i should get awesome mpg anyone one that can help me i would be much apprieciated these 2quart systems ive made draw like 5-6amps and produce lots gas and the 1quart systems i used blew fuses would heat up lose water from evaporation etc where this new system ive made is not hot to the touch and makes a lot more gas.
#19 by Tommy on February 25th, 2009
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I have a 1997 H D Ford F250 - 460 gas engine -auto-trans - 2 wheel drive. Want to add HHO ket (by the way I used HHO in my race car back in the 1970’s. However, I lost on keeping up with antything to do with motors etc., over the years) - Is there any way to get set up information on a EFIE unit - how to adjust - what other eqyuipment is needed etc?
#20 by chris on February 27th, 2009
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ive just installed hho kit in my 98 nissan altima. seems to work fine but he exhaust is dumping unburnt fuel and i can smell it coming out. i tried installing the EFIE on the Map sensor but nothing happens. has anuone encountered this problem or knows what to do?
#21 by gregg on March 2nd, 2009
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dont know none has answered or helped me yet
#22 by gregg on March 7th, 2009
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im not sure this will work for you but through trial and error, (ive written to many my struggle with milage using map enhancer) it looks like you dont turn lean knob as much as you think because from what ive read if you do it too much it does somthing called open or close loop, i forget which one but when i turned knob as much as i could before starting to stutter i got less milage. i currently have just turned my knob back and have noticed more power and im at 77 miles so far and am not reached the full mark on my tank, which looks to mean im getting more milage. i’ll post again later to let know results
#23 by D.L on March 16th, 2009
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THIS EFIE THING …. IS IT FOR WHEN U REMOVE THE CAT AN IT REPLACES THE O2 SENSOR SO THE ENGINE LITE WON’T COME ON ? KINDA LIKE AN O2 SENSOR OVERRIDE TYPE DEAL ?
#24 by gregg on March 17th, 2009
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no, its for tricking the 02sensor, nothing to do with cat or removing it. and is conected to the 02.
#25 by HELP on April 15th, 2009
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I have a Saturn 2000 s car. I can not seem to get the o2 enhancer to do a thing. Reading some of these posts it looks like I’m s- out of luck. I’ve spliced into the green wire, is that correct?
#26 by Johney Deen on May 16th, 2009
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Is this been checked for diesel? engines with no sparks…
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