Very simple EFIE circuit help...Im a beginner

Discussion in 'General Electronics Chat' started by mrbriteside1465x2, Feb 20, 2009.

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  1. mrbriteside1465x2

    Thread Starter New Member

    Jan 23, 2009
    Hello, my name is Sean and I am having issues with the circuit I designed to regulate the amount of fuel my car is using. I will do my best to explain everything to you and anything you can tell me will be a great help.

    First off, I have a 1994 Jeep Wrangler S 6cyl.
    There is one oxygen sensor upstream (engine side) of the catalytic converter.
    The engine is fuel injected.
    The oxygen sensor has 4 wires. 2 white wires, 1 grey wire, and one black wire. I did testing on the black and grey wires to see which one was the signal wire, and surprisingly, the black one turned out to be it. I had assumed that the grey wire would be the signal, but when connecting the multimeter to it, i found that the grey wire was ground and the black was signal. I am attatching the device to the wires right next to the sensor.
    In conjuction with the efie, I am using a homemade HHO generator as a fuel source in addition to gas.

    Efie Wiring
    (sorry for the lack of correct termonology, I am new to all of this and dont know specifics)
    The O2 signal wire connects into the eife and into a single pole, ON-OFF-ON switch. One side of this switch goes directly to the ECU (to use the normal O2 sesor readings), and the other side of the switch goes through 2, 1.5 v AAA batteries. Then it goes to an ON-ON toggle switch. One side of the switch takes the now over 3 v charge to a potentiometer. A very small red LED is hooked up to the positive charge just before the potentiometer, and the negative side of the LED is attatched to a ground wire. After the Potentiometer, the charge goes back to the wire of the O2 sensor that takes it to the ECU. The other side of the toggle switch is the same exact thing. I did a toggle to have 2 different settings. Now the way the 4 grounds are connected, (2 potentiometers, 2 LEDs) , they all come together to one wire and this ground wire is connected to the same ground wire that the o2 sensor uses. The way the signal wires work (2 pot wires, 1 wire from the very first switch) They come together to 1 wire which connects back to the o2 sesor wire to take the charge back to the ECU.

    Efie Problems
    I think that the way I have my circuit wired is very wrong. When I install this system on my vehicle, I attatch a multimeter to the ground wire and to the signal wire going to the ECU to monitor the voltage. After the car is running warm, I read the settings and play around with it. When the original switch is flipped to the side that is supposed to use the orgininal o2 sensor readings, it does not do so at all, and the potentiometers still have an effect on the voltage. When the first switch is in the off position, there is still a voltage going to the computer, which is also still effected by the potentiometers. Also, i am having a very difficult time keeping the voltage of the output under .90, which is way to high to acutally use. Could all of these problems be due to the fact that i wired the ground wires all together before actually going to the o2 ground, and that i wired the signal wires together before goign to the ecu? I am very confused at this. I am very assured that there are no "stupid" mistakes like a touching wire or mismatched wire or anything like that. I just cannot figure out why it is not working for me.

    I apologize if you are having trouble picturing exactly what is going on, please email me back for clarification on anything. any information you have that could help would be extremely appreciated.
    Thanks A LOT,
  2. mrbriteside1465x2

    Thread Starter New Member

    Jan 23, 2009
    Here is a diagram of the problem I have been having...

    I wonder is the problem when the several ground wires are all connected together before actually being grounded? or when the several signal wires are all connected together before going to the ecu?

    Is there a better way to wire the LED's than the way I am currently doing it? They currently get brighter/dimmer as the potentiometers provide more or less resistance.

    Thanks for the help,
    • efie.jpg
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  3. beenthere

    Retired Moderator

    Apr 20, 2004
    That is a wiring diagram, and not a schematic. The switch that should attach the O2 sensor or the fudge voltage to the ECU is wrongly wired. It should be an ON-ON type. The ECU input should be to the switch common, and the sensor to one side and the fudge circuit to the other. That way the ECU always has an input.

    All grounds have to be common. If your batteries are to provide some potential to the ECU while in fudge mode, the battery negative terminal should also go to ground. That way, you have +3 volts to work with.

    Your LED's are not correct, but I have no idea of the circuit function, so I can't suggest something better. For all I can tell, they may be circuit elements. A schematic would help greatly.

    There are several threads on this topic in other sections. It is pretty much the consensus that any mileage increases come from fooling the ECU into running lean, rather than any boost from your hydrolysis setup. Take care you don't burn your valves fooling with this thing.
  4. SgtWookie


    Jul 17, 2007
    It's a good bet that your Jeep is using narrowband O2 sensors. They won't work outside of a very narrow air/fuel ratio band; stochiometric. Adding hydrogen/oxygen to the air/fuel mix will throw the sensor off.

    Your modifications to the emissions system is a very bad idea, along with being illegal in most (if not all) states. The invalid input from the O2 sensor will cause the ECU to run in "open loop" mode with a default fuel map; you'll burn more fuel and have higher emissions than normal.

    If you DO manage to "fool" the ECU into running on the lean side, you risk a lot more than just burned valves. Broken head gaskets, head bolts, pistons, ring grooves, overstressed bearings and more will be your constant (and expensive) companions.
  5. Audioguru


    Dec 20, 2007
    You will stink up the highway with excessive nitrogen oxide as your valves and pistons burn from running too lean. Your jeep's exhaust will have the smell and high pollution of a car from the 50's.
  6. mikeross

    New Member

    Oct 2, 2009
    So the oxygen sensor or the emission system should not be modified, right? I've been thinking about trying it but since you have said that it could lead to many problems. i would not want to risk it anymore.
    Last edited: Oct 12, 2009
  7. shortbus

    AAC Fanatic!

    Sep 30, 2009

    you have a heated oxygen sensor. the black and grey wires should be the feed wires from 12V to heat the sensor when the engine is cold, so the ECM goes into closed loop sooner. the two white wires are the actual sensor output signals.

    earlier EFI/ECM systems only used two wires. no heat on the O2 sensor.

    unless you know how the complete engine management system works, be prepared to factor in the cost of a new ECM when you figure your fuel savings payback ratio!
  8. Jaguarjoe

    Active Member

    Apr 7, 2010
  9. beenthere

    Retired Moderator

    Apr 20, 2004
    This thread got resurrected by an HHO believer. In keeping with out automotive policy:
    the topic is closed.
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