Disconnect The 02 Sensors

Discussion in 'Dyna Models' started by dynagc, Jun 7, 2010.

  1. dynagc

    dynagc Member

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    I put the TFI fuel management system on my 09 Dyna and it came with jumpers to by pass the 02 Sensors. So I was wondering what would happen if a person was to disconnect and bypass the 02 Sensors on a stock engine with no other mods ?????? Would the engine run richer??? or leaner???

    Gene
     
  2. Hoople

    Hoople Account Removed

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    The answer to that question can get very complex. Don't look at a narrow band O2 sensor as being a resistance that changes when exposed to different concentrations of oxygen. O2 sensors are actually little generators that generate a Very low amount of current with an output voltage of approx 1 volt DC when heated up by the exhaust.

    Since the output is low in current, the signal has to go into a very high impedance amplifier (part of the ECM). If you unplug the input to this amplifier (disconnect the signal source which in this case is the o2 sensor) the amplifier can "latch up" and peg.
    Depending on the amplifier, it may latch Up or Latch down (peg up or peg down).
    Therefore there is no telling how the ECM will handle this signal when you unplug the sensor. One thing for sure, it's not going to make the bike run better.
     
  3. grappleman

    grappleman Member

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    i am looking into putting the tfi and breather on my 07 low rider and was wondering the same thing about the 02 sensors. i was under the impression from reading somewhere that most people were plugging and tying off the sensors when installing the fueler. oh yes and this is my first post. i have been reading and learning for a little while and really appreciate all the knowledge here. thanks in advance for any insight.

    joe
     
  4. ultrat

    ultrat Senior Member Contributor

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    Welcome grappleman..........
     
  5. grappleman

    grappleman Member

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    thank you looking forward to being a part of the forum
     
  6. Hoople

    Hoople Account Removed

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    Joe, If I understand you correctly, don't you mean UN-plugging and tying off the O2 sensors.
     
  7. Breeze3at

    Breeze3at Well-Known Member

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    Welcome Dynadc and Grappleman! I UNplugged the 02 sensors on my '07, and tied them out of sight. Some people remove them completely and plug the bungs. Evidently the TFI is configured to send it's own signal to the ECM for the 02 sensor function. Whatever Doebeck did, it's a simple to install and worthwhile addition to my bike.
     
  8. Hoople

    Hoople Account Removed

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    That's what I was thinking.. Thanks for clarifying that for me Breeze.
     
  9. grappleman

    grappleman Member

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    hey guys sorry it took me so long. had to actually work for awhile!! yes i was referring to either removing the sensors and plugging the holes or un plugging the sensors either way, wondering what the thoughts were from more knowlegeable people than myself.

    thanks for the insight so far.
     
  10. dynagc

    dynagc Member

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    Grappleman: I did unplug the 02 sensors and tied them back. I did not remove them and plug the holes. TFI comes with jumpers to plug into the wires going to the ECM from the 02 sensors. My bike is stock at this time and shows a distinct improvement with the TFI. It idles smoother and is quicker in all gears especially at low RPM's. I am very happy so far. I have the Screaming Eagle stage 1 air breather on order from Zanottis ( back ordered ). I will be doing the stage one exhaust plug knock out maybe tomorrow. Hope this info helps you or anyone else interested in this mod.

    Gene