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Make Your Own O2 Sensor Eliminators


Trace

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The whole deal with the O2 eliminators is it makes the ECU default to ONE setting which is system failure rich, thus the Power Commander can be programmed to correct this over rich state & will NEVER see a varying signal from the ECU when the ECU goes into closed loop mode.

The eliminator or resistor serves one purpose & that is to keep the ECU error light OFF, it does this by allowing the sensor heating circuit to flow power, the resistance of the resistor does not really matter, the ECU only monitors voltage, the 330ohm was used as it roughly matches the draw of the sensor heater coil, but really any resistor that will allow flow will work, just don't use to high a one as it will melt the ECU !

In fact you only need one eliminator to achieve this, doesn't matter which O2 sensor cable you attach it to the ECU just bases all 4 injectors one the one sensor it thinks should be working due to the heater being on, rather than the standard 2 cylinders per sensor. You can test this by just unplugging one O2 sensor, the ECU will not show a fault, but will when both are disconnected. The ECU does not receive a sensor signal, so defaults to a fixed rich map, which is why it does not show an error !

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@CandyRed: Yeah at the the end of the day a programmable box is the best answer.

Bypassing the 02 sensor substitutes one problem (too rich) for another (too lean or too variable) but it helps some I guess. Getting the map right would help more.

But I will say this, I got my 30 cents worth out of this mod, so kudo's to OP.

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Is this mod only for the vtec vfr,are the 98-99 bikes better because they don't have cats/02 sensors in the exhausts? you can tell I know very little on this subject,just read most of this thread and my head hurts

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This mod is only for any bike running a PowerCommander. If you don't have one all you will do is make your engine run very rich & see your fuel mileage get very poor !

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Is this mod only for the vtec vfr,are the 98-99 bikes better because they don't have cats/02 sensors in the exhausts? you can tell I know very little on this subject,just read most of this thread and my head hurts

The 98-99 VFRs without cats are among the best fueled stock bikes ever made.

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  • 2 months later...
  • 2 years later...
  • 2 years later...

Sorry for resurrecting an ancient thread. Is a 9W 330ohm resistor any different in this case? Thats the only thing I can find quickly locally. Obviously I know nothing about electronics. 

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I've recently installed a o2 sensor eliminator ant a slip on exhaust on my kawasaki zx6r ABS 2015, everything looked fine, engine check light was off as supposed to but when I cruise at low rpm's in 5th or 6th gear engine check light comes up. Does that mean that my o2 sensor eliminator is bad?

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  • 2 years later...
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And yet another resurrection of this thread...

 

I have a year 2000 vfr800. All this has made me wonder if a 1998/1999 ecu could be plugged into my bike, eliminating the circuitry and need for O2 sensor eliminators. Anybody?

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Why its just a simple resistor.  You probably could.  You have to compare the wiring diagrams and make sure all the pin outs and the connector to the ecu is identical.

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I would check the over/under on the cost of a new ECU and making it work to include using the catless 98/99 headers or VFRD headers, vs. just buying a Rapid Bike Racing and fixing and upgrading it all at the same time.  

 

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8 hours ago, VFR750F3 said:

Why its just a simple resistor.  You probably could.  You have to compare the wiring diagrams and make sure all the pin outs and the connector to the ecu is identical.

Because, after reading thru the entire thread, and watching all the videos, I'm still not sure if unplugging the o2 sensors causes it to run rich or (after three minutes) causes it to run a default map. Opinions vary and it's not clear.

 

Also, I just wondered if anyone has done it.

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4 hours ago, ShipFixer said:

I would check the over/under on the cost of a new ECU and making it work to include using the catless 98/99 headers or VFRD headers, vs. just buying a Rapid Bike Racing and fixing and upgrading it all at the same time.  

 

I'm on the list for the next batch of VFRD headers. I have a set of 98/99 headers that I could put on, but I probably won't bother with that. I'll just wait for the VFRD headers. A Rapid Bike is probably also in my future.

 

I'm not actually having a problem with the way my bike runs. My o2 sensors are plugged in and I don't notice any flat spots or surging. This bike runs pretty darn good.

 

I was more just curious if anyone had tried a 98/99 ecu on a 00/01 bike. I wondered if it worked, and if there were any hidden benefits/drawbacks.

 

Cheers!

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2 hours ago, Ziffer said:

Because, after reading thru the entire thread, and watching all the videos, I'm still not sure if unplugging the o2 sensors causes it to run rich or (after three minutes) causes it to run a default map. Opinions vary and it's not clear.

 

Also, I just wondered if anyone has done it.

Both. There's always a base map ECU uses to start with. Then modifies these pre-programmed values using other variables such as air-temperature, air-density (altitude), O2-sensor, etc. So underlying default map IS super rich. Then ECU uses O2-sensor feedback to dial back mixtures.

 

This helps easier starting when O2-sensor is cold and ignored, mixture is richer for easier starting. Then as engine and O2-sensor warms up, ECU leans out mixture for more optimal combustion and power. Remember that '60s hot-rod saying...

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also "Lean is mean!"

 

Max-power is made around 13.5:1 AFR on NA engines. Due to crudeness of carbs and uneven AFR curve, super-rich 10:1 mixtures were default from factory. Leaning out mixtures typically picked up +10-15% more power.

 

Even with modern EFI systems it's common to find 11:1 AFR WOT mixtures from factory. This is safety margin in event you encountre bad petrol out in boonies on super hot day. Or have clogged injectors or failing pump. No manufacturer would be crazy enough to design engine on ragged-edge that would self-destruct if users don't follow every single operating suggestion in manual.

 

In that regard, on any bike, O2-sensor is ignored (open-loop) when load is higher than 70-80% anyway since it's only accurate at 14.7:1. Then pre-programmed  11-12:1 AFR is used from underlying base map for safe mixtures. Give unplugging O2-sensor to test 1st to see how bike runs. Won't be any different under high loads because mixtures will be exactly same. The resistors are only prevent FI light on dash. Pretty simple to just do this and tape over.

 

gallery_4428_747_79599.jpg

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There is a way to see what your bike is like without the closed loop mode with the O2 sensors, discovered by that other forum.  Turn ignition key "ON" and then kill switch "ON."  Let pump prime (whining noise).  Turn ignition "OFF."

 

Turn ignition "ON" and hit starter before the whining noise and dash light/pattern ends.  For one reason or another, this puts the bike in a completely open loop mode without the O2 sensors, riding to a fixed map.  

 

Haven't ridden a 5th gen enough to know if it's noticeable, but a shitty thing about the 6th gen is there is clearly open loop logic on top of the closed loop control, where even with eliminators it will still dial back mixture in a noticeable way.  Whether the key/switch dance is an intentional bypass built in by Honda, or a flaw that faults out that logic, we don't know.  But it works.

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6 hours ago, ShipFixer said:

There is a way to see what your bike is like without the closed loop mode with the O2 sensors, discovered by that other forum.  Turn ignition key "ON" and then kill switch "ON."  Let pump prime (whining noise).  Turn ignition "OFF."

 

Turn ignition "ON" and hit starter before the whining noise and dash light/pattern ends.  For one reason or another, this puts the bike in a completely open loop mode without the O2 sensors, riding to a fixed map.  

 

Haven't ridden a 5th gen enough to know if it's noticeable, but a shitty thing about the 6th gen is there is clearly open loop logic on top of the closed loop control, where even with eliminators it will still dial back mixture in a noticeable way.  Whether the key/switch dance is an intentional bypass built in by Honda, or a flaw that faults out that logic, we don't know.  But it works.

Thanks for info!

Wait... if you remove O2-sensors on 6th-gen, it still pulls back mixtures?

How does it know engine's running too rich?

How does it know how much fuel to pull?

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6 hours ago, DannoXYZ said:

Thanks for info!

Wait... if you remove O2-sensors on 6th-gen, it still pulls back mixtures?

How does it know engine's running too rich?

How does it know how much fuel to pull?

Yep, it does.  Answer is...there's no other way to close that loop I can think of.  Till I learned about the key switch sequence I thought it was just the limitations of early ECUs and whatnot.  Like I have seen some examples where the steps in an older engine controller are "big" so things suddenly and noticeably change over a few hundred RPM.  That's sort of what the VFR always felt like to me when it was stepping the fuel up and down at cruise and I wrote it off as the limits of the day.  And some people notice it, and some people don't, so it was also probably down to the tolerances of each bike and whatever the sensitivity of that rider is.

 

Now what I think is the behavior between O2 sensors active or not is so arbitrarily close, it's probably really an open loop algorithm in implementation if not outright design, and Honda just tipped the scales overall towards emissions and efficiency.  We know the manufacturers have always done this with lean mixtures at cruise RPMs to meet mandates, this is just like Honda went the extra mile when they didn't have to and it's super annoying.  They might have even had O2 eliminators in mind, and wanted to do things to protect the longevity of the cat, etc.

 

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  • 6 months later...

Hey kentguy55. It's not clear if you are asking for pictures of the normal 02 sensor location, or where to check for or install O2 sensor eliminators.

 

If it's the latter, doesn't the first post in this thread answer your question - I m no expert but those photos look like a Gen 5 to my eyes.

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