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Make Your Own O2 Sensor Eliminators


Trace

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Given the propensity for rich-running engines to foul plugs, is that a potential downside of this mod? I did it to my 2004 and while the flat spot is gone, I can smell (and on cold days SEE) that my exhaust is "rich" smelling.

While I was no fan of the flat spot, I'd hate to trade fouled plugs for it. Thoughts?

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Guest Capflamme
Given the propensity for rich-running engines to foul plugs, is that a potential downside of this mod? I did it to my 2004 and while the flat spot is gone, I can smell (and on cold days SEE) that my exhaust is "rich" smelling.

While I was no fan of the flat spot, I'd hate to trade fouled plugs for it. Thoughts?

My bet would be, that without the o2 sensor the ECU will use a standard map based on injector opening time for each rpm/throttle opening combination that shouldn't make your engine run extraordinary rich (or lean). My idea of the thing is that the o2 sensor is just here to "fine tune" the AFR on certain conditions.

The question that I would like to raise is: Will the ECU interpret the signal from the resistance as it was from the o2 sensor? Will it try to correct for the eroneous data that it "thinks" it read from the o2 sensor? Because, if that is correct, the ECU will constantly try to make the AFR richer or leaner (depending on what signal the resistors send to the ECU).

That's why I'm asking about which wires are connected by the resistors, so I can better understand what this resistor actually do. Anyone can clarify this?

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Guest Capflamme
Given the propensity for rich-running engines to foul plugs, is that a potential downside of this mod? I did it to my 2004 and while the flat spot is gone, I can smell (and on cold days SEE) that my exhaust is "rich" smelling.

While I was no fan of the flat spot, I'd hate to trade fouled plugs for it. Thoughts?

My bet would be, that without the o2 sensor the ECU will use a standard map based on injector opening time for each rpm/throttle opening combination that shouldn't make your engine run extraordinary rich (or lean). My idea of the thing is that the o2 sensor is just here to "fine tune" the AFR on certain conditions.

The question that I would like to raise is: Will the ECU interpret the signal from the resistance as it was from the o2 sensor? Will it try to correct for the eroneous data that it "thinks" it read from the o2 sensor? Because, if that is correct, the ECU will constantly try to make the AFR richer or leaner (depending on what signal the resistors send to the ECU).

That's why I'm asking about which wires are connected by the resistors, so I can better understand what this resistor actually do. Anyone can clarify this?

Okay! I clarified this by myself <_< So in case somebody is interested, the resistor is connected between the wires of the heater of the lambda sensor (white ones on the lamba side of the connector). In fact the resistance of the heater circuit of the sensor is something like 10 ohm. So, you don't need a 330 ohm resistor specificaly, basically, any resistance that permitt some current to flow through the wires of the heater will do the trick. Personaly I used a 1k ohm reistor because it's the only one that I had, and the ECU was happy with it. So in fact, the ECU just check for some current flowing through the heater circuit for the diagnosis, if you just disconnect the signal and ground wires of the sensor, the ECU will not detect it, at least on a 06 fireblade. But, I wouln't just make a short circuit between the heater wires, You better put a resistor at least equal to the resistance of the heater circuit of your stock O2 sensor.

Edited by Capflamme
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  • 1 month later...
Guest 03VFR0078

For what it's worth, I did the resister mod this weekend on an otherwise stock (no PCM, no Pair/Flapper Valve mods, etc.) '03 VFR. It completely cured the flat spot that seemed to occur at constant throttle between 4k and 5k. Now I can loaf along at 4500 rpm, roll on the throttle, and the power comes on nice and smooth... all the way up until the Warp Drive engages at 7k, that is. tongue.gif Given how annoying the previous behavior was, I recommend this mod to everyone, regardless of whether or not they plan any further fuel-program mods.

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  • 4 months later...
Guest samfinland

Hello!

I installed PC III usb and didn ´t have any problems with FI light, untill i installed O2 eliminators... then FI light didnt go off no matter what.. so i unplugged O2 sensors and the bike runs fine with pc III only...

No need to do any O2 eliminator tricks ? :biggrin:

Well i got cbr1000 o2 eliminators LOL... no wonder they didnt work.

Now installed new ones and VifFeRi feels much better.

Edited by samfinland
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  • Member Contributer
Hello!

I installed PC III usb and didn ´t hawe any problems with FI light untill i installed O2 eliminators... then FI light was on and didnt go off no matter what.. so i unplugged O2 sensors and the bike runs fine with pc III only...

No need to do ani O2 elimibator tricks ? :biggrin:

-???

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Hello!

I installed PC III usb and didn ´t hawe any problems with FI light untill i installed O2 eliminators... then FI light was on and didnt go off no matter what.. so i unplugged O2 sensors and the bike runs fine with pc III only...

No need to do ani O2 elimibator tricks ? :biggrin:

Here's my understanding.

Both the PC III and O2 sensor help with air fuel mixture. With the PC III you can set your own air fuel mixture ratio. The O2 sensor determine if the air fuel ratio exiting a gas-combustion engine is rich (with unburnt fuel vapor) or lean (with excess oxygen). Information on oxygen concentration is sent to the engine management computer or ECU, which adjusts the mixture to give the engine the best possible fuel economy and lowest possible exhaust emissions. (information taken from Wikipedia)

If you leave the O2 sensor in tact (no eliminator), what ever you set in the PC III will be over ridden by the O2 sensor. There by acting as if you didn't have a PC III. Someone with much more knowledge and better understand can provide a better response or correction to my post.

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Guest samfinland

^Ty for you reply Michaelf3..

That seems to be right(looked different recources)

So maybe i go and try those resistors back... and tur acc pump feature on allso.

P.S lovely +4 to +8 Celsius here...

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  • 3 months later...
Guest Garrett

Hello to all, I'm new here but have a question reguarding the resitors ( 330ohm/1/2 watt ). How hot are they suppose to get the ones I installed got hot to the touch but not enough to burn and also what size are the bolts that close off the Sensor holes, 18mm is too small.

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Hello to all, I'm new here but have a question reguarding the resitors ( 330ohm/1/2 watt ). How hot are they suppose to get the ones I installed got hot to the touch but not enough to burn and also what size are the bolts that close off the Sensor holes, 18mm is too small.

I have block off caps at work. They come on all new converters. I can get the exact size for you.

Or do you mean what size hex is on the o2 sensor?

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Hello to all, I'm new here but have a question reguarding the resitors ( 330ohm/1/2 watt ). How hot are they suppose to get the ones I installed got hot to the touch but not enough to burn and also what size are the bolts that close off the Sensor holes, 18mm is too small.

It's my understanding that the resistors are there to simulate the presence of the heater element in the o2 sensor (the two white wires on the sensor connector), so I suppose that's why they get warm. The other two pins are left unconnected, and present a reading of 0 volts (full lean) to the ecu, causing the ecu to attempt to compensate by going full rich. The power commander then makes the final adjustment to the injectors. Obligatory caveat: I'm not an EE. I just google alot.

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Guest Garrett
Hello to all, I'm new here but have a question reguarding the resitors ( 330ohm/1/2 watt ). How hot are they suppose to get the ones I installed got hot to the touch but not enough to burn and also what size are the bolts that close off the Sensor holes, 18mm is too small.

I have block off caps at work. They come on all new converters. I can get the exact size for you.

Or do you mean what size hex is on the o2 sensor?

The actual bolt size, NAPA # 704-1037 is too small for the closest sensor hole. I didn't try the other hole, I figured it would be the same size and NAPA said that 18mm is as large as they go, so far as drain plug size. I guess I could get a cut off wheel for the grinder and whack em off on both ends but I kinda hate to do that.

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Guest Garrett
Hello to all, I'm new here but have a question reguarding the resitors ( 330ohm/1/2 watt ). How hot are they suppose to get the ones I installed got hot to the touch but not enough to burn and also what size are the bolts that close off the Sensor holes, 18mm is too small.

It's my understanding that the resistors are there to simulate the presence of the heater element in the o2 sensor (the two white wires on the sensor connector), so I suppose that's why they get warm. The other two pins are left unconnected, and present a reading of 0 volts (full lean) to the ecu, causing the ecu to attempt to compensate by going full rich. The power commander then makes the final adjustment to the injectors. Obligatory caveat: I'm not an EE. I just google alot.

Yeah, I knew they would get warm, just did'nt know how warm . dose anyone know the benifits of removing the evap. cannister or is there any. A mounting tab got broke and wondering if I shold just remove the cannister or fix the tab.

Edited by Garrett
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Hello to all, I'm new here but have a question reguarding the resitors ( 330ohm/1/2 watt ). How hot are they suppose to get the ones I installed got hot to the touch but not enough to burn and also what size are the bolts that close off the Sensor holes, 18mm is too small.

It's my understanding that the resistors are there to simulate the presence of the heater element in the o2 sensor (the two white wires on the sensor connector), so I suppose that's why they get warm. The other two pins are left unconnected, and present a reading of 0 volts (full lean) to the ecu, causing the ecu to attempt to compensate by going full rich. The power commander then makes the final adjustment to the injectors. Obligatory caveat: I'm not an EE. I just google alot.

This is not at ALL what I understood the resistors to do. The resistor is providing a voltage signal that tells the computer the O2 reading is perfect. This takes the variability out of the air/fuel ratio. The heater circuit is not touched, it is just there to get the O2 sensor up to speed faster anyway.

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Guest Garrett

I was under the assumption that the resistors were to mearly keep the FI light from coming on. Removing the sensors was to keep them from sending the ECU a lean or rich enviroment in the exhaust gasses ( only within a certain throttle possition do the sensors send info back to the ECU ) and whithout the presence of a PC or other ignition/AFR programers, there is no need to remove the 02 sensors.

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This is not at ALL what I understood the resistors to do. The resistor is providing a voltage signal that tells the computer the O2 reading is perfect. This takes the variability out of the air/fuel ratio. The heater circuit is not touched, it is just there to get the O2 sensor up to speed faster anyway.

I'm pretty sure you have it backwards. The resistor is across the heater circuit to fool the ecu into thinking the o2 plug is still present, in order to prevent the FI light from going on. The other two wires are the voltage measurement circuit. These wires are not plugged in to anything, so I'm guessing the ecu will measure a steady 0 volts. At least this is what I gleaned by looking at the wiring diagram in the shop manual.

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This is not at ALL what I understood the resistors to do. The resistor is providing a voltage signal that tells the computer the O2 reading is perfect. This takes the variability out of the air/fuel ratio. The heater circuit is not touched, it is just there to get the O2 sensor up to speed faster anyway.

I'm pretty sure you have it backwards. The resistor is across the heater circuit to fool the ecu into thinking the o2 plug is still present, in order to prevent the FI light from going on. The other two wires are the voltage measurement circuit. These wires are not plugged in to anything, so I'm guessing the ecu will measure a steady 0 volts. At least this is what I gleaned by looking at the wiring diagram in the shop manual.

You are right, as I read through the thread better. I thought the mod made the bike think it was in the right range, instead it keeps it in closed loop mode. The resistors will get warm if you don't use a 1/2 watt resistor or so.

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Guest Garrett

I have the 330ohm / 1/2 watt and they get warm.

I bought the Scorpion exhaust for my 02 and man have I had a time with em. the right slip-on was the same size as the pipe it was to slip over, so I had to send them back. and have been waiting for an answer on what's to be done about it.. Another hurry up and wait ordeal..

Edited by Garrett
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  • 2 years later...
Guest Gamecock94

I just purchased a PC III off a member here without the 02 sensors. Is this Radio Shack Resistor method still the prefered route to go? Also, my bike (2003) has stock cans and K&N filter...is Cozye's maps still prefered as well?

Thanks!

Edited by Gamecock94
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  • Member Contributer

I just purchased a PC III off a member here without the 02 sensors. Is this Radio Shack Resistor method still the prefered route to go? Also, my bike (2003) has stock cans and K&N filter...is Cozye's maps still prefered as well?

Thanks!

I would say yes to the resistors and Cozye's map. I've been pretty much running this exact setup for about two years now on my '04 and it's been running like a charm fing02.gif

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Guest Gamecock94

I just purchased a PC III off a member here without the 02 sensors. Is this Radio Shack Resistor method still the prefered route to go? Also, my bike (2003) has stock cans and K&N filter...is Cozye's maps still prefered as well?

Thanks!

I would say yes to the resistors and Cozye's map. I've been pretty much running this exact setup for about two years now on my '04 and it's been running like a charm fing02.gif

Thanks! I'll pick up the resistors this week and hopefully get the PC III before this weekend. My brother and I are moving some stuff into my parent's new condo in Destin, FL and packing the bikes to ride back. Would be the perfect test riding back.

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  • 3 months later...
  • Member Contributer

OK, I was doing some research on this and totally barfed it up.

So if the consensus on O2 eliminators is that they're just fooling the ECU into thinking the sensor is there (heater wire), doesn't that mean that the ECU will go to maximum enrichment trim and peg itself there? What about a device which sends back a constant 0.5 volt signal back to the ECU so it's always thinking the reading is 14.7 AFR (Stoichiometric)? Maybe the Honda ECU is so stupid it actually won't trim the fuel in closed loop mode if the reading is 0 volts (open circuit)?

I see that Powercommander is now selling O2 sensor optimizers. These are an in-line device that goes between the stock O2 sensor and the ECU. The install guide for a Ducati 848 from Dynojet says that if you have a PCV you are not to put any values in any colums between 0-15% throttle or 0-5,250rpm, and no AFR values are allowed in Autotune tables in that area either! This must be because those bikes run Wideband O2 sensors which can't be easily disabled and need to have their signals intercepted rather than shut off. All the Dynojet documentation also says that "the O2 optimizer is trying to hit 13.6 AFR". That's not something you can do with a narrowband O2 sensor - they're either 14:1 (rich) or 15:1 (lean) and have no accuracy. Only a wideband O2 sensor can be used to set an AFR like "13.6" or something. Update: See my later post about how you could hit 13.6 AFR with a narrowband O2 sensor.

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Are stock VFR wideband or Narrow?

Im totally stock, ive not messed with them at all.

Sounds like the new optomisers are there in order to use the 02 sensor inputs?

It would seem to me, for an auto tune to work, the o2 sensors have to also be working

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Are stock VFR wideband or Narrow?

Im totally stock, ive not messed with them at all.

Sounds like the new optomisers are there in order to use the 02 sensor inputs?

It would seem to me, for an auto tune to work, the o2 sensors have to also be working

Stock VFR O2 sensors are narrowband and are disabled using O2 eliminators, forcing a permanent 0.0 voltage reading which would be seen by the ECU as a lean condition.

Autotune uses its own wideband O2 sensor which comes with it. The bikes with O2 optimisers can *also* use an Autotune, but must be disabled in the throttle/engine positions where the bikes' own ECU would trim the fuel mixture.

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I just did some workbench tests and I can categorically confirm that the Powercommander O2 sensor eliminators are indeed connected to the heater wire pins ONLY.

Also, I confirmed that you would need a 1/2 watt resistor or better to stop it burning out. This is because the power supply to the heater is 12 volts, and at 330 ohms that equals 0.4 watts of power dissipated. I imagine that Dynojet experimented with higher resistances but possibly found that at higher than 330 ohms the ECU deciced that the heater element in the O2 sensor is faulty. So, 330 ohm 1/2 watt or 1 watt resistor sounds like the best option. Of course this depends on whether the signal is a true regulated 12 volts or if it's whatever the bike's R/R is putting out, which could be up to 14.8 volts. That equates to about 0.6 watts of dissipated power, so a 1/2 watt resistor would be getting pushed at that point.

I also did some more research on the fuel mixture behaviour, and my best analysis so far is that connecting the O2 eliminators will force the ECU to go to a default rich condition when in closed loop mode. This is based on two sources/causes:

  1. An open circuit on the O2 sensor is the same as a 0.0 volt signal which indicates a lean condition. This would cause the ECU to trim by adding fuel.
  2. There appears to be a standard behaviour for closed loop systems where they default to a "mid range" rich map if the O2 sensor readings are pegged at zero for three minutes.

There's nothing bad about this because the O2 eliminator is doing what it's advertised to do, which is cause the ECU to stick with a static fuel map. However it may take three minutes for that static map to kick in. I guess that means don't tune your bike until you've been on the dyno for about five minutes with a hot engine in closed loop mode? Really it all depends on how the Honda PGM-FI ECU behaves when it sees a constant 0.0 signal from the O2 sensors, which might even be different on 2002-2005 bikes and 2006+ bikes since they have different ECU hardware!

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