Make Your Own O2 Sensor Eliminators

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Close-up of connectors

You can make your own Oxygen sensor eliminators by installing 330 ohm resisters across the leads to the OEM sensors. Locate the natural and the black colored 4p connectors near the alternator cover (left side) and dissconnect them both.

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Location under left fairing

PARTS

330 ohm resisters at Radio Shack $0.99 a pack of 5

Model: 271-1315

Catalog #: 271-1315

INSTALL

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Install the Resisters across the leads

The 4p connectos have 4 leads. Use the two leads opposite the locking tab on each of the black and natural connectors, obviously on the side connected to the bike and not to the O2 sensors. You can remove the sensors and their wire harnesses if you want. Plugs that fit where the sensors screw into the exhaust pipes are easily found at most any auto parts store.

You can wrap with electrical tape or find large shrink wrap to protect the wireing job, zip tie them secure.

Thanks for the 'how' to eliminate the O2 sensors...

What does it do for me? with a stock Vtec, no pipe or PCIII.

My guess is, it will prevent the bike from leaning itself out because it doesn't detect the rich mixture anymore.

DizzyDaveThanks for the 'how' to eliminate the O2 sensors...

What does it do for me?? with a stock Vtec, no pipe or PCIII.

My guess is, it will prevent the bike from leaning itself out because it doesn't detect the rich mixture anymore.

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I asked a similar question on another recent thread and am impatiently waiting for a response smile.gif

Here it is again to add to Dave's question:

If the 99 headers have no cat and the resistors are plugged into the O2s, what does that do to the FI without a PCIII? Does the bike run richer overall, but without the Cat produces more hp? If one were to simply run eliminators on a bike with a Cat and no PCIII, what would happen, assuming no aftermarket pipes? More hp / hurt performance / nothing? Inquiring minds want to know! I really know very little about the intricacies of the FI system and have learned a lot from some of our more technical folks at VFRD. As always, I appreciate the info!! Thanks.

It is thought that eliminating the o2 sensors cures that midrange surge or flat spot in the power-band. It is essential to eliminate the sensors when using a PCIII or you will get FI errors. Using an aftermarket silencer some have had success in curing the surging by eliminating the O2 sensors. When in constant throttle the ecm puts the fuel curve into stoichiometric mode and it burns with lower emissions, saves fuel, this seems to produce a flat spot or a surge when coming out of it.

Thanks HS. I was looking for a bit more ed-u-ma-ca-shun on how it actually worked in terms of various throttle situations so I appreciate the help. If I understand this correctly, the O2 sensors "tell" the system to richen/lean mixture as needed depending on the readings before and after the Cat. So my question is, if the Cat is not there (ie 99 header pipe) and the sensors are eliminated, does the bike run leaner, regardless of throttle state (steady, WOT) or does the bike run richer? What actually controls the fuel/air mixture on the bikes, other than the stock map and O2 sensors? It seems the removal of the Cat would decrease the restriction enough to require a change in the mixture (assuming factory exhaust and no PC III). So, to complete my ramblings, if I were to get 99 headers, with no aftermarket pipes and no PC III for my Vtec, would I notice any positive or negative performance changes (hp) or will it simply be enough to address surging problems for those unlucky owners that have them?

Map Sensor is what controls the fuel air mixture mostly, but it hands off to the O2 sensors when in open loop during those steady throttle sessions then it goes very lean into stoichometric, it think its 14 parts air 1 part fuel. Map sensor measures the manifold vacuum pressure which is what controls the fuel mix when tied with the throttle postion sensor - its a three dimensional map tp sensor vs map sensor air temp sensor in the airbox - it is when one of these variables is held constant that the O2 sensors is used, TP constant input for so many seconds loops in the o2 sensors.

It is an excorize in Boyle's law

PV=C

and adjusting for temperature

V=CT

The computer needs to know the volume of air at what pressure and temperature in the cyclinder to inject the right amount of fuel based on the throttle input at the time of the intake stroke.

It reads temperature from the temperature sensor and reads pressure with the map sensor, and then calculates the amount fuel - it is not 100% correct so there is not always an effiecient burn so when the throttle postion is held constant it can read the O2 sensor reading and inject stochometric fuel loads. Its of course more complicated than I explain but basically thats the idea.

When I installed mine I ended up nipping off a little of each lead so that the resistor can sit right on the end of the connector. Makes for a little cleaner tape job. :D

IkazuchiWhen I installed mine I ended up nipping off a little of each lead so that the resistor can sit right on the end of the connector.  Makes for a little cleaner tape job. :D

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Indeed. This was more for demo purposes, so a person could see what terminals to plug in to. I also want to mention that there is no need to mummify the connectors with electrical tape to keep water out. Just use a little bit to 1) retain the resistor and 2) insulate any metal from shorting out. Too much tape will likely trap water inside the connectors and lead to corrosion (someday). And water won't really hurt anything, anyway. Instead, let them be "self draining". Engine heat will dry 'em in a minute. Besides, once you pull that clear plastic boot back down over the connectors, water won't be an issue anyway.

I think it is all making sense now. So if I put on the new -old headers, and used the O2 sensors, I wouldn't really see much on the bike performance wise. My bike would just run closed loop at all TP and I might get a bit more sound from the stock cans? Correct? Sorry if I sound like a dumbass asking this many questions. I am just trying to squeeze as much bang-for-the-buck out of the silver bullet as possible. +1.gif

VFRquigI think it is all making sense now.? So if I put on the new -old headers, and used the O2 sensors, I wouldn't really see much on the bike performance wise.? My bike would just run closed loop at all TP and I might get a bit more sound from the stock cans? Correct? Sorry if I sound like a dumbass asking this many questions.? I am just trying to squeeze as much bang-for-the-buck out of the silver bullet as possible.? +1.gif

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HS is basically right, but to boil it down....there's no real reason to eliminate the O2s if you're NOT running a Power Commander. That is, unless you're putting any kind of "headers with no sensors" on an O2-sensored bike. In that case, you'll have to do the O2 elims to keep the FI light happy.

As a practical matter in the real world, you won't see power increases and such by O2 elimination. You don't get power increases at steady-state throttle.....where the O2's "live".

TraceHS is basically right, but to boil it down....there's no real reason to eliminate the O2s if you're NOT running a Power Commander.?  That is, unless you're putting any kind of "headers with no sensors" on an O2-sensored bike.? In that case, you'll have to do the O2 elims to keep the FI light happy.?

As a practical matter in the real world, you won't see power increases and such by O2 elimination.? You don't get power increases at steady-state throttle.....where the O2's "live".

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Sweet- thanks for all the free knowledge. Now I just have to decide if the weight savings of going Cat-less will make my ride scary fast- lol

One last thing- will the change in restriction have any negative effect on the bike? I assume the bulk of the exhaust restrict comes from the cat, not the stock pipes. I have fears that such a change may cause problems? Any comments?

From everything I've read, most people seem to be happy with o2 sensor eliminators or 330 ohm resisters. So, I decided to try it. My results were less than favorable. Now when the bike stumbles/surges in the 4k-5k range, it feels like I lose all of my power. When I twist the throttle a bit to get out of the stoichiometric mode or when the RPMs get above 5k, it feels like someone just rear-ended me as the bike lurches forward violently. sad.gif

My pretty sure I plugged the resistors into the correct spots since the FI light doesn't come on. My only guess is that I grabbed the wrong resistors from Radio Shack. The package says 330 ohm, but I'm going to check the colors on the resistor just to make sure. :huh: Until I can figure it out, I'll be removing the resistors and plugging my o2 sensors back in. <_< YMMV.

How do you arrive at a value of 330 ohms for the resistors? Is it in the manual, spec for the O2 sensor? Just curious. Thanks!

notoriousdjwHow do you arrive at a value of 330 ohms for the resistors?  Is it in the manual, spec for the O2 sensor?  Just curious.  Thanks!

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I think someone actually measured the dynojet branded eliminators.

notoriousdjwHow do you arrive at a value of 330 ohms for the resistors?? Is it in the manual, spec for the O2 sensor?? Just curious.? Thanks!

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Dunno. It's just been "common knowledge" since forever. O2 elims are very common in the aftermarket world, so it's not any real secret as to what is in those $15 (each) items from DynoJet. I'm sure sombody just laid an Ohm meter on one, took the reading, made their own.

MFP-2241Now when the bike stumbles/surges in the 4k-5k range, it feels like I lose all of my power.  When I twist the throttle a bit to get out of the stoichiometric mode or when the RPMs get above 5k, it feels like someone just rear-ended me as the bike lurches forward violently. 

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I take it you don't have a PC? Again, there's no reason to remove the O2s unless you do.

TraceI take it you don't have a PC?  Again, there's no reason  to remove the O2s unless you do.

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Yup no PC. I was under the impression that the O2 eliminator merely kept the bike from enter stoichiometric mode when holding a constant throttle. How does a PC keep the bike from stumbling if the ECU is always trying to adjust the air/fuel ratio at constant throttle? I thought all the PC did was allow you to dump more or less fuel into the cylinders at given throttle openings. Wouldn't the ECU still try to fight with the PC then? I'm confused. :unsure:

MFP-2241Yup no PC.? I was under the impression that the O2 eliminator merely kept the bike from enter stoichiometric mode when holding a constant throttle.? How does a PC keep the bike from stumbling if the ECU is always trying to adjust the air/fuel ratio at constant throttle?? I thought all the PC did was allow you to dump more or less fuel into the cylinders at given throttle openings.? Wouldn't the ECU still try to fight with the PC then?? I'm confused.?

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Yes, you are confused.

The PCII simply "fools" the ECU into thinking it's happy, so there's no fighting each other under your seat! +1.gif It does this by providing the ECU with bogus input data at various throttle and rpm points, most noteably as HS said above, the MAP sensor. The ECU interprets this bogus data and acts accordingly. The trick is to give it "good" bogus data so it does what you want. The O2s try to undo what you're tricking....and it can try to go either way. O2s don't just lean things out....they can richen them from a lean condition, too. I suspect that's what happened in MFP-2214's case....but dunno for sure.

So, there you have it. Buy a PC and do the 330 ohm trick....and save $30!! :thumbsup: :P

I urge you to go to the DynoJet website and mouse around there for awhile. They explain the differences between PCII, III, IIIusb, etc....and much other info as to how these things work.

I installed the resistors two weeks ago on a stock 2003, no PC. It almost completely did away with the slight feeling of power loss between 4500 and 5k at a constant throttle that I was noticing before.

JKirkI installed the resistors two weeks ago on a stock 2003, no PC. It almost completely did away with the slight feeling of power loss between 4500 and 5k at a constant throttle that I was noticing before.

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Now THAT's interesting!! Dunno.

TraceYes, you are confused. 

The PCII simply "fools" the ECU into thinking it's happy, so there's no fighting each other under your seat!  :goofy:  It does this by providing the ECU with bogus input data at various throttle and rpm points, most noteably as HS said above, the MAP sensor.  The ECU interprets this bogus data and acts accordingly.  The trick is to give it "good" bogus data so it does what you want.  The O2s try to undo what you're tricking....and it can try to go either way.  O2s don't just lean things out....they can richen them from a lean condition, too.  I suspect that's what happened in MFP-2214's case....but dunno for sure.

So, there you have it.  Buy a PC and do the 330 ohm trick....and save $30!!  :thumbsup:  :P

I urge you to go to the DynoJet website and mouse around there for awhile. They explain the differences between PCII, III, IIIusb, etc....and much other info as to how these things work.

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This is not really correct. The Power Commander does not alter the inputs to the ECU. It sits between the ECU and the injectors...It intercepts the injector control pulses from the ECU, modifies them to achieve the desired trim based upon the custom map, then sends them on to the injectors. The ECU still gets normal input data and does whatever it does with that to generate a base injector pulse for those conditions. The PC stretches or shortens the base pulse to achieve the desired fuel trim. (Remember...Injectors are a pulse-width modulated device. The longer they are "on" the more fuel they will deliver -> richer mix)

MFP-2241From everything I've read, most people seem to be happy with o2 sensor eliminators or 330 ohm resisters.  So, I decided to try it.  My results were less than favorable.  Now when the bike stumbles/surges in the 4k-5k range, it feels like I lose all of my power.  When I twist the throttle a bit to get out of the stoichiometric mode or when the RPMs get above 5k, it feels like someone just rear-ended me as the bike lurches forward violently.  sad.gif

My pretty sure I plugged the resistors into the correct spots since the FI light doesn't come on.  My only guess is that I grabbed the wrong resistors from Radio Shack.  The package says 330 ohm, but I'm going to check the colors on the resistor just to make sure.  +1.gif   Until I can figure it out, I'll be removing the resistors and plugging my o2 sensors back in.  <_<  YMMV.

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MFP, when I first put in the O2 sensor eliminators which I purchased for 30 bucks on my Vtech I had the same problem as you described as did a few others on the board. The lurching was terrible. However, I discovered that by turning the ignition on, letting it go through it's whine, then turn it off and then back on and then start the engine, the surging and flat spot are completely eliminated. Why does this happen? No f ing clue. Some think that the computer resets itself after you shut down the bike each time. By "rebooting" the computer it seems to read the open loop. I think Das Bone has documented this too. So leave them in and just on/off/on your bike each time. Beats spending 300 bucks on a PC111.

kerplodeThis is not really correct.  The Power Commander does not alter the inputs to the ECU.  It sits between the ECU and the injectors...It intercepts the injector control pulses from the ECU, modifies them to achieve the desired trim based upon the custom map, then sends them on to the injectors.  The ECU still gets normal input data and does whatever it does with that to generate a base injector pulse for those conditions.  The PC stretches or shortens the base pulse to achieve the desired fuel trim. (Remember...Injectors are a pulse-width modulated device.  The longer they are "on" the more fuel they will deliver -> richer mix)

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Yes, it IS correct for the PCII, which is what I was addressing. Sorry, should have been totally specific. From the DynoJet website:

The Power Commander II was introduced in 1999 and featured the latest surface mount electronics. Additional features were added like the faceplate button adjustment. The Power Commander II also allowed fuel and ignition adjustment on select models. The PCII utilizes "sensor offset" technology to adjust the fuel curve. Signals from the various sensors on the bike are monitored by the PCII and these signals are recalculated and sent to the ECU in order to achieve the required fuel curve.

And the PCIII operates like this, as kerplode said:

The Power Commander III was introduced in 2000 and is externally similar to the PCII. The PCIII utilizes "direct injector control" technology to control the fuel curve for models that do not possess the appropriate sensors to allow sufficient fuel adjustment using the PCII technology. The PCIII takes the injector pulse from the ECU and changes the pulse width signal to the injectors.This unit allows "Fuel Only" adjustment.

For my money, I'll take the PCII, which allows me to tinker with timing and two other sensor inputs.

More at for the other versions, such as USB at: http://www.powercommander.com/featversions.shtml

quicknickMFP, when I first put in the O2 sensor eliminators which I purchased for 30 bucks on my Vtech I had the same problem as you described as did a few others on the board. The lurching was terrible. However, I discovered that by turning the ignition on, letting it go through it's whine, then turn it off and then back on and then start the engine, the surging and flat spot are completely eliminated. Why does this happen? No f ing clue. Some think that the computer resets itself after you shut down the bike each time. By "rebooting" the computer it seems to read the open loop. I think Das Bone has documented this too. So leave them in and just on/off/on your bike each time. Beats spending 300 bucks on a PC111.

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:blink: Ok, I'll give it a try then. :thumbsup:

Yea the PC2 would alter the sensor inputs before they went into the ECM, but the PC3 is after the ECM actually altering the input to the injectors directly.

That is the main difference between the older PC's and the new ones. Still need to eliminate the O2 sensors when using the PC3 though, the PC2 is for the first generation of fuel injection like my 98vfr that did not have O2 sensors, later in 2000 when the yellow bike came out they went to using O2 sensors and the PC3 came out for that bike

USING only O2 elmininators will prevent the bike from going into stocimetric mode and is said to smooth out the throttle responce like I said earlier. but I have no experience with that so take it at face value.

Yes, it IS correct for the PCII, which is what I was addressing.

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Hey cozye,
Had the resistors installed properly and the code for them is gone.  One problem is the Fi light still came on, first very light and then brighter and brighter.  Then noticed that it blinks with the turn signals, gets bright with the brake, horn etc, so have a short somewhere on the ground side.  Most likely a loose connection.  Will hunt for it this weekend.  It quit stalling out when warm, so the puter must like the resistors.  Thanks for the help.

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Finally figured it out (without breaking it!) and got my resistors and PC III installed. Loaded up BenSV's map and WOW!!! A different motorcycle. No more herky jerky at low speeds and no more dreading the VTEC kick-in. It's raining like heck today, so I only did about 10 miles to check it out. Thanks to all who contribute here.

Julie

Hi. I am new to the forum and new to the VFR but not at all new to bikes. I found the cheapest solution for the loss of power in the 5k range at constant throttle.............twist it a little bit more and keep it up in Vtec mode! If its too fast try a lower gear.......free and seems to work well for me! :idea3:

So 330 ohm resistance OK

the guy at the shop asked me what wattage, what is it?

This may be too obvious for most, but I need to ask.
Once you have installed the 330 ohm resistors, can you remove the opposite plug ends right down to the pipes?
I beleive I read once on a lost thread, that you can plug off where the sensors tap into the pipes, before the cat.

Is this true? If so, what might one suggest is the best plugging method (if other than just a suitable bolt)?

Thank you.

I'll let you know what I find.

Really appreciate the guidance.

Thank you.

I'll let you know what I find.

Really appreciate the guidance.

I believe it was 18MM drain plugs from Autozone and some copper washers that worked for me. Just take one of the sensors with you and match up the threads.

However, I discovered that by turning the ignition on, letting it go through it's whine, then turn it off and then back on and then start the engine, the surging and flat spot are completely eliminated. Why does this happen? No f ing clue. Some think that the computer resets itself after you shut down the bike each time. By "rebooting" the computer it seems to read the open loop. I think Das Bone has documented this too. So leave them in and just on/off/on your bike each time. Beats spending 300 bucks on a PC111.

I have tried this and this really works, the bike feels and sounds a lot smoother but a flatspot betwen 4k-5k rmp , but why !!! Any one got a clue why it's possible to do this with the ECU. Is there any hidden test modes to set up the ECU in, or perhaps some feature that don't got to the consumer lines.
And for the "I think Das Bone has documented this too" can't find it, can you give me any directions ... :goofy:

!! parden my english it's not my native language !!

I have tried this and this really works, the bike feels and sounds a lot smoother but a flatspot betwen 4k-5k rmp , but why !!! Any one got a clue why it's possible to do this with the ECU. Is there any hidden test modes to set up the ECU in, or perhaps some feature that don't got to the consumer lines.
And for the "I think Das Bone has documented this too" can't find it, can you give me any directions ... :unsure:

!! parden my english it's not my native language !!

From another post that I posted yesterday:

Apparently the ECU isn't fooled by the O2-eliminator mod and when it enters closed loop mode, it tries to adjust the air/fuel ratio. Unfortunately, any adjustments the ECU makes won�t register because the O2-eliminators are sending a constant signal to the computer. So the ECU continues to adjusts the air/fuel mixture in a vain attempt to reach the stoichiometric ratio and it eventually leans out the air/fuel mixture so much that the engine loses a ton of power. When you twist the throttle a bit, the ECU leaves closed loop mode and goes back to the default map. The engine suddenly makes power again and the bike lurches violently forward.

Ironically, the O2-eliminators are suppose to make the ECU think everything as just fine when it enters closed loop mode, but it instead has cause some bikes to surge severely.

The trick around this is to prevent the bike from entering closed loop mode. This can be achieved by starting the bike before the ECU has a chance to complete its boot up cycle.

Now, when you turn the ignition on, you see the digital gauges flash on once and then display normally. I believe this is caused by the ECU going though a boot up cycle. If you start the bike before the ECU finishes its boot up cycle, then it won�t go into closed loop later. My guess is that by starting the bike before the ECU boots up causes an error in the ECU. To protect the bike, the ECU loads the default map and sticks with it. So, once you turn the ignition on, start your bike immediately and you shouldn�t have any more surging issues. (Likewise, there�s no reason this wouldn�t work for bikes without O2-eliminators either).

This is my start up procedure (which seems to work very well to avoid this surging problem):

1) Turn ignition on.
2) Put the bike into neutral.
3) Wait for the fuel pump to prime the fuel system.
4) Once FI system is primed, then in quick secession: turn ignition off, push the starter button, turn ignition on, release starter once bike starts.

PorradaVFR, Feb 28 2008, 01:37 AMGiven 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?

Capflamme, Feb 28 2008, 10:58 AM

PorradaVFR, Feb 28 2008, 01:37 AMGiven 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?

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.

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?

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.

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.

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.

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 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 Posted Image

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

• 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.
• 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.

kaldek

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.

Hmm, I might be wrong on this. There are a lot of folks selling things called EFIE or "Electronic Fuel Injection Enhancer" which is used by people running HHO systems, and these little boxes send a customised voltage fluctuation to the ECU so that the ECU sees a falsified O2 sensor signal that forces the car's ECU to push a lean or rich trim. If you altered the O2 signal a bit to show a leaner signal than it's truly detecting, then I suppose you could use the same kind of thinking to tweak the output signal of the O2 sensor so that the resulting fuel mixture was right about 13.6 AFR, even with a narrowband O2 sensor.

Again the only reason I can think that Dynojet is doing these O2 optimizers would be because the ECU on some bikes flashes a fuel injection error code when it sees a permanent 0.0 signal from an O2 sensor, which is what happens when you use an O2 eliminator.

I just couldn't leave it alone, so I made an O2 sensor video.

Great video... that clears a lot of things up. I've got gotten an '02 VFR, and I'm mapping out a modification plan of attack. The whole PC + O2 eliminator mod was throwing me off a bit, but now I think I've got it straight. Thanks!

So does the PCV allow timing changes on my y2k vfr? Earlier it was said that PCIII cannot do timing adjustments... And timing is essential to gaining the most power, adding fuel only gets you so far before you need to adjust the timing

hey,

don't spose you guys know if this Lil trick with the o2 eliminators will work over here in the uk?

Darth Bling

tjvfr800

I have tried this and this really works, the bike feels and sounds a lot smoother but a flatspot betwen 4k-5k rmp , but why !!! Any one got a clue why it's possible to do this with the ECU. Is there any hidden test modes to set up the ECU in, or perhaps some feature that don't got to the consumer lines.

And for the "I think Das Bone has documented this too" can't find it, can you give me any directions ... :goofy:

!! parden my english it's not my native language !!

From another post that I posted yesterday:

Apparently the ECU isn't fooled by the O2-eliminator mod and when it enters closed loop mode, it tries to adjust the air/fuel ratio. Unfortunately, any adjustments the ECU makes won’t register because the O2-eliminators are sending a constant signal to the computer. So the ECU continues to adjusts the air/fuel mixture in a vain attempt to reach the stoichiometric ratio and it eventually leans out the air/fuel mixture so much that the engine loses a ton of power. When you twist the throttle a bit, the ECU leaves closed loop mode and goes back to the default map. The engine suddenly makes power again and the bike lurches violently forward.

Ironically, the O2-eliminators are suppose to make the ECU think everything as just fine when it enters closed loop mode, but it instead has cause some bikes to surge severely.

The trick around this is to prevent the bike from entering closed loop mode. This can be achieved by starting the bike before the ECU has a chance to complete its boot up cycle.

Now, when you turn the ignition on, you see the digital gauges flash on once and then display normally. I believe this is caused by the ECU going though a boot up cycle. If you start the bike before the ECU finishes its boot up cycle, then it won’t go into closed loop later. My guess is that by starting the bike before the ECU boots up causes an error in the ECU. To protect the bike, the ECU loads the default map and sticks with it. So, once you turn the ignition on, start your bike immediately and you shouldn’t have any more surging issues. (Likewise, there’s no reason this wouldn’t work for bikes without O2-eliminators either).

This is my start up procedure (which seems to work very well to avoid this surging problem):

1) Turn ignition on.

2) Put the bike into neutral.

3) Wait for the fuel pump to prime the fuel system.

4) Once FI system is primed, then in quick secession: turn ignition off, push the starter button, turn ignition on, release starter once bike starts.

Has this been confirmed? It seems there are people out there that don't go through this procedure and everything is great. Myself however, when I hold throttle and go into closed loop mode (I have a PCV), I start to lose power! This post is rather old so I am trying to see if there is some more information learned by now since then. One theory of mine is that one or two of my o2 eliminators (they came with the PCV) may be bad.

I have done this mod today and can only say this: WAUW!

It's brilliant, not only makes it the pairing mode obsolete but it also makes the bike respond well from about 2500 rpm.

I have done some serious digging and you do not need a power-commander or anything to feel the difference.

What this mod does is simple, it tell the ECU that your Lambda-sensor is connected, nothing more nothing less.

A working sensor does provide a voltage to the ECU to what the ECU responds by using some sort of mapping.

Because the mod omits the voltage, the ECU will think the sensor is broken, it knows this after about 3 minutes.

You can smell this during starting as the ECU keeps pumping extra fuel that doesn't ignite well, as such the exhaust will smell a lot after petrol.

As the ECU notices that the "sensor" doesn't respond to it's regulation it assumes it's broken and starts a special optimized combustion-program that has static parameters.

This special program is optimal, and you know it as the power is there and the response is brilliant!

It's also this program that the power-commder uses to control the injection.

However, you do not need a power-commander, the optimal program is already in the ECU and works as expected.

There is instantly a lot of extra power and torque, if you wait 3 minutes after starting.

I have done this mod on a VFR800Fi 2000 and a CBR1000RR, and on both machines the results are great.

Also, this mod makes the ECU just respond to the throttle and not to the O2/CO2-level anymore, as it thinks the sensor is broken.

Yes when you start it smells bad, but it quickly returns to normal with an improved riding experience.

signal

One theory of mine is that one or two of my o2 eliminators (they came with the PCV) may be bad.

Your "eliminator" is nothing more then a ~330Ohm resistor, nothing more, you can measure it.

Remove it, then measure the 2 pins (normally connected to the white O2-sensor wires) and it should read about 330~1000Ohm.

These "eliminators" do nothing more then fool the ECU that an O2-sensor is present, that is it.

They do not eliminate anything.

Because if you forget them, it will make your FI-light come on and the ECU tells you something is wrong, however that also means you miss any real important problem with your bike.

You do not want the FI-light on all the time, telling you the bike has a problem :cheerleader:

I did this recently, love it. The biggest difference is improving the flat spot before hyperdive.

Just wanted to say thanks to Trace for this write up. Seven and a half years later you are still saving VFR owners (me) money. Thanks!

^ me too ^ :beer:

Bassie

I have done this mod today and can only say this: WAUW!

It's brilliant, not only makes it the pairing mode obsolete but it also makes the bike respond well from about 2500 rpm.

I have done some serious digging and you do not need a power-commander or anything to feel the difference.

What this mod does is simple, it tell the ECU that your Lambda-sensor is connected, nothing more nothing less.

A working sensor does provide a voltage to the ECU to what the ECU responds by using some sort of mapping.

Because the mod omits the voltage, the ECU will think the sensor is broken, it knows this after about 3 minutes.

You can smell this during starting as the ECU keeps pumping extra fuel that doesn't ignite well, as such the exhaust will smell a lot after petrol.

As the ECU notices that the "sensor" doesn't respond to it's regulation it assumes it's broken and starts a special optimized combustion-program that has static parameters.

This special program is optimal, and you know it as the power is there and the response is brilliant!

It's also this program that the power-commder uses to control the injection.

However, you do not need a power-commander, the optimal program is already in the ECU and works as expected.

There is instantly a lot of extra power and torque, if you wait 3 minutes after starting.

I have done this mod on a VFR800Fi 2000 and a CBR1000RR, and on both machines the results are great.

Also, this mod makes the ECU just respond to the throttle and not to the O2/CO2-level anymore, as it thinks the sensor is broken.

Yes when you start it smells bad, but it quickly returns to normal with an improved riding experience.

The only thing with mine, I am not sure it resets after 3 min. seems to always be rich gassy does not run hot, no hotter than VFR's do anyways....

VTECLiam

hey,

don't spose you guys know if this Lil trick with the o2 eliminators will work over here in the uk?

I've had O2 eliminators on my 08 for a couple of years now. No PC fitted, no other engine mods and I do believe it makes the bike run better at low revs. Mind you, so does a good SV balance. And it's a very subjective assessment.

I'm going to try the ignition ON/OFF/ON thing mentioned above and see if that makes a difference to the quiet spot ~5krpm.

Skids

VTECLiam

hey,

don't spose you guys know if this Lil trick with the o2 eliminators will work over here in the uk?

I've had O2 eliminators on my 08 for a couple of years now. No PC fitted, no other engine mods and I do believe it makes the bike run better at low revs. Mind you, so does a good SV balance. And it's a very subjective assessment.

I'm going to try the ignition ON/OFF/ON thing mentioned above and see if that makes a difference to the quiet spot ~5krpm.

Tried it, twice, this morning, before & after refuel on the way to work (35 miles, town & highway). Whilst I'm not 100% convinced yet I'm pretty sure there is less of a "lack of drive" from 4500-6000-ish rpm. Certainly in 6th gear, the roll on from ~5krpm feels smoother and more linear.

Surely it can't be that easy?

I'm going to carry on trying this for a few more days then revert back to normal start procedure and see if I can spot a difference.

Thank you, thank you, thank you!!!! First time posting and this was my first performance mod. It is sooooooo much smoother now. Mind you, this is actually my first bike, so I just thought the rough ride at low revs was a lack of skills (and that may still be the case). I had considered the PAIR and flapper mods but I think I will quit while ahead. If I understand correctly, I believe this mod is the alternative to the PAIR mod. I know zero about mechanics. Thanks to the creator of this post and everyone else for your feedback.

Since this is my first official post, I included a pic of my 2007 VFR (I hope it works - having trouble posting pic). Thanks for all of the advice. I couldn't continue lurking with a clean conscious without acknowleding the forum for all of the great advice and humor. :)

P.S. The exhaust was done today; O2 mod completed a couple of days ago. Delkevic mini carbons.

[image: DJCheez VFR3]

DJCheez1

Thank you, thank you, thank you!!!! First time posting and this was my first performance mod. It is sooooooo much smoother now. Mind you, this is actually my first bike, so I just thought the rough ride at low revs was a lack of skills (and that may still be the case). I had considered the PAIR and flapper mods but I think I will quit while ahead. If I understand correctly, I believe this mod is the alternative to the PAIR mod. I know zero about mechanics. Thanks to the creator of this post and everyone else for your feedback.

Since this is my first official post, I included a pic of my 2007 VFR (I hope it works - having trouble posting pic). Thanks for all of the advice. I couldn't continue lurking with a clean conscious without acknowleding the forum for all of the great advice and humor. :)

P.S. The exhaust was done today; O2 mod completed a couple of days ago. Delkevic mini carbons.

Dude Welcome love that paint scheme. Is dark gray painted ?

Need to do a introduction post .

Thanks @Switchblade. The black/grey is vinyl. Nice cover for the scratches the PO put on there.

Found these while looking for a exhaust system.

[image: EL00017_2.JPG]

$15.10

https://www.dan-moto.com/DM_INT/index.php?main_page=product_info&cPath=129_141&products_id=826

Switchblade

Found these while looking for a exhaust system.

[image: EL00017_2.JPG]

Honda VFR 800 1998-2010

Model: EL-00044 Unit Price: USD

$15.10

https://www.dan-moto.com/DM_INT/index.php?main_page=product_info&cPath=129_141&products_id=826

You must have forgotten what the thread was about. Two resistors costing just a few cents each do the same job.

tbzep

Switchblade

Found these while looking for a exhaust system.

[image: EL00017_2.JPG]

Honda VFR 800 1998-2010

Model: EL-00044 Unit Price: USD

$15.10

https://www.dan-moto.com/DM_INT/index.php?main_page=product_info&cPath=129_141&products_id=826

You must have forgotten what the thread was about. Two resistors costing just a few cents each do the same job.

No did not forget but for $20.00 to the door I wouldn't make mine .

Switchblade

tbzep

Switchblade

Found these while looking for a exhaust system.

[image: EL00017_2.JPG]

Honda VFR 800 1998-2010

Model: EL-00044 Unit Price: USD

$15.10

https://www.dan-moto.com/DM_INT/index.php?main_page=product_info&cPath=129_141&products_id=826

You must have forgotten what the thread was about. Two resistors costing just a few cents each do the same job.

No did not forget but for $20.00 to the door I wouldn't make mine .

You would spend $20 over $1? There's no "making" to them. Just snip the excess length off the leads and stick them in there. Add a little bit of tape to keep them from falling out and you're done.

tbzep

Switchblade

tbzep

Switchblade

Found these while looking for a exhaust system.

[image: EL00017_2.JPG]

Honda VFR 800 1998-2010

Model: EL-00044 Unit Price: USD

$15.10

https://www.dan-moto.com/DM_INT/index.php?main_page=product_info&cPath=129_141&products_id=826

You must have forgotten what the thread was about. Two resistors costing just a few cents each do the same job.

No did not forget but for $20.00 to the door I wouldn't make mine .

You would spend $20 over $1? There's no "making" to them. Just snip the excess length off the leads and stick them in there. Add a little bit of tape to keep them from falling out and you're done.

All ready have a set of home made .

Oops, we've been quoting the image every time. :goofy:

Very very few people I suspect have ridden the VTEC VFR the way Honda engineers meant it to be ridden. Coderighter, you gotta hack that ECU, brother.

Meanwhile, I dunno, I've always been a carb guy, don't know nothing bout no fuel injection. But it just seems to me, this beast is too lean down low; it hesitates when you crack open the throttle and I think the overrun shutoff aggravates this. I do think richening things up will help, but that becomes a mapping issue and maybe the default map will work for you and maybe it won't. (With the idea being, by disabling the 02 sensors you are forcing the default map.)

If it doesn't, you can go the Coyze route and make it rich AND smooth, or you can go the Coderighter route and try to make it perfect. (Referring to PC maps.)

But I gotta think there are some ECU's locked in a safe somewhere in Japan that make this the best bike ever made. And dammit, I want one.

If you want to ride the bike how the Honda engineers designed it to be ridin, put a Rapid Bike Racing module on it and install the optional 4 wide band o2 sensors. The included base ignition and fuelling map will get you pretty close to perfect and after about 200 miles you'll swear that you have never riden anything so smooth in your life. The VTEC transition, snatchy throttle and surging completely disappear.

Also the ignition remapping adds a significant amount of low end and midrange torque everywhere and the engine braking adjustment feature gets rid of the factory fuel cut that you were talking about.

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 !

@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. 

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

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.

Will this work on Honda Shadow VT750 C2B?

Will this work on Honda Shadow VT750 C2B?

Yeap .

And Welcome .