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Discussion Starter #1 (Edited)
Here's further rainy weekend reading for you, with yet another Bugger-all-Power© mod from Forchetto...:)

In my quest for improved driveability and refinement I have now done such mods as an external crankcase breather, airbox mods including Unifilter, re-located IAT sensor and cold air intake bellmouth and AI elimination.

These, together with my Arrow 2-2 exhaust system with 020264 map with cut-down baffle and drive chain adjustment to the revised specs of 15-30 mm slack, have produced a bike that is even more of a pleasure to drive than it ever was. No more snatch or surging and a refinement worthy of a Bentley. I won't claim power increases, but the old butt-dyno does indicate that things are running better.

There's one more mod done to acomplish this that I haven't detailed here as I've waited a few weeks for long term testing before daring to display it here: The elimination and bypass of the O2 sensors (Oxygen or Lambda sensors).

As you all know these devices are rather clever exhaust "sniffers" that produce a voltage proportional to the oxygen content in the exhaust and inform the ECM which in turn adjusts the fuelling to try to maintain the ideal low-emissions Air-fuel ratio of 14.7:1, also called "Lambda 1". This ratio is great for the environment and essential for the correct functioning of catalytic converters, but it tends to interfere with the fuelling below about 6% of throttle opening and steady low speed cruising. This is known as "closed-loop running".

The same driveability effects like jerkyness, a hairy throttle response and hunting on steady loads are not really noticeable in cars given the greater mass of their flywheels, more cylinders and the mass and therefore inertia of the vehicle itself. On a bike they can be a right PITA as evidenced by general moans across all forums dealing with EFI equipped machines.

There are several ways to eliminate these sensors:

1.- If you fit a Power Commander they'll include a couple of dummy plugs containing some resistors to fool the ECM that the sensors are still there. This is because there's no point in the Power Commander modifying the fuelling if the sensors detect this and force the Air-fuel ratio to return to normal, emissions-friendly level.

The sensors themselves can remain on the bike, but their connectors have to be disconnected and tied up somewhere. See post nº2 from pieman for further advice on not leaving the sensors fitted.

2.- If you have the Tuneboy software and cable, then the sensors are bypassed electronically with the program and the ECM no longer looks for them. The devices themselves can once again remain fully connected up on the bike but, as pointed out, it's best to remove altogether. Tuneboy is the only tool that can switch off the O2 sensor in the ECU.

3.- Having your ECM re-mapped by Mike (Pieman) will also result in the bypassing of the sensors by software.

4.- The fourth option is what I've done, and what this post is about. This is to remove the sensors altogether and fit blanking plugs to their bosses in the exhaust downtubes. The fuelling then reverts to whatever the main map says, in my case (map 020264) this appears to be about 13.2-13.5:1, much better for good idle and smooth low speed running. This was measured with my rather basic AFR meter.

We can't just disconnect the plugs and leave it at that. The ECM will instantly detect the lack of sensors, first by not finding the sensor's built-in heaters and if we fool it by fitting suitable resistors to the heater terminals it'll then find, after a short time, that it's not receiving a suitable signal from the sensor itself. Both situations light up the engine malfunction indicating light (MIL).

After much searching, as there's virtually no info on Bonnevilles, and the Dynojet O2 sensor eliminators sold by the likes of Triumph-online.co.uk are totally useless for us, I mean the ones advertised are not even the right bloody connector...and only one resistor is fitted, whereas we need two. Had to send them back.

Don't buy these dummy plugs. They claim they're suitable for Bonnevilles but they're not even the right type of plug, can't remember exactly but they're horrendously expensive for what they're and you have to buy two. (There are two O2 sensors on the bikes).
I deduced suitable values for these resistors from reading and researching on a multitude of contradictory posts and sites, and came up with the following values:

For the heater bypass (Brown/Pink and White wires) 330 Ohms, and for the signal bypass (Black and Pink/Black wires) 1000 Ohms.

Note that these colours are different on the sensor and bike wiring loom side. See this detail of the wiring for the EFI Bonnies, where item 11 is the left hand sensor and item 56 the right hand one:



The heater bypass resistor at 330 Ohms disipates a little less than 0.5 watt, whereas the real heater itself consumes something like 25 watts each, so this is a fair, albeit temporary load that we get rid off. The sensor heaters are fitted to enable rapid warm-up of the sensor so it's ready to work in controlling fuelling very soon after starting from cold. Once hot the heaters are turned off by the ECM, but those 50 watts are being consumed while you're trying to crank a cold engine so their removal helps a bit.

The signal bypass can be a very small resistor, 1/4 watt or higher. No great current flows through that.

I've opted for fitting comparately huge resistors, not because they're electrically required, but because larger components tend to be sturdier and have thicker leads. I've used ceramic-coated 6 watt resistors for each value. They're a tight fit but they'll never break under the conditions found on the bike. There are similar, much smaller ceramic resistors of around 2.5 watt which in hindsight might have fitted in a neater manner but it's done now.

As after much searching I couldn't find suitable connectors, and rather than cut off the ones attached to the sensors I hit on the following idea: The terminals inside the connector that stays on the wiring loom have 2mm wide 0.5mm thick blade-type contacts, so I reasoned that a Fast-on tab crimp terminal of 0.110" width would make fine tight contact and it does. The resistor wire lead is doubled-up to fill the crimp barrel fully and crimped with the correct tool. See photo for details of wire colours for correct connection of bypass resistors.





The connectors, together with the two resistors in each, are then sealed inside a weatherproof heatshrink sleeve and its open end is sealed by pressing with a pair of pliers while still hot from the hot air-gun.



The sensors themselves have been removed from the downpipes and their holes plugged with two M12 x 1.25 bolts shortened to 10 mm thread length, and fitted with 12mm copper sealing washers. Anti-seize compound was used on the threads to ease future removal. This alone might make a significant exhaust flow improvement. The sensor probes occupied a fair bit of area right inside the downpipe, whereas the blanking bolts don't protrude inside at all.



Once again, as with most of my mods, this is not invasive and you can go back to standard by just removing the resistors and replacing the sensors.

I feared an increase in fuel consumption with all these changes, primarily because the re-positioning of the IAT sensor should send the ECM signals to richen the mixture and the O2 sensors are no longer weakening the Air-fuel ratio, but the last fill-up produced the best figures on my bike so far:

5.26 Litres/100 km (53.7 MPG UK, 44.72 MPG US) In mixed town, country road and dual-carriageway.

I'm only speculating, but I think this could be due to the greater efficiency of the cold air intake, the accurate signals now being sent to the ECM by the IAT sensor and maybe the Unifilter. This results in a smaller throttle opening for the same speeds and acceleration. I can't be sure though.

Cold air intake thread can be seen here:

http://www.triumphrat.net/twins-technical-talk/141844-cold-air-intake.html

It has been updated to show a new, shorter bellmouth with photos on this post:

http://www.triumphrat.net/twins-technical-talk/141844-cold-air-intake-3.html#post1589238
 

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Nice mod Forchetto. Just one thing, don't leave disconnected O2 sensors in the pipes. With the heaters disconnected the sensors will become junk in a couple of thousand miles and if in the future you wanted to reconnect them for any reason, you'd have to buy replacement units. Always remove them and fit blanking plugs just as you have done.
 

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certainly appreciate these posts, keep them coming

now the creeping and flattery is over, can you make another set and ship them to dear old blighty pretty please
 

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Forchetto - I appreciate that you have satisfied the MIL part of the issue of disconnecting the sensor
But I suspect that is not the whole story.
This is my perception:
By connecting the actual sensor input via the 1K ohm resistor the input is being clamped to OV and you are effectively telling the ECM that the fuel is considerably lean.
That should be having the effect of adjusting the trims to supply more fuel, which will result in over rich condition. I'm not sure at what point it will saturate, but because the (simulated) 'O2' signal continues to think it is lean, it will continue to try to add more fuel. As I say, however, I am not sure where the limit on this is. I know there is a limit on how much you can manually adjust the trim in TuneBoy/TuneECU, but don't know what the dynamic effect is.
Of course it will only trim while at closed or small throttle opening, so during regular riding, it won't be 'trimming'. However the more time spent at idle, will presumably produce a higher trim.
Does your DealerTool report the fuel trim value? It would be interesting to see that.

Ideally, what you would have is a simulator that inputs a fixed voltage of 0.45V

Note that for the Triumph Sprint (also Keihin ECM) Power Commander supplies an "O2 Optimizer" - now this is purely speculative, but I suspect that 'box' shown in the picture below, contains more than just a couple of resistors and is regulated supply of 0.45V to the ECM

 

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Will this mod only work if the A.I system has been removed, re-mapped etc or will it work on a standard set up, ironing out the snatching?
 

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Discussion Starter #6 (Edited)
Forchetto - I appreciate that you have satisfied the MIL part of the issue of disconnecting the sensor
But I suspect that is not the whole story.
This is my perception:
By connecting the actual sensor input via the 1K ohm resistor the input is being clamped to OV and you are effectively telling the ECM that the fuel is considerably lean.
That should be having the effect of adjusting the trims to supply more fuel, which will result in over rich condition. I'm not sure at what point it will saturate, but because the (simulated) 'O2' signal continues to think it is lean, it will continue to try to add more fuel. As I say, however, I am not sure where the limit on this is. I know there is a limit on how much you can manually adjust the trim in TuneBoy/TuneECU, but don't know what the dynamic effect is.
Of course it will only trim while at closed or small throttle opening, so during regular riding, it won't be 'trimming'. However the more time spent at idle, will presumably produce a higher trim.
Does your DealerTool report the fuel trim value? It would be interesting to see that.

Ideally, what you would have is a simulator that inputs a fixed voltage of 0.45V

Note that for the Triumph Sprint (also Keihin ECM) Power Commander supplies an "O2 Optimizer" - now this is purely speculative, but I suspect that 'box' shown in the picture below, contains more than just a couple of resistors and is regulated supply of 0.45V to the ECM
I'm a bit in the dark about what the AFR is at idle now. I have since screwed the sensors back in just to measure the voltage they produce when not connected to the ECM, and hopefully deduce from that the degree of richness. The readings, once heated up, are in the region of 780 to 800 mV which translates to an AFR of around 13.2:1. This holds steady for as long as it's idling.

During my searches for a solution I did come across several circuits that substitute the sensors and generate a pulsed voltage that can be adjusted to obtain the AFR required, these circuits usually have as a base the ubiquitous 555 timer chip. Something like this:



Some, for cars, are a lot simpler but for the life of me I can't see what they do:



There are lots of comercial O2 eliminators, which, I suspect, are like the first circuit shown, but as we need two I thought this was unnecessarily complicated. The makers write-up with its extravagant claims put me off.

Just feast your eyes on this beauty, noting that we need two of them. They sell for anything from $70 to as much as $200 depending on where you buy it from:

http://www.magnumtuning.com/en/product_text/adjustable_o2_oxygen_sensor_simulator_for_hho_systems1

 

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Discussion Starter #7 (Edited)
Will this mod only work if the A.I system has been removed, re-mapped etc or will it work on a standard set up, ironing out the snatching?
The only other poster as far as I know that has removed the O2 sensors is JohnnyC, but he has other airbox mods and a Pieman remap.

Having incorporated mods such as AI removal, cold air intake, re-location of IAT sensor, foam filter, no O2 sensors, Arrow exhaust and map, idle set at 1100 RPM, minimum slack on throttle cable, etc, I can't tell which mod has done what or if the present fine running is the result of all the mods together.

The one mod with which the results were instantly noticeable was the reduction of drive chain slack to the new revised figure of 15-30 mm. This made a lot of diference to the snatching and improved gearchanging.
 

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Nice job and very good explanation of what you did. I also found on my 2010 Speedy with the Power Commander that I installed then made a little heavier on the fueling due to a snorkel removal, that my MPG actually went up a bit, to between 47 & 48 with mixed riding.
 

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god i wish I really understood what you guys are talking about. this is killing me, i know there are many things I could do to my bike but I'm not good at this stuff.

oh well, i'll get my airbox removed and see if there is something I should do
 

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forchetto wrote:
4.- The fourth option is what I've done, and what this post is about. This is to remove the sensors altogether and fit blanking plugs to their bosses in the exhaust downtubes. The fuelling then reverts to whatever the main map says, in my case (map 020264) this appears to be about 13.2-13.5:1, much better for good idle and smooth low speed running. This was measured with my rather basic AFR meter. [unquote]


This is a good thread.

Decosse's point regarding the ECM trying to trim the perceived leaness sounds like it needs to be followed up on.

However I guess if the trim "saturation" limit to correct the perceived leaness was a particularly high value the bike wouldn't run or idle very well; (and the plugs would foul?) a problem you don't seem to be having.
What AFR meter are you using? AFR meters certainly appear to be useful items on these efi models. I hope to get an Innovate model eventually.

I have a yet to be deployed Tuneboy so I guess the closed loop running won't be a problem. Reading your posts about your air mods, outcomes, etc. is/has been educational.

P.S. I thought I read that the TuneECU software does not apply/won't work with Bonnevilles.
 

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Discussion Starter #11
forchetto wrote:
4.- The fourth option is what I've done, and what this post is about. This is to remove the sensors altogether and fit blanking plugs to their bosses in the exhaust downtubes. The fuelling then reverts to whatever the main map says, in my case (map 020264) this appears to be about 13.2-13.5:1, much better for good idle and smooth low speed running. This was measured with my rather basic AFR meter. [unquote]


This is a good thread.

Decosse's point regarding the ECM trying to trim the perceived leaness sounds like it needs to be followed up on.

I guess if the trim "saturation" limit was "high" the bike wouldn't run or idle very well; (and the plugs would foul?) a problem you don't seem to be having.
What AFR meter are you using? AFR meters certainly appear to be useful items on these efi models. I hope to get an Innovate model eventually.

I have a yet to be deployed Tuneboy so I guess the closed loop running won't be a problem. Reading your posts about your air mods, outcomes, etc. is/has been educational.
I kept wondering on what AFR the ECM would "settle" down to once the sensors were removed. The bike runs fine, idles well, the plugs are a nice colour and the fuel consumption appears to be normal, so I fitted the sensors back on the pipes but not connected to the bike's electrical system.

I then allowed them to heat up fully and monitored their Voltage output with a high impedance mili-voltmeter. The voltage produced can be directly related to the AFR the engine's running at.

It's showing around 0.780 volts which means an AFR of around 13.2 or so. This remains steady no matter how long it's idling, so the thing is not steadily adding more fuel, it just remains there.

This arrangement is not the ideal AFR meter, using as it does, narrowband sensors, but it has given me peace of mind.

It works fine though, and you can even see the mixture richening when you do things like placing your hand over the inlet bellmouth or playing with the IAT sensor. The change in the reading is not quite instant, takes a couple of seconds but it's interesting nevertheless.
 

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It's showing around 0.780 volts which means an AFR of around 13.2 or so. This remains steady no matter how long it's idling, so the thing is not steadily adding more fuel, it just remains there.
[unquote]

Interesting. It almost sounds like the ECM is no longer reacting (or is being overridden by another parameter or sensor?) to the lean signal otherwise it would keep trimming as per Decosse's understanding of the operation. Maybe he will have something more to add.
 

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... Interesting. It almost sounds like the ECM is no longer reacting (or is being overridden by another parameter or sensor?) to the lean signal otherwise it would keep trimming as per Decosse's understanding of the operation. .....
I suggested that it probably reaches a maximum - I don't think it goes on forever.
Recognize that Forchetto's configuration would (uncorrected) probably be even leaner than stock initially. So it might already be adding a fair positive trim even under O2 control.
i.e. it might already be using half of it's available budget under O2 control, just to get to 14.7! (Speculative!!!)
So it may well be that +/-7% fuel trim (I think that is the manual max from recollection - maybe +/-10% - I would need to be connected to see for sure) may well give that 13.2 result - it possibly just can't add any more, at least via O2 trim and that is why it settles out at 13.2 (which as 'luck' would have it, would be a good number).

What it would need would be Tuneboy to see what the fuel trim is while it's under sensor control, then again in simulated mode - you should be able to see the difference in the trim.

TuneECU is not yet ready for Bonnies as far as the MapEdit part of the program goes - however in e-mail exchange with Alain, we think the Diagnostic section may work - so currently trying that out with a Twins member of this forum

If that ends up being functional, it would be a perfect tool to check this out. And maybe even in a few months, such simulators will become unneccessary althogether if Alain finds time to work on Bonnie mapping!
 

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Discussion Starter #15 (Edited)
Further information that could be important to anyone contemplating doing this mod:

It turns out that the information that lead me to use those value resistors was in error. The value of the resistor to be used accross the O2 sensor output wires should be 1 M Ohm (1,000,000 Ohms), not 1,000 Ohms as stated.

The heater resistor remains at 330 Ohms.

I have changed it to a 1M 1 watt resistor now but the running seems to be the same as with the 1,000 Ohm one, no MIL lights with either, so I don't know what the effect of the correct value is. Will run AFR tests tomorrow and let you know.

EDIT: See post 17
 

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I suggested that it probably reaches a maximum - I don't think it goes on forever.
Recognize that Forchetto's configuration would (uncorrected) probably be even leaner than stock initially. So it might already be adding a fair positive trim even under O2 control.
i.e. it might already be using half of it's available budget under O2 control, just to get to 14.7! (Speculative!!!)
So it may well be that +/-7% fuel trim (I think that is the manual max from recollection - maybe +/-10% - I would need to be connected to see for sure) may well give that 13.2 result - it possibly just can't add any more, at least via O2 trim and that is why it settles out at 13.2 (which as 'luck' would have it, would be a good number).
What it would need would be Tuneboy to see what the fuel trim is while it's under sensor control, then again in simulated mode - you should be able to see the difference in the trim.

TuneECU is not yet ready for Bonnies as far as the MapEdit part of the program goes - however in e-mail exchange with Alain, we think the Diagnostic section may work - so currently trying that out with a Twins member of this forum

If that ends up being functional, it would be a perfect tool to check this out. And maybe even in a few months, such simulators will become unneccessary althogether if Alain finds time to work on Bonnie mapping!
Ken,
I've searched the depths of the web out of technical curiosity to find a substantive answer to this hoping for enlightenment. The best I can surmize is one of two scenarios.
There is a very consistent theme across motorcycle brands. The resistance value varies from an open circuit prevalent on virtually all Japanese EFI bikes that are by-passed successfully to 1M ohm to satisfy the ECM with always the same result. No bikes go dead rich when a resistor is used in replacement of an O2 sensor. This is peculiar however because since the theme is consistent it means the reaction of the ECM is generally the same. The KTM Superduke boys also with Keihin ECM are a bit ahead of the EFI bonnie contingent on this. They use the same dynojet O2 eliminator as all Triumph ECM's will accept with compatible O2 connector....each brand has Keihin ECM's. Many KTM owner's run these eliminators and no PowerCommander and without tuneboy map. The results are consistent...snatchiness of the transition from closed to open loop is gone with a greatly improved graduated throttle response without excessive fueling for small throttle openings with the by-pass.

The two scenario's are:
1. When a resistor is substituted the voltage drops to 0 Volts as you know. The resistor is for continuity to satisfy the internal resistance of the O2 sensor circuit within the ECM. Virtually all motorcycle brands use a 330 ohm resistor across the O2 heater leads to negate a MIL effectively replicating the heater coil by omitting it. The ECM senses this swing away from lambda and adds fuel. The bike doesn't go dead rich....just incrementally adds fuel....but the computer doesn't sense any increase in voltage as in the case with the O2 sensor present because the voltage generator aka O2 sensor is no longer in the circuit. 0.45volts or stoich is a natural centering because of the O2 sensor as it naturally fluctuates on either side of this nominal adding or subtracting fuel. With the voltage zero and unchanged, the long term fuel trim migrates and adapts toward the short term fuel trim becoming the new norm. Overtime after a number of iterations they become the same value....as it is with an O2 sensor present only with a net shift in slightly richer fueling. This change in trim is neither too rich or lean but from what I have gathered including Ernesto's report, always richer than stoich which seems to be the case with all motorcycle brands that are by-passed in this manner.

2. Scenario 1. above transpires but after a number of attempts as the long term fuel trim referred to as LTFT becomes the same with the short term fuel trim STFT, the computer defaults to open loop.
This is the most plausible scenario and seems to be the case on any motorcycle with a O2 by-pass. As you know there are air values and A/F data based upon any map for every incremental throttle and RPM position which we can play with using tuneboy or a PowerCommander and hopefully shortly with Alain's software. :) My belief when a O2 bypass is deployed, the ECM defaults quickly to open loop enlisting the fixed values in these cells for throttle position relative to RPM.

Anyway that is my best take based upon all the reading I have done to uncover this mystery. Testiment to this and no doubt you have experienced this first hand in your tuning, prior to Tuneboy offering a shut off feature to the O2 sensors, if you want either a tuneboy or Power commander program to default across the board for all running to open loop, the way to deny O2 sensor involvement is via dynojet O2 eliminators with afore mentioned resistance values. For either program and any given custom map, there typically isn't much if any fuel subtracted for low throttle openings which previously ran in closed loop...more credence to relying upon fixed air and A/F map open loop values once the O2 sensors are by-passed. I believe this to be the case for by-passing a stock Triumph ECM and mapping without any tuneboy or PC involvement as well and explains why Ernesto's bike runs so well.
Cheers.
 

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Discussion Starter #17 (Edited)
Corrections to post Nº15, further observations

Did some throrough testing today with that 1Mohm resistor in place and it's no good. There's a certain hesitation when pulling away and the pick-up from low speeds is not what it was. Took some readings with my basic AFR meter and the voltage the sensor gives is just around 0.400-0.450 V, this translates to an AFR of about 14.5-14.9 or so. Very weak for good running. I've even heard some deceleration popping today, a sure sign of a weak idle setting. This bike has never done that before.

Have found that the ECM doesn't just rely on whatever voltage comes from the sensor, but apparently it puts out 0.450 volts as a sort of bias and then reads how much the sensors output swings above and below that level to determine fuelling. Evidently the 1000 Ohm resistor pulls that voltage down a little and forces the ECM to up the fuelling, that is what I wanted really. The 1 M Ohm value is too high to put any significant load on that bias voltage.

The values of 330 and 1M Ohm are what the Dynojet eliminator has on it.

The 1 M Ohm value is OK for the Dynojet O2 eliminator because their Power Commander can then adjust the fuelling independently, but without the means to do so, like me, it doesn't give the best results. I'm going back to the 1000 Ohm :)
 

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Excellent information Ernesto and thanks for sharing your observations with us.
There is something very counterintuitive going on. In theory with the O2 disconnected from the ECM, and resistor in replacement, there is no voltage in the ECM sensor circuit. This may not be the case however. An O2 sensor is like a variable battery...more oxygen creates an ionic reaction with the membrane probe which increases EMF up to 1.0volt max. Low oxygen i.e. the ECM senses lean and no voltage. Replacing this O2 sensor/variable battery with a 1 M ohm resistor in theory should tell the ECM if anything to go more rich not leaner than a 1000 ohm resistor. This must have something to do with the architecture of the O2 sensor circuit...how it interprets lambda and how it is uses a voltage comparitor.

The good news is with 1000 ohm resistor you reported that the O2 sensor threaded into the header but disconnected creates a voltage that you correlate to an AFR of 13.2:1 or so...or perfect. :) It is difficult to fathom however that a 1M ohm resistor would not create the same condition. It is further interesting that even though the KTM bikes have a Keihin ECU, that each different brand will not work with the same level of resistor. A KTM requires a 1 M ohm resistor and you have taught us that our bikes need a 1000 ohm resistor for best down low fueling. Your observation about why the dynojet O2 eliminators work with PC and measure 1M ohms is spot on I believe.
Thanks again.
 

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Discussion Starter #19
I realise that all this messing about could be done away with if I installed a proper oxygen sensor simulator circuit as shown on post 6 but somehow I prefer the simplicity and robustness of this simple mod.

On lots of other systems for other bikes and cars, you only have one O2 sensor to deal with, therefore just one simulator needed. With our bikes you need two and then the problem of adjusting them independently arises. Could be a nightmare.
 

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Yes we could build an O2 simulator with amplified circuit for $20 per side as you know. But...there are tons of sport bikes running around without fuel controller or tuneboy with either an open circuit where the O2 sensor used to reside or a resistor in place and fueling down low is fine. What is very interesting is there doesn't seem to be a complete default to open loop A/F and air map cell values based upon your comparison testing. The resistor seems to affect fuel trim which becomes a steady state AFR which is sensitive to resistance value. If you become particularly adventuresome, it would be informative to know what AFR would result from say a 500 ohm resistor....or perhaps a 5,000 ohm resistor and chart AFR accordingly. If you have other resistors available and your O2 sensors still screwed in for measurement (disconnected from the ECM) with a multimeter...it would be interesting to see what the associated voltage and AFR is.
Perhaps there is a better resistance value that will create fueling closer to 13:1 although ~13.2:1 is darn good. :)
Cheers.
 
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