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Discussion Starter · #23 ·
Thanks guys! I plan to flash the ECU, maybe next season. I want to put back the Yoshimura, even if it is a pain in the ass to install or remove (it is too tight). If the culprit is the Yoshi, I have to flash anyway. I will see if I can find a place near me that flashes the ECU.

I have a question about the O2 sensor: if I remove it, wouldn't it adversely affect how the bike adapts to elevation changes?
 

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. . .
I have a question about the O2 sensor: if I remove it, wouldn't it adversely affect how the bike adapts to elevation changes?
No. Elevation changes (i.e. atmospheric pressure changes) are compensated by a dedicated sensor elsewhere in the EFI system. The O2 sensor ONLY affects AFR.

Jim G
 

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Thanks guys! I plan to flash the ECU, maybe next season. I want to put back the Yoshimura, even if it is a pain in the ass to install or remove (it is too tight). If the culprit is the Yoshi, I have to flash anyway. I will see if I can find a place near me that flashes the ECU.

I have a question about the O2 sensor: if I remove it, wouldn't it adversely affect how the bike adapts to elevation changes?
No. Elevation changes (i.e. atmospheric pressure changes) are compensated by a dedicated sensor elsewhere in the EFI system. The O2 sensor ONLY affects AFR.

Jim G
Yes it does. Higher elevation means less oxygen in the air. Hence why you lose a bit of power as you go up in elevation. Granted unless you're changing elevation drastically in your ride it's not going to be noticeable. If you're out in the Rockies and you live at the base of the mountains and decide to ride up Pikes Peak, then it will affect how your engine runs, but if you're just going up or down a few hundred feet it's not going to be noticeable.
 

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Thanks guys! I plan to flash the ECU, maybe next season. I want to put back the Yoshimura, even if it is a pain in the ass to install or remove (it is too tight). If the culprit is the Yoshi, I have to flash anyway. I will see if I can find a place near me that flashes the ECU.

I have a question about the O2 sensor: if I remove it, wouldn't it adversely affect how the bike adapts to elevation changes?
If it's a PITA to remove, and you already plan on getting an ECU flash, why not just do it now rather than go through the troubles with the exhaust and your O2 sensor? It's not an expensive or difficult mod. Send it in to Norton. He has the best "mail-in" flash for these bikes as far as I've seen.
 

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Clarification after sbk1198's posting. While thinner air affects the power that an engine produces at higher elevations, the O2 sensor specifically does nothing to affect that. The O2 sensor simply sends a rough indication of current AFR to the ECU, so that the eCU can try to maintain AFR a bit on the lean side. It does not make the high altitude power performance of the engine better or worse.

Jim G
 

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Clarification after sbk1198's posting. While thinner air affects the power that an engine produces at higher elevations, the O2 sensor specifically does nothing to affect that. The O2 sensor simply sends a rough indication of current AFR to the ECU, so that the eCU can try to maintain AFR a bit on the lean side. It does not make the high altitude power performance of the engine better or worse.

Jim G
And when you remove the O2 sensor and the ECU is not getting that reading anymore? The ECU is programmed to inject more fuel throughout the whole range and the AFR becomes richer, but it does so at a set rate. Now when you go up at higher elevations it's still injecting that same amount of fuel because it doesn't know any better, but the engine is getting less air, so now it's running even richer. So yes, removing the O2 sensor DOES affect the way the bike runs at higher elevation. But is it really bad and noticeable? Not really unless you go really high up in elevation.
 

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And when you remove the O2 sensor and the ECU is not getting that reading anymore? The ECU is programmed to inject more fuel throughout the whole range and the AFR becomes richer, but it does so at a set rate. Now when you go up at higher elevations it's still injecting that same amount of fuel because it doesn't know any better, but the engine is getting less air, so now it's running even richer. So yes, removing the O2 sensor DOES affect the way the bike runs at higher elevation. But is it really bad and noticeable? Not really unless you go really high up in elevation.
No. That’s incorrect. The O2 system has nothing to do with the corrections made for temp and altitude. That all functions exactly the same after a flash. The tuning changes only apply to the base map.
 

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No. That’s incorrect. The O2 system has nothing to do with the corrections made for temp and altitude. That all functions exactly the same after a flash. The tuning changes only apply to the base map.
Does the stock narrowband O2 function differently than wideband O2 sensors? I guess I've never used the stock ones before, but with a wideband O2 sensor in, that's exactly what happens. I did it on the dyno last weekend cuz I was curious what happens when you turn it off. What purpose does the stock O2 sensor serve then if not to send the ECU info about AFR so that it can adjust the fuel??
 

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The stock O2 sensor does as you said. But only in its small range. But there still has to be corrections made for changing conditions. If it didn’t the bike couldn’t handle running well on a cold 50 degree morning and then a hot 90 degree afternoon. Remember the O2 system makes changes very slowly over time.

I’ve never used wide band in a direct feedback control system. Only for monitoring. But I don’t think there would be any difference.

I’d like to hear more about what you saw on the dyno.
 

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The stock O2 sensor does as you said. But only in its small range. But there still has to be corrections made for changing conditions. If it didn’t the bike couldn’t handle running well on a cold 50 degree morning and then a hot 90 degree afternoon. Remember the O2 system makes changes very slowly over time.

I’ve never used wide band in a direct feedback control system. Only for monitoring. But I don’t think there would be any difference.

I’d like to hear more about what you saw on the dyno.
My wideband O2 sensor used to be on all the time in a closed loop control system along with the aRacer ECU, up until last weekend when I did a full custom tune by individual cylinder and now I have it turned off. But before I started tuning it, I got some baselines with the wideband sensor on and off because I was curious what the difference is. I apologize, I remembered it the opposite it seems, it actually goes leaner when disabling it for most of the range. Goes richer in the low range, and stays about the same at the top end, but from 5500 to almost 11,000 it gets leaner. Green line is with the sensor disabled, no other change between the runs other than that. Top graph is cylinder 1 AFR, bottom is cylinder 2 AFR.

Although maybe this doesn't translate the same way to a stock bike. After all this isn't the stock ECU, and most likely it's programmed quite differently than the stock one. Additionally, since I have bored throttle bodies and a different intake, it would make sense that more air goes in than if it was stock, and without the wideband O2 sensor to tell the ECU that it's running lean, it doesn't know to inject more fuel in. I guess I would have to do this test with a more stock bike and stock ECU, but it makes sense to me that the O2 sensor would have an impact on running behavior without flashing the ECU. Otherwise why would they put it on? You said the stock sensor has a small range that it works in. What is that range and how does that compare to a wideband O2 sensor range?

20180
 

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It’s really great that you can now do this stuff.

I have no experience with aRacer so you’re becoming the expert on that. But since it can function without the wide band controller that tells me it functions similar to any ECU. You flash a base map created under some set condition. Your wide band controller makes tuning changes in real time to try and maintain your target AFR. When you disconnect the O2 sensor it should default back to your base map.

When the O2 is disconnected it still needs to be able to make corrections for temp and pressure or it would run terrible anywhere but your dyno room and whatever temp it was when you built the base map.

The wide band controller works at all throttle opening and any rpm. The stock system only works and small throttle openings and low revs. I’m not sure exactly what those setting are but normally below 6k revs.
 

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Just another clarification: As I stated in my recent lengthy posting about using an O2 Sensor Eliminator, the cheap "narrow band" OEM O2 sensor is WAY more primitive than a proper costly wideband O2 sensor. It's more like a "switch" than a real sensor. A wideband sensor can actually trigger useful AFR adjustments if connected to the right sort of ECU or piggyback device that has been set up to accept a wideband signal, but a narrowband sensor is useless and detrimental for that role.

I've permaently repalced my OEM O2 Sensor with Kawasaki Brad's O2 Sensor Eliminator, which has given me an extra 2.5% richer AFR than OEM. (As explained in that O2 Sensor Eliminator posting).

Jim G
 

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It’s really great that you can now do this stuff.

I have no experience with aRacer so you’re becoming the expert on that. But since it can function without the wide band controller that tells me it functions similar to any ECU. You flash a base map created under some set condition. Your wide band controller makes tuning changes in real time to try and maintain your target AFR. When you disconnect the O2 sensor it should default back to your base map.

When the O2 is disconnected it still needs to be able to make corrections for temp and pressure or it would run terrible anywhere but your dyno room and whatever temp it was when you built the base map.
Right, agreed. And yeah it makes sense that it should default to its base map. I just remembered why I was thinking before that it became much richer when I turned it off. I got my memory confused with a different bike, because before I did all that on my 400, I was at the dyno with a new Grom to tune that, also with an aRacer ECU and an autotune/wideband module. It was on that bike that it got significantly richer after I turned the wideband sensor off (like dropped to about 11-11.5 AFR in a lot of the range). I don't have that on my computer though to look at again, probably still on the dyno laptop. No idea what map was loaded onto that ECU though because it wasn't new, it was borrowed from someone else who used it on his Grom.

The wide band controller works at all throttle opening and any rpm. The stock system only works and small throttle openings and low revs. I’m not sure exactly what those setting are but normally below 6k revs.
Ah I see. I suppose that's why it's called a narrow-band lol

I just bought an overpriced can of fuel (MR12) today, so tomorrow I'm gonna go map a fuel map for my 400 with that and see the gains. I always heard from others that about 2hp is about average, so I'll see. I'm curious how it will do over the whole range, although since I'm only going to use MR12 at Daytona I'm more interested in what happens at the top end.
 

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Right, agreed. And yeah it makes sense that it should default to its base map. I just remembered why I was thinking before that it became much richer when I turned it off. I got my memory confused with a different bike, because before I did all that on my 400, I was at the dyno with a new Grom to tune that, also with an aRacer ECU and an autotune/wideband module. It was on that bike that it got significantly richer after I turned the wideband sensor off (like dropped to about 11-11.5 AFR in a lot of the range). I don't have that on my computer though to look at again, probably still on the dyno laptop. No idea what map was loaded onto that ECU though because it wasn't new, it was borrowed from someone else who used it on his Grom.



Ah I see. I suppose that's why it's called a narrow-band lol

I just bought an overpriced can of fuel (MR12) today, so tomorrow I'm gonna go map a fuel map for my 400 with that and see the gains. I always heard from others that about 2hp is about average, so I'll see. I'm curious how it will do over the whole range, although since I'm only going to use MR12 at Daytona I'm more interested in what happens at the top end.
MR12 is about as radical as it gets. I tried it once but with the on bike auto tune I could only tune for a guessed at afr. I shot for 12.8 and it ran really well but I have no idea what afr it really needs or produces the most hp. I would love to hear what afr you end up with on the dyno. I’ve also heard it likes a lot of timing advance but don’t know if that’s true or not.
 

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MR12 is about as radical as it gets. I tried it once but with the on bike auto tune I could only tune for a guessed at afr. I shot for 12.8 and it ran really well but I have no idea what afr it really needs or produces the most hp. I would love to hear what afr you end up with on the dyno. I’ve also heard it likes a lot of timing advance but don’t know if that’s true or not.
I'll let you know in a few hours. I'm heading there now. I've actually heard MR12 likes retarding the timing by 1 or 2 degrees...at least that's what Norton told me earlier this year when I ran it at Daytona. I'm going to try going +2 and also -2 from where I'm at now and see how much difference that makes.
 

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Discussion Starter · #39 ·
So update: I got another O2 sensor error (33) even after swapping the exhaust. It went away today so it seems intermittent. I am due soon to have my 18 000 km maintenance done so I will tell the dealer about this issue. In general, I tend to leave all my options open, unless I learn more about the issue. While the mountains here are not very high, I would like one day to make trip to the Rockies on the motorcycle so for now I plan to keep the sensor. Or maybe replace it with a wideband if I flash the ECU anyway? I will look more into this issue. If anyone has some info that I can read about 02 sensors, I would appreciate the contribution to my education.

For now, I will keep the Kemimoto unless I really want to do a 30 minute workout, in which case I will put back the Yoshi. Maybe some ACF50 or some oil will help with that issue.

If it's a PITA to remove, and you already plan on getting an ECU flash, why not just do it now rather than go through the troubles with the exhaust and your O2 sensor? It's not an expensive or difficult mod. Send it in to Norton. He has the best "mail-in" flash for these bikes as far as I've seen.
About the flash, I have to save some money first AND I don't want to have the bike out of action for a few weeks. I plan to do this either in the off season, while the bike is in my inlaws garage, or next season get the Norton flash with the ECU swap option. Or maybe find someone close that can do it (I have asked the dealer about it, they were supposed to get back to me with more info about who can flash ECUs around here).
 

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So update: I got another O2 sensor error (33) even after swapping the exhaust. It went away today so it seems intermittent. I am due soon to have my 18 000 km maintenance done so I will tell the dealer about this issue. In general, I tend to leave all my options open, unless I learn more about the issue. While the mountains here are not very high, I would like one day to make trip to the Rockies on the motorcycle so for now I plan to keep the sensor. Or maybe replace it with a wideband if I flash the ECU anyway? I will look more into this issue. If anyone has some info that I can read about 02 sensors, I would appreciate the contribution to my education.

For now, I will keep the Kemimoto unless I really want to do a 30 minute workout, in which case I will put back the Yoshi. Maybe some ACF50 or some oil will help with that issue.



About the flash, I have to save some money first AND I don't want to have the bike out of action for a few weeks. I plan to do this either in the off season, while the bike is in my inlaws garage, or next season get the Norton flash with the ECU swap option. Or maybe find someone close that can do it (I have asked the dealer about it, they were supposed to get back to me with more info about who can flash ECUs around here).
Teorist: Just so you know, you do NOT simply "substitute" a wideband sensor for a narrowband sensor. A wideband sensor can only work with an ECU or piggyback device that is designed to work with a wideband sensor. Such setups are VERY costly, AND your local dealer will no longer be able to do any troubleshooting or repairs due to EFI issues. So research this very carefully before you buy one or more components of a wideband-capable solution and then find that you either can't afford the entire solution or don't want it because you then would have to do all your own EFI and trouble code troubleshooting.

I've nade multiple cross country "Rocky Mountain" trips in my lifetime, and even a 9300 mile circumnavigation of the USA, with my wife and only 15 lb of luggage and a great 35mm camera on the bike. I can tell you with great emphasis, such trips are best made with motorcycles that a local motorcycle dealer of ANY brand can help you troubleshoot any issues that might arise.

Jim G
 
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