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JA50N

Stock ECU

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JA50N
Does the stock ECU read the O2 sensor at WOT?  If not, at what point does the system switch from closed loop to open loop?  If it does not read the O2 at WOT, how are these companies that are making exhaust systems saying they do not need a fueling modifier?  I have a pretty extensive experience in tuning EFI cars but not bikes.  Trying to get knowledgeable on the way these things are done.
 
Jason

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hypnotik
The o2 sensor only provides feedback to the ecu during closed loop. Under WOT the ecu goes to open loop and runs on a preset map according to RPM. Cars are usually speed density or mass air, bikes are generally only Alpha N. They only read RPM and throttle position. From the factory the fuel map isn't on the ragged edge of destruction so an aftermarket exhaust doesn't provide enough extra airflow through the motor to make an unsafe condition using the factory fuel map. But, with a fuel controller the AFR's can be optimized to make a bit more power.
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JA50N
So i know the bike has a coolant temp sensor, i'm guessing it also has a inlet air temp sensor also?

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hypnotik
Probably but I don't know 100%.

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Guest Ralph
Yep it uses the same one they use for the air temp on the display
that's why it is a bit out under certain conditions as it's really
a intake air temp reading.
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jbird
 

The o2 sensor only provides feedback to the ecu during closed loop. Under WOT the ecu goes to open loop and runs on a preset map according to RPM. Cars are usually speed density or mass air, bikes are generally only Alpha N. They only read RPM and throttle position. From the factory the fuel map isn't on the ragged edge of destruction so an aftermarket exhaust doesn't provide enough extra airflow through the motor to make an unsafe condition using the factory fuel map. But, with a fuel controller the AFR's can be optimized to make a bit more power.
 
So is it nessisarry to purchase a dobeck fuel manager after AM exsaust install, these things are roughly 250 dollars, do I risk damage to the engine if I don't get one, and run the exsaust as is out of box

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fzhooligan
I ran mine without a tuner for like a month before I installed the controller. I put about 20 miles a day, it just pops a bit on decel.
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'15 FZ-07
'93 Honda XR650L (supermoto/pig) (SOLD)

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jbird
 

I ran mine without a tuner for like a month before I installed the controller. I put about 20 miles a day, it just pops a bit on decel.
Did you have any engine problems, or other concerns beside the decel popping ?

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fzhooligan

I ran mine without a tuner for like a month before I installed the controller. I put about 20 miles a day, it just pops a bit on decel.
Did you have any engine problems, or other concerns beside the decel popping ?
not at all

'15 FZ-07
'93 Honda XR650L (supermoto/pig) (SOLD)

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hypnotik
I've had my exhaust on with no fuel controller for almost 2k miles, no issues.

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gremlin
So to help clarify some things, let's (s)talk ECU.
 
***This is clearly for better understanding and speculation.
 
Does anyone know when the closed loop stops?
 
At what throttle position and/or rpm does the open loop kick in?
 
For instance:
let's say hypothetically that closed loop is based on throttle position.
Let's use arbitrary numbers, ( unless someone actually knows the real stock
Positions. Say: closed loop is 0% - 60% TP. Then 60%- 100% is open loop.
Yamaha did a pretty decent job with fuel mapping for stock setup considering
Emission standards and what not ( we don't need to get into that now)
Or.....
It's load based: meaning at a given RPM. Maybe just under 4k Rpms at a specific throttle position. Like; like cruising. That the closed loop is in.
Idle, 2,000rpms- 4,000rpms at 0%- 30% throttle position.
 
Now, I know lots have removed the stock 02 sensor after adding fuel controllers. From my understanding as well as Dillons at Dobeck and Nels and Pat at 2 WheelDynoWorks that it goes into safe mode and richens up the closed loop section. We think, unless someone knows for sure that it brings in
And around 13.2-13.5:1 AFR. With NO CEL that comes on. Again Yamaha did a decent job having this just for EPA or whatever regulations...we know from various tuners that the stock ECU fuel mapping is lean on bottom and richer on top, but still more on the lean side of things.
 
Now, since disconnecting the 02 sensor richens up the closed loop section and/or goes into safe mode.
 
Is it safe to say that just disconnecting the 02 with any after market exhaust be just right in the fuel targets?! Now, I know there's certain variables that play a big roll in tuning: rider weight; altitude; humidity ect. Ect....
 
What I'm getting at is...those that have anafter market exhaust ( doesn't matter what brand) and are running a fuel controller and/or an ECU reflash
Have better results removing the 02 sensor?!
 
I have an akrapovic Ti baffle is removed and have an ECU flash. I did and still kinda am doing some R&D. Testing different variation of performance. Basically my bike is running pretty damn good with an ECU flash AND with my 02 sensor disconnected. I'm gonna try adding in the baffle in, then connecting the 02 sensor then disconnecting, then running it with Cat and baffle 02 connect and then disconnected to see is there's any performance
Differences.
 
I know those of us running the Akrapovic without baffle are mostly likely suffering from a thing called Reversion ( Dillion at Dobeck helped shed some light on this also) that possibly its robbing us from its full potential due to not getting accurate readings from (a) stock 02 sensor (b) stock ECU closed loop or both....anyways that's my rant and understanding those far and hope other will chime in on this as I'm only doing this to understand it better.
 
I'm not here to argue Dyno numbers or graphs cause that's a whole other topic and plus Dyno's aren't always accurate and best at creating targets.
(So much comes into that)
 
Anyways.......your turn :)
 
 
 
 

Honda Grom
CB 350

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norcal616
My knowledge of when the o2 sensor is disabled for aftermarket exhaust with/without a tuner/reflash it let's the built in preset fuel tabs for " safe mode" kick in for a very stable fuel tab to tune off of...or to use to the fuel tabs that are constantly tweaking due to a connected o2 sensor to tuNE off of... I also know most 02 sensors are set for a certain EPA friendly AFR range from factory unless u buy specialty o2 sensors that are made for tuning...

2015 fz-07- Hordpower Edition...2015 fj-09- 120whp- Graves Exhaust w/Woolich Race Kit- tuned by 2WDW
 

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Guest Ralph
I noticed the ECO thing switching on and off the other day and did wonder
if it switched with the system going open and closed loop.

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gregjet
Just a little point. The bike does have a air temp sensor and there is a little trick that will help you richen up the mix a little for almost free.
The sensor is at the front of the tank under the tank shroud and in a pocket of what becomes hot air . It is a single bolt on. You can move it to behind the air mesh scoop on the right side and it will get cooler air. This should tell the ECU it needs a richer mix.
Haven't seen the PCV wiring for this bike, but on a few of them, has a wire from the ECU that goes to the "O2" sensor attached to the PCV to fool the ECU into thinking it is getting a perfect signal. ( MY BMWF800R had one). The sensor is then disconnected.
That is why a reflash is a better option on a lot of bikes as the ECU will still use the "O2" sensor to get the AFR right according to the NEW tables which will be a better mix.

Go forth and modify my son...go forth and modify...

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gremlin
This is interesting, cause I have an ECU flash an although it ran good with the 02 connected, it runs better with my 02 disconnected. Will see when I go up to the canyons at 3,000ft.
 
Has anyone ran the Akrapovic Ti with cat and baffle with the stock ECU setup? Or with an ECU flash?
Wondering the power difference, if any?!

Honda Grom
CB 350

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gregjet
Usually the "O2" sensor takes a while to adjust. It isn't usually instant. It is possible the reflash was done for the sensor disconnected?

Go forth and modify my son...go forth and modify...

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gremlin
Usually the "O2" sensor takes a while to adjust. It isn't usually instant. It is possible the reflash was done for the sensor disconnected?
 
 
I believe your correct. Nels was stating they test with 02 disconnected. Cant imagine it taking to long for it to adjust, right? What like 5-10miles?

Honda Grom
CB 350

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gregjet
Not sure. They are an "expert" system. They adapt over a weighted average so takes a while. The BMW one can take a few weeks to completely set new tables.

Go forth and modify my son...go forth and modify...

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wickedtwister
When I was talking to nels at 2wdw he said that the stock o2 sensor is only read at 5% or under engine load. So basically when the eco light is on in the display. A tune from flash or add on fuel controller is needed to correct the fueling the other 95% of the engine load. Most engines use maps sensor settings to determine engine loading at a given RPM. If you do a exhaust I'd highly recommend a flash to correct fueling of some sort.

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JA50N
Our bike has no MAP sensor. It determines engine load from throttle position, RPM, and possibly speed. If you watch the ECO light it really is only lit during steady throttle input at a constant speed. Not very often. If it is anything like a OBD2 car system, the O2 sensor only adjusts fuel trims during steady state when the system is in closed loop (indicated by the ECO light). Narrow band O2 sensors are also only accurate in a narrow band around 14.7:1 AFR so the only time they are used is when that is the target AFR.

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enels57
I think this all feeds into my question of bike performance at different temperatures....not just ambient temp but the temp the bike sensor is seeing.
 
What got my attention was on a cool morning last week I gave the throttle a little twist at 4k rpm and the front came up effortlessly.  There had been little traffic and the temp indicator was reading pretty close to the actual temperature...about 62 or so.
 
So on the way home I thought I would try to replicate the experience...only this time the ambient temp was about 90, BUT because of moving through slow traffic and having a tailwind the temp indicator was reading more like 105. Totally different result...the front felt like a brick compared to the earlier result.  I thought there was more to this than just the 25 degrees air temp difference.
 
Sidebar: I have actually sat at a long red light here in AZ this summer and had the temp indicator reading 139 degrees...not the engine temp indicator, the air temp indicator. Youch.   The bike was running pretty doggy and I was too.  
 
It's great to learn more about this bike...plenty more to learn. Thanks

"Look into it later when the dust is clearing off the crater" - Iggy Pop

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gregjet
The position of the air temp sensor means it gets the hot air from the radiator. I moved mine out to behind the right side mesh on the tank cover. Helps riched the AFR as well ( a bit).
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Go forth and modify my son...go forth and modify...

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