NB sensor over 85 Kpa

[ultraswede]

I see a lot of comments that NB wont read above 85 Kpa.
Surly that must be totally incorrect?

Like, how on earth would the NB sensor know the Map, or care for that matter?
My take on this, is that the ECU don't use data gathered over 85 Kpa.

Whats 60 kpa in one motor, might be 100 kpa in a different motor, exhaust volume and temp vise.

A side note, on cars its possible to read NBs, and tune all the way to above 100 Kpa.

[Jamie Long]

I see a lot of comments that NB wont read above 85 Kpa.
Surly that must be totally incorrect?

Like, how on earth would the NB sensor know the Map, or care for that matter?
My take on this, is that the ECU don't use data gathered over 85 Kpa.

Whats 60 kpa in one motor, might be 100 kpa in a different motor, exhaust volume and temp vise.

A side note, on cars its possible to read NBs, and tune all the way to above 100 Kpa.

It is not an issue with the nb O2 sensor itself as it will certainly read above 85Kpa, very accurately if it is at or very near stoich   

[ultraswede]

 Thanks for the clarification

[rbabos]

I see a lot of comments that NB wont read above 85 Kpa.
Surly that must be totally incorrect?

Like, how on earth would the NB sensor know the Map, or care for that matter?
My take on this, is that the ECU don't use data gathered over 85 Kpa.

Whats 60 kpa in one motor, might be 100 kpa in a different motor, exhaust volume and temp vise.

A side note, on cars its possible to read NBs, and tune all the way to above 100 Kpa.

It is not an issue with the nb O2 sensor itself as it will certainly read above 85Kpa, very accurately if it is at or very near stoich

My understanding is it will read acurately all the way up if it's kept at stoich. By 80kpa they are forced to go open loop, out of stoich and are not reliable in that state. That about right?
Ron

[joe_lyons]

I tuned with my PV out on the road with stock O2 sensors and 100% throttle was spot on 13 but I think for the majority of people it is not advised to do so but I go against the grain.

[rbabos]

I tuned with my PV out on the road with stock O2 sensors and 100% throttle was spot on 13 but I think for the majority of people it is not advised to do so but I go against the grain.

Did you physically set the upper kpa to stoich or ran it as the map was to get this result?
Ron

[joe_lyons]

Just done basic "autoadjust" and if I remember I set the max kpa to above 100. I put the bike in 6th gear to get the lower rpms at a slower rate and when I got to about 70 I bring it back down and go to 5th and do my mid and upper rpm and use the brakes for short periods to slow things down a bit.  Always could see temp. Throttle% and knock f&r.  BUT as it is my bike is a stock motor with pipes and heavy breather so my motor is far from the edge so would prob. not suggested for built motors that are closer to the edge.

[1FSTRK]

I tuned with my PV out on the road with stock O2 sensors and 100% throttle was spot on 13 but I think for the majority of people it is not advised to do so but I go against the grain.

I have no experience with PV so please bare with me but how did you determine that 100% throttle was at exactly 13? Don't the NB sensors only give feedback from about 14-15?

[joe_lyons]

When you go into basic mode it sets the whole afr table to 14.6 and then sets the clb to a bit richer that 14.6 like 14.4 I think.  Then the ecm does what it can within its limits to achieve that ratio. Does it get hot quicker than tuning at 13.0 ya, but you gotta keep an eye on things. If the ecm can get the VE correct to get 14.4 then it knows what to do to get the afr to a requested 13.

[wurk_truk]

and did you check the AFR with an off board wego/checker/gauge?

[1FSTRK]

When you go into basic mode it sets the whole afr table to 14.6 and then sets the clb to a bit richer that 14.6 like 14.4 I think.  Then the ecm does what it can within its limits to achieve that ratio. Does it get hot quicker than tuning at 13.0 ya, but you gotta keep an eye on things. If the ecm can get the VE correct to get 14.4 then it knows what to do to get the afr to a requested 13.

Thanks, With the TTS it is not even an option so that is why I asked. The guy that does my final tune with a dyno uses EGT for 80 and 100%, he leans to peak power and then adds fuel until the EGT is at a safe level as needed. Just curious how did you determine that 13:1 AFR makes best power?

[ultraswede]

By 80kpa they are forced to go open loop, out of stoich

Wonder why?

Cars don't do this.....

[ToBeFrank]

By 80kpa they are forced to go open loop, out of stoich

Wonder why?

It is a limitation of the ECM and control system itself, at or near WOT it simply cannot lock down closed loop, roll the integrator, allow the sensors to switch, and essentially do business as usual. In most cases I recommend if you are using the factory O2 sensors limiting the closed loop range to 70-80Kpa, beyond that there are obvious limitations from both running the bike at stoich, how the system responds, and the data coming back.

This makes sense, except I would think it would be more related to RPM than MAP.

[joe_lyons]

and did you check the AFR with an off board wego/checker/gauge?

Found some time to throw it on the dyno and ram the sniffer up her.

[hrdtail78]

A couple of system will allow you to collect data and map VE's at 100kpa with the NB's.  I have collected data with SESPT and then sniffed with BB's.  Different target AFR.  The bike was 14+ lean.  Automaticly gianed power and smoothed out curve targeting 13.  Keep in mind I have only done this with one bike, one time.  So, If I ever do it again.  It might not be the same.

[rbabos]

When you go into basic mode it sets the whole afr table to 14.6 and then sets the clb to a bit richer that 14.6 like 14.4 I think.  Then the ecm does what it can within its limits to achieve that ratio. Does it get hot quicker than tuning at 13.0 ya, but you gotta keep an eye on things. If the ecm can get the VE correct to get 14.4 then it knows what to do to get the afr to a requested 13.

Interesting. I was aware of the clb change for autotuning but not about the whole cal reset to go closed. Not visible if one chooses BASIC mode and it does it automatically. With TTS it was seen to not close loop the upper kpa area, hense the issue with NBs in this area of operation.
Ron
Ron

[ultraswede]

If the ecm can get the VE correct to get 14.4 then it knows what to do to get the afr to a requested 13.

Exactly. This is how I am used to tune Gen III V8s

It should be possible (for the tuning product engineer) to provide a software switch that prevent the ECM to turn CL off at 80-85 Kpa.
If that was done, we could V-tune all the way up to WOT.

(If I melt my motor, it would be my fault, as it is today if I damage anything with my tuning)

[wurk_truk]

(If I melt my motor, it would be my fault, as it is today if I damage anything with my tuning)

From Talking to Steve at the show, this is THE very reason we do not see this capability on VTune.  One would really need to check the data out forwards and backwards, mentally, before accepting the tune.  Problem would be an outlier COULD damage the engine and it WOULD take a careful review.  His feeling, from doing this awhile, is that not everyone would be careful and the product simply HAS to be designed for the 'lowest common denominator' kind of customer.  Look at ALL the warnings about MTEs, and even I didn't follow that fully on the rat bike.

[ultraswede]

WURK_TRUCK,
Yes i see your point.

BUT being able to tune 85-100 Kpa in CL/V-tune would be harmless,
compared to how one can FUBAR his engine as the tuners function today!
(not complaining, just stating facts.)

It would also lay to rest a whole shipload of mud that's been flying around over this "feature".

[1FSTRK]

(If I melt my motor, it would be my fault, as it is today if I damage anything with my tuning)

From Talking to Steve at the show, this is THE very reason we do not see this capability on VTune.  One would really need to check the data out forwards and backwards, mentally, before accepting the tune.  Problem would be an outlier COULD damage the engine and it WOULD take a careful review.  His feeling, from doing this awhile, is that not everyone would be careful and the product simply HAS to be designed for the 'lowest common denominator' kind of customer.  Look at ALL the warnings about MTEs, and even I didn't follow that fully on the rat bike.

I have to call BS on this one. It did not and does not stop Steve from selling units to  anyone with a pre o2 sensor bike where they can put in any ve number or AFR they dream up.   

[Jamie Long]

It should be possible (for the tuning product engineer) to provide a software switch that prevent the ECM to turn CL off at 80-85 Kpa.
If that was done, we could V-tune all the way up to WOT.

(If I melt my motor, it would be my fault, as it is today if I damage anything with my tuning)

It's already in there, the target Lambda/AFR is the switch. On cable bikes 14.6 is the closed loop switch, anything other than 14.6 turns off closed loop. On Lambda calibrations the ECM uses a specific Closed Loop Lambda table, on most cals it is in the range of .97-1.01, request a target outside these values and it is not closed loop. Power Vision has this table exposed and editable in WinPv, you can also use the factory sensors to populate correction data above 80Kpa. However this requires the AFR/Lambda set to stoich, not something we generally recommend in the tuning world.

Also note, if we are using the factory sensors for corrections we are not looking at O2 sensor output specifically, we are relying on O2 integrator/AFF correction data from the ECM doing business as normal that it has already populated, these corrections are then applied back into the base tune. A stoich mixture above 80Kpa is not generally normal operation, nor is it an optimum state for data collection with a non linear O2 sensor.

[ultraswede]

nor is it an optimum state for data collection with a non linear O2 sensor.

What would the NB sensor know about MAP, or for that matter care about MAP?

[Jamie Long]

nor is it an optimum state for data collection with a non linear O2 sensor.

What would the NB sensor know about MAP, or for that matter care about MAP?

The nb O2 sensor does not know or care whether map is 20Kpa or 100Kpa. Consider though for a moment what we are asking from the ECM, we are are requesting it to control the mixture at stoich at a high load, using a sensor which is non linear with a relatively small window to work with in the first place, not even considering how the ECM handles the ST/LT fuel adjustment which corrections are based of in the first place. This "less than optimum" state brings up a wide range of questions in itself, the first & foremost: assuming one is developing the tune because the calibration is not correct in the first place (thats why you are tuning it right?) lets say for example the motor happens to be lean at WOT assuming the base map has a "normal" Lambda/AF target of say 13.0 AF, what happens when you set the calibration to force closed loop @ stoich 14.6 AF so you can use the factory O2 sensors and run thru WOT to populate your corrections? ......there is a very good chance your already incorrect calibration will be running the motor @ 16.0:1 AF or even leaner, not to mention doing this under load at full throttle. That should answer alot of questions on this subject.

Trust me I am a big fan of tuning with O2 sensors both narrow and wideband, and they both work excellent for their intended purpose especially when used within their limitations. However having tuned several thousand motorcycles over the past 15 years I would absolutely never tune high load area's or WOT @ stoich regardless of which sensor was being utilized.   

[joe_lyons]

I would like to say that I don't endorse tuning high load with narrow bands but this is my personal bike and I also tune bike for a living on a dyno.  The fact that I had to break a few laws to achieve these rpm ranges was prob. dumb and should not be copied.  The main thing is, is that you could/can tune those areas with NB but the issues or danger that you could run into could be great.  The best overall tune is still done by a professional on a dyno.

[ultraswede]

The best overall tune is still done by a professional on a dyno.

The key word being professional, very few I would trust to know more about engine combustion theory than I do myself. 

Back to the subject of the thread,
The notion that Map is what determine the load of an unknown engine combo, I don't buy that.

A stage 1 96" will have a thermal load similar to say a 124" stage 4 at 40 Kpa.(example)
To tune the 124" with CL is fine at 50 Kpa, but the 96" at 86 Kpa is not..........

I understand that this is programed in to the ECM (jumping out of CL @ 85 Kpa) so I don't criticize any tuning product.

But is sure would be nice to be able to do this, if I chose to do so.
As been said before, ignition and VE tables is potentally more dangerous to the engine than tuning i CL @ 85 Kpa +.