CLB setting vs lambda setting

[07heri]

Guys, a while back we had a good discussion on CLB settings while making tune runs.  The lambda maps don't have the CLB bias table.  So I'm curious how this relates to lambda.  Is there a centered point setting that keeps the NB sensors in a more effective zone?  I see allot of posts saying set it .98.  Is this on the richest side of the slope, if comparing it to a CLB setting? Why use .98 versus ,985, .990, .995?  And why?  I know .98 will be a little richer and still in closed loop, but what setting would make the sensor happier?

Thanks

[razorsedge]

Your question is similar to one that I asked a week ago or so.  When setting up you VTune map the TTS guide says to use 0.981 Lambda.  You can set the table at this constant except in the 90kpa and above range, that range is not adjustable.  I certainly understand TTS thinking by locking that kpa area,  besides on the street it will most difficult to hold the bike at that kpa and correct RPM range to fill the cells.  Just a side note...I understand why you have to sign the dyno tune agreement before the tuners starts working on your bike.  The engine is not undergoing the most favorable operating conditions to get it tuned.  To say the least, I think the engine is definitely being stressed and so is the rear tire.  Has anyone taken an infrared heat measurement of the rear tire during  dyno tuning?

[07heri]

Yes I see .981 tossed around allot.  But my question is why .981?  Back when we had CLB tables it wasn't recommended to set the CLB too high as it limited the swing or effective range on the high side.  I'm curious if this same principle applies to the lambda setting.  Basically, without considering rich or lean, where is the optimal setting that keeps the sensor pretty much centered around .450?

[whittlebeast]

Personally, I never use a narrow band for anything other than locating Lambda of 1 or 14.7 AFR.  Any other number (voltage) is sketchy at best.  Target tune is simply a way better solution.  Those things are way too temperature sensitive away from where they were designed to run.

Andy

[07heri]

Personally, I never use a narrow band for anything other than locating Lambda of 1 or 14.7 AFR.  Any other number (voltage) is sketchy at best.  Target tune is simply a way better solution.  Those things are way too temperature sensitive away from where they were designed to run.

Andy

Why is .981 always thrown around?  Why not closer to stoich?

[glens]

0.981 is pretty close to stoich...

[rigidthumper]

Main λ table replaced the bias table- everything that has a red bar (or is bold, or both- depends on the tuning software), is closed loop. Math is the same- convert 14.68 to 1.0 λ, so if you want 14.3 closed loop, set it to .974λ.   14.4 =.981λ  14.5= .988λ  14.8 = .995λ etc
Narrow band sensors are most accurate at 1.0λ, but there not that bad all the way down to 14.3, and some claim they can go even further.  If the 02 system has a good signal, and reversion is not an issue, the narrow bands work very well for their intended purpose, which is to provide feedback to the ECM.  Closed loop is fine for low load, cruising, but when you increase the load, fuel need to be added, and timing adjusted, to manage heat- that's why the tables look like they do.  Lots of fuel and little timing at big loads,  little fuel and lots of timing at cruise.

[07heri]

0.981 is pretty close to stoich...

Why not .99 or 1.0?  Isn't 1.0 lambda the same as setting an AFR table map to 14.6 with no increase or decrease in CLB? I guess what I'm trying to understand is why on a lambda cal we go much richer than an AFR cal? Is it because the lambda cals don't have a CLB table?  What lambda setting would keep the sensors at an equivalent .450 mv?  On a AFR cal with CLB tables I could stay pretty much centered with a .450 CLB.  What lambda setting would achieve the same?

[glens]

450 is nominally LAMBDA=1 and you can certainly use that if you wish.  The suggested value lies reliably within the comfort zone of the sensors and produces some less heat.  I don't believe the allowable range is really any different between the two schemes.

[07heri]

450 is nominally LAMBDA=1 and you can certainly use that if you wish.  The suggested value lies reliably within the comfort zone of the sensors and produces some less heat.  I don't believe the allowable range is really any different between the two schemes.

OK thanks.  So this would be equivalent to around 800 CLB right?  Isn't that high? 

[wolf_59]

http://harleytechtalk.com/htt/index.php/topic,89042.0.html

450 CLB = 14.68
1.0 Lambada = 14.68
You can use 1.0 lambada to set VE table just like using 450 CLB then set lambada or CLB to what ever the engine needs to run properly
In TTS calibrations you can click on the "tools" tab and the O2 voltage and you can see what = what 

[rigidthumper]

450 is nominally LAMBDA=1 and you can certainly use that if you wish.  The suggested value lies reliably within the comfort zone of the sensors and produces some less heat.  I don't believe the allowable range is really any different between the two schemes.

OK thanks.  So this would be equivalent to around 800 CLB right?  Isn't that high? 

No, 800 CLB would be 14.22 ish. Maybe this pic will clear it up. It shows what = what.

[rigidthumper]

BTW, .981 is used because it is well within the accurate range of narrowband 02 sensors, and is ~ 1/4 AFR richer than stoic, which tends to run a little cooler than stoic without wasting a bunch of fuel.

[07heri]

Im not concerned about AFR.  I'm curious what lambda setting is optimal for the sensor.  It has been stated that .450 mv is the optimal centered point.  Many have said stay at or below 700 CLB.  Now lambda comes into the game and .981 gets kicked around, which is .785mv, well above 700 and much higher than .450. Thus my question about best operating lambda setting to make the sensors most efficient.  If .785 mv is fine for a lambda setting then why all hoopla in past years about this being too high on a CLB table map?  Isn't a narrowband sensor a narrowband sensor?

If it's a NB sensor why would a CLB cal be any different than a lambda cal when considering the most optimal mv?  Again, let's forget about AFR and focus on the best mv operating range. 

450 is nominally LAMBDA=1 and you can certainly use that if you wish.  The suggested value lies reliably within the comfort zone of the sensors and produces some less heat.  I don't believe the allowable range is really any different between the two schemes.

OK thanks.  So this would be equivalent to around 800 CLB right?  Isn't that high? 

No, 800 CLB would be 14.22 ish. Maybe this pic will clear it up. It shows what = what.

[rigidthumper]

I think I understand- you're looking for what will make the sensors last as long as they are supposed to, and be accurate as long as possible?
See how the line is almost vertical from ~200mv to ~750mv? That range is the cleanest,  so the sensors last longest, and accuracy is really good in that stretch.  Keep in mind most guys tune richer than stoic, so your voltage range ( keeping in that accurate, almost vertical area) is 450mv (1.0 lambda, or 14.68 AFR) to 750mv (.993  lambda, or 14.58 AFR)  Sounds like a good area, but it's really only .1 AFR, which in HD terms, aint much.
The typically HD owner doesn't like heat- thus the .981 lambda: ( 785mv) it's close to the accurate area, so it's OK, and is about as rich as the sensor can stand, to give decent life, while providing a slightly cooler mix.

[07heri]

Back to my original question.  If 785 was too high with a CLB map, why is ok with a Lambda map?  Back in the day all the hoopla was you had to run VE's again after timing was changed.  Now, it's ok not to.  Back in the day 785 was too high of a CLB, now it's ok.  What is changing with the NB sensor, if anything?

[rigidthumper]

Narrow bands are heated now, so they get happy/accurate quicker.  I still check VE's after timing changes, so I guess I'm old fashioned. As far as things changing, I hope we get smarter with time/experience? We used to tune everything open loop, but haven't had to in years,,,

[HD/Wrench]

Narrow bands are heated now, so they get happy/accurate quicker.  I still check VE's after timing changes, so I guess I'm old fashioned. As far as things changing, I hope we get smarter with time/experience? We used to tune everything open loop, but haven't had to in years,,,

Use of a Wide band every where is going backwards in today's advancing world ,  WB has its use just like the NB does. I tune with both works out just fine for us

[Jamie Long]

Back to my original question.  If 785 was too high with a CLB map, why is ok with a Lambda map?  Back in the day all the hoopla was you had to run VE's again after timing was changed.  Now, it's ok not to.  Back in the day 785 was too high of a CLB, now it's ok.  What is changing with the NB sensor, if anything?

NbO2 sensor output is non-linear, doesnt matter if you are referring to CLB or lambda. Same rules still apply, the only difference is one needs to be based on a specific fuel stoich value (clb), the other is absolute (lambda)