I'm confused on how basic AT works.

I know AT sets my whole AFR table to .982 lambda or 14.6 AFR and then samples AFR readings at my O2 sensors as I ride.

Assume my VE tables are really far off and my actual AFR is sampling at 12.0 AFR at the O2 sensors across my whole MAP. So my target is set to 14.6 but my pipe sampling is at 12.0. How does the AT make changes to my VE tables when the narrow band sensors can only read AFR between 14.3 and 15.2 and my samples are at 12.0? Assuming the 12.0 example, does AT (1) not make any changes to the VE tables because the sample is outside of the limits that the O2 sensors can read or (2) does AT make incremental changes to the VE tables based on the lowest AFR sample that the O2 sensors read (14.3)? I guess if the answer is (2) and you run enough AT sessions the VE tables would eventually be mapped correctly?

Also, if (2) is correct, what would be the advantage of using the AT Pro or the Target Tune (with wide band sensors), other that the quickness that you could get the VE tables mapped?

Any ideas?

 

Well, you asked, and I'm drunk, deal with it.
I will try to answer, but be advised, I am only slightly ahead of you with this.

You have been asking a lot of questions, and seem to be starting to get the hang of things.
To prove that point, you answered your own questions.

The PV, in Basic mode: if the AFR is out of range of the O2 sensor it will only know which way it is out. It will take a guess at how much to adjust. You keep doing runs until it is within 5%. (When I was first testing the PV on my stock bike I got the VE tables within 2% with about 6 or 7 runs. The PV, with the AT-Pro and it's wide-band sensors did the same job within 3 runs.)

So why use the wind band sensors?

What ever map you start with is not going to be perfect for your bike. With all of the different cams, mufflers, head pipes, intakes, head mods, not to mention tolerances by each manufacturer, etc., no one can possibly have a map perfect for your machine. So the further the map is from your configuration, the more tuning sessions will be needed if the the tuning unit can only guess. The wide band sensors can reduce the number of sessions because it can read the AFR in a broader ranges, reducing the guessing.

So why else?

I know you were part of this discussion that brought the thread off topic:
https://www.hdforums.com/forum/ignit...l#post14949656
(BTW, that thread was originally started to find a way to take the guess work out of tuning spark tables, something you seem to be interested in as well.)

As expressed in that thread, the wide bands can be used to fine tune the VE tables either closer (not having a computer bounce around certain areas) or tune areas which have been preclude from the auto tune sessions.

Since then, I believe you have learned to use the WinPV software to compare tunes. Simply compare one auto tune session to the next and you can see the changes made. Go back and compare your original sessions.

Next, keeping in mind you asked about Autotune Pro.
When using Autotune Pro (or as you say AT Pro) one has access to data they do not have using basic mode. You can log the measured (from the O2 sensors) actual AFR and Lambda values from each cylinder. (Logging values are set when auto tuning, but are selectable when just logging a normal run.) What you don't have, and which you have said you use, are AFF and CLI values. Since the stock O2 sensors are not connected to the ECM it has no way of adjusting these values. Also O2 voltage is irrelevant as the wide bands get their voltage from the AT Pro unit.

Due to unforeseen circumstances
https://www.hdforums.com/forum/touri...l#post14980124
I recently decided to start from scratch and reconnect the AT Pro and start over with my tune.

Due to time constraints and weather I have only done two tuning runs, and a logging run after each. I have been able to adjust areas outside of the set auto tune area by the data supplied.

Hope this answered your questions. Just keep in mind, I have no experience with the new TT ( Target Tune) It is my understanding that with that you would have access to the AFF and CLI logs, as well as the AFR and Lambda, and be able to leave it connected to run in closed loop all the time, but that is only from what I have read.

 

Yes that is pretty much spot on- plus, TT does not alter your timing for auto tuning or require a set AFR- it will use all the AFR values as-is in the lambda table. it does work very well.

 

AT basic is very creative in how it works. Since NB sensors can only accurately detect a narrow AFR range, the auto tune process must set all AFR values to 14.6, and, it drops the spark timing 4 degrees across the board for safety / ping prevention. By running an auto tune with every lambda cell set to 14.6, the auto tune system tries to tune the VE's so they are accurate at 14.6. It is estimated that by doing this, VE will also be reasonably accurate at any AFR outside of closed loop once AT is turned off / normal riding. I personally did not find it to be very accurate with doing auto tune basic sessions then operating the bike with a mostly open loop, richer performance map.

Outside of the narrow band sensor's closed loop detection range, it only knows "rich" or "lean". it has no idea what the actual AFR value is and tries to guess at adding or removing fuel to meet whatever the actual lambda target is - 13.2 etc. so it's only a 'best guess' scenario with open loop AFR targets and NB sensors.
Realistically, narrow band sensors were only developed to help vehicle manufacturers meet stricter epa standards and improve fuel economy. Narrow band sensors were never meant to be a tuning tool or sensor for performance applications. it is a limited system by design and was created with a specific task in mind - economy and low cost to implement on vehicles by mfr's. the fact that DJ got these NB sensors to operate with the PV in the manner they did is quite an accomplishment.

With wide band sensors, they are accurate at every AFR ratio and can run the entire range closed loop. by doing VE tuning with wide band sensors, you have much more capable sensors to tune the VE table with any range of lambda table values. there is no guessing like with NB sensors. Dynos and pretty much all performance oriented efi systems will use wide band O2, always.

 

Thanks for your response.

I followed you up until you stated that the "wide bands can be used to fine tune the VE tables even closer (not having a computer bounce around certain areas) or tune areas which have been precluded from the auto tune sessions."

If AT operates as you indicate above and sets the AFR MAP to 14.6 across the board and then monitors the O2 sensors to make changes to the VE tables, why would I need to use wide band sensors? AT without the wide bands will just make small incremental changes to the VE tables until the target 14.6 AFR is achieved.

How are the wide band sensors going to enable me to get into MAP (KPa) areas that were precluded from the areas that were sampled in the basic auto session?

Thanks.

 

I'm confused. If I set the entire AFR table to 14.6 and use the narrow band sensors (via AT) to adjust the VE tables to achieve that 14.6 target (based on what they read in the pipes) across the entire AFR table, why do I need to use wide band sensors to do this?

So it may take a little longer (more auto tuning sessions). Won't this work?

 

Isn't the whole issue with auto tuning on the street the inability to populate certain VE cells rather than using narrow bands versus wide bands?

I mean couldn't you set the AFR table to 14.6 across the board, use the narrow bands and use the brake on a dyno to hit all of the VE cells?

 

That is how the basic tune with vision is advertised.


Both sensors have their limitations and their strength. They both have trade offs. It is best to understand these and use the best tool for the job. I use both while tuning on a dyno. They both have their place. I also use them on performance builds. I have a 04 124 making over 160hp running out there that cruises light load with close loop NB sensors. Don't buy into the all or nothing closed loop and WB's are magic BS.

 

You read through, understood, and applied concepts from the TTS Guide to tuning spark tables with your PV, but don't understand wide-bands?


When did I ever say you need wide bands?
They are another tool in a tool box to make things easier.

 

......your obviously still drunk.

Yes I was able to follow the TTS Guide and adjust my spark tables.

I didn't say that I don't understand the difference between wide and narrow bands or that I didn't know what a wide band is. I have a manual from PV and also one from TTS. To use auto tune, they both show putting the entire MAP in the closed loop at 14.6 and auto tuning with the narrow bands. PV does it for you so the directions state and it looks like it is a manual process in the TTS Guide. So basically after my map is converted to an auto tune MAP (all cells set to 14.6) my narrow bands are going to read KPa and RPM in MAP areas that were previously open loop and suggest corrects to my VE tables that strive to get my AFR to 14.6. My question was that if my entire MAP at 14.6 is in the closed loop why do I need wide bands to auto tune? Won't the narrow band ones work? If it works like you said above, I can see that it would be faster using AT Pro with wide bands, but won't I eventually get there using the narrow bands, albeit a little slower?

I didn't say that you said I need the wide bands, I asked why I would need them given the scenario above.