I understand that these re-program the ECM. However, I have also read that the ECM essentially does some re-learning as time passes. So, my question is this. When you tune with one of these using the auto tune feature do you have to keep running auto tune periodically to keep the tune right? It seems to me that you would because if the ECM can learn it is continually trying to take your bike back to the 14.7 range in AFR after your original tune is completed.
Thanks guys.

 

Auto Tuning or Smart Tuning as in the case of the SEPST is a process to calibrate the VE Tables to reflect the actual VE which may have changed due to modifications or perhaps a severe change in altitude/climate.

The accuracy of the VE Tables is necessary to insure that the system faithfully reproduces the values in the AFR table.

14.7 is a stoichoimetric value. Putting this value in a cell in the AFR table causes this cell to operate in closed loop mode bringing O2 sensor feedback into play. The sensor toggles between too much fuel and not enough fuel causing the ECM to adjust accordingly adding or subtracting fuel. As I understand, the more accurate your VEs then the fewer adjustments are made by the ECM to achieve the 14.7. The Adaptive fuel table tracks these adjustments and that is the learning you speak of, a cell in the VE table may say 97%, but based on this process the Adaptive Fuel table may have an actual value of 89%.

Any value other than 14.7 in the AFR table causes that cell to function in Open loop mode w/out feedback from the O2 sensors. So if you specify that you want a value of 13.8 in a specific cell, then the system depends on the accuracy of the VE table to reproduce this value. I believe the ECM may also take values from the Adaptive Fuel Table into account as well.

This is how I understand the system works. If I am mistaken on any point I am open to correction.

So.... Does this help?

 

Maybe this will add more understanding.

The object of tuning is to bring the tables closer to what your bike needs.

Waiting on the ECM to "Learn" takes forever and is handicapped by a margin of 5% or less. In other words, the ECM will only adjust so much.

So, tune your bike within 5% using a real tuner then let the ECM adjust in closed loop (normal riding areas).

And for last... there is no such thing at auto-tune. There must be some human/computer intervention to write the corrections to a new calibration and flash the ECM.

 

software error. double post

 

Yeah, on a Thundermax, here's how it works. You load a base map, and while you ride the t-max ECU is making adjustments to that map to hit the AFR that is set in the map...and it stores the data. It's not going to overwrite or update your map permanently until you tell it to using the "Automap" function in the t-max software. At least that's how I understand it.

 

Correct.... There must be some human/computer intervention to write the corrections to a new calibration and flash the ECM.

 

Once tuned, AND tuned correctly, there will be very little drift in things. A crappy tune will try to use the 'learning functions' and the tune can drift a bit.

This is why PV, TTS, AND SEPST all want us to get withing 5% of the VE changing. Once the VEs are below 5%, the tune should be good to go.

 

: icon_twocents:

 

Nit picking maybe, but for clarification you mean the VE Tables. Right?

 

I don't think that is nit picking. Think it is a great question.

Just speaking about TTS here...

Cam Selector is a table that must be correct before you can get good VE's

VE's are the next on the list and are the most important right after Cam Selector.

AE adjustments when looking for that great snap throttle adjustment.

DE adjustments for decel assistance or VE adjustment to stop decel pop.

Warm timing table to assist with warm knocking, EGR for smooth acceleration/power.

The list goes on...

My thoughts are that most think setting VE's are good enough and let everything else ride. Just me, but I lean on the other tables to make a "good enough" calibration much better.