Throttle Linearity Settings

[arghx7]

Well, what is ideal? If you make it more linear, you are going to dull the response somewhere. It's basically a logarithmic fit in your scatter plot.

[King Tut]

Originally Posted by mad_sb

I posted how all the tables work months ago. I'm on my phone in the middle of moving so I can't dig it up right now, but if you search for threads started by me you will find it.

I remembered you made a thread about torque requested values and such, but I guess I didn't tie that to the throttle response of the engine. I will go read your thread again.

[arghx7]

For posterity's sake, here is the info from @mad_sb , who has done a great job contributing to this forum.

Here is the original thread: http://www.ft86club.com/forums/showt...796#post719796

Here is his thread on tuning the cam phasers (AVCS):

http://www.ft86club.com/forums/showthread.php?t=29679

Here is his thread on open/closed loop transition:

http://www.ft86club.com/forums/showthread.php?t=30418

And here is his thread on E85:

http://www.ft86club.com/forums/showthread.php?t=39375

Please note that those tuning threads are in the Engine, Exhaust, Transmission section because this software tuning section did not exist at the time. The original post on throttle tuning is quoted below:

Originally Posted by mad_sb

Greetings,

So I have been messing around with BRZedit since yesterday afternoon and I have some info I wanted to share with the group of BRZedit users. Mods, please feel free to move this post into an ECU Tuning sub forum as I am sure there will be many more threads like this in the months to come.

Anyway. After a little messing around I think i have a good grasp of how the Drive By Wire system works for the most part and I have a bit of info that will save some of you some head scratching and wasted time.

First lets take a look at the stock maps:



As I was looking around at the maps I came across the Wide Open Throttle Torque Limits ... Thinking this was similar to the torque limit maps we have in Evo / Ralliart / 4B11T land I decided to smooth out the 2D and raise up the limits. After wards my logs showed some throttle closure right around the torque dip. So, I made another pass at increasing the limits and taking some more logs.... Throttle closure got worse...

Finally it dawned on my this is not a Limit table but a base table that is used to calculate where you fall on the Throttle Angle - Torque Request table. The result from this table lookup sets the throttle angle. Lets have a look at my logs and the tables that produced them:



So, what it appears happens is this:

1. Mash the go pedal to the floor
2. ECU looks up the requested torque from Accel Pedal - Torque Request (Sport Mode)
3. ECU looks up value from Wide Open Throttle Torque Limit
4. AP-TR / WOTTL = Torque Ratio (%)
5. ECU looks up Throttle angle from Throttle Angle - Torque Request table

I have looked at the data over and over again, the only way the math works out is if the Torque ratio = AP-TR (sport mode) / WOTTL. This is only for WOT. I have not dug into the part throttle stuff yet. The Calculated Torque A and B tables must come into play somewhere, possibly for part throttle and not for WOT.

Long story short... Do not raise the Wide Open Throttle Torque Limit table beyond where your calculated torque values / Accel Pedal Torque Request lookups put you. If you do, you will end up with less than the desired throttle opening angle.

May I add that Subaru's torque control is very crude, assuming we are understanding it correctly. It seems to be common among Japanese OEM's. Using a simple lookup table is a primitive way to do it. Much more advanced control systems in mass produced vehicles are model based, to the point of calculating cylinder pressures.

[Unicorn]

Originally Posted by arghx7

Well, what is ideal? If you make it more linear, you are going to dull the response somewhere. It's basically a logarithmic fit in your scatter plot.

Dear arghx7,

Looking at comparative graphs from other vehicles, including other types of Subaru, they do vary. Of course, this is done in the final stages of calibration by the driveability teams (pushed by marketing) to give the some kind of intended driver experience.

It may look a reasonable curve, on some engines, perhaps normally aspirated, or stock, but when you appreciate how much say 1.3g/rev load is at 2000 rpm, you soon realise it's a bit 'too much'. It just needs dampening down a bit, like throwing a wet towel over a wild hyena.

p.s. you are on the 'cool wall' on the rainbow

Yours faithfully,
Unicorn

[mad_sb]

sorry for the brevity, wrapping up a cross country move... we need a spread sheet or program that can take the 3 input tables and create a 3d final output table.. i started working on something but have not had time to finish.

I believe the cruise control system does direct lookups against the torque ratio table (throttle angle torque request) so it is s good idea not to modify that one, at least in the lower throttle angle areas. I dug that info our of a romraider post many many months ago, may not apply, but just in case... something to be aware of.

[King Tut]

Originally Posted by mad_sb

sorry for the brevity, wrapping up a cross country move... we need a spread sheet or program that can take the 3 input tables and create a 3d final output table.. i started working on something but have not had time to finish.

I believe the cruise control system does direct lookups against the torque ratio table (throttle angle torque request) so it is s good idea not to modify that one, at least in the lower throttle angle areas. I dug that info our of a romraider post many many months ago, may not apply, but just in case... something to be aware of.

Interesting. I would love to see that spreadsheet. The main thing I noticed immediately when swapping from my Visconti tune to my FA20Club tune was that I now pulled boost in cruise control where I didn't before. Perhaps Toni modified the torque ratio table.

[pro_turbo]

Originally Posted by Unicorn

Dear Unicornettes,

Please find below latest data from the rainbow with regards to stock torque control tables used with a Sprintex/Innovate supercharger (charge cooled):






Where
I hope it is obvious that this is not ideal.


Yours sincerely,
Unicorn

I cant open it. Cam ypu just screenshot it

[bcj]

New Ultra avatar



Missed it first time around.