follow ft86club on our blog, twitter or facebook.
FT86CLUB
Ft86Club
Speed By Design
Register Garage Members List Calendar Search Today's Posts Mark Forums Read

Go Back   Toyota GR86, 86, FR-S and Subaru BRZ Forum - FT86CLUB > Technical Topics > Software Tuning

Software Tuning Discuss all software tuning topics.


User Tag List

Reply
 
Thread Tools Search this Thread
Old 11-26-2020, 12:00 AM   #1
Wayno
Senior Member
 
Wayno's Avatar
 
Join Date: Apr 2014
Drives: Toyota 86 GTS
Location: Australia
Posts: 1,122
Thanks: 451
Thanked 881 Times in 419 Posts
Mentioned: 204 Post(s)
Tagged: 0 Thread(s)
6AT - How to increase line pressure i.e. shift firmness

Requirements:

- 6AT

- IQ > 55 so you don't post in this thread asking if modifying calc tq will fix your syncho issues or anything else 6MT related.

- The following tables defined:
-- Requested Torque A
-- Requested Torque B
-- Requested Torque Base
-- Calculated Torque A
-- Calculated Torque B

TDLR:
Multiply every data cell in the above tables by the same factor to increase the line pressure by that amount.

DO NOT MODIFY:
- Any axis on the above tables.
- Target throttle plate position table.

HOW MUCH TO MODIFY:
- Increasing cacluated torque affects shift firmness in both NORMAL and SPORT modes (and assume SNOW also).
- Manual mode seems to be unaffected and the TCU and/or valve body have their own static values for the line pressures.
- I've briefy tested a 40% increase which makes shifting in normal mode feel more like sport mode, (only without the sport mode shift points obviously). It makes shifts in SPORT mode HARSH. Consider this in FI application where sport mode is not used.
- I'm going to be testing 20%, which will hopefully improve normal mode while not adversely affecting sport mode too much.

Personally I never use sport and think it's a wank, but regardless wouldn't make any tune changes that could push the valve body output high enough that it feels like it could do damage.

LONGER VERSION:

Under normal circumstances in every gear in both normal and sport modes, Calculated Torque A is used to determine both:
- How hard to shift
- When to shift

Calculated Torque B is used for low IAM, safe mode, etc, and blended with very complicated logic. Lookups on both Calculated Torque tables are done using multiple load values, not only the final calculated load value, adding extra complexity.

HOW THE ECU UP SHIFTS
- Ingnition retard,
- then RPM drops,
- then TCU sends updated gear number to ECU to indicate shift complete.

HOW HARD TO SHIFT:

To increase line pressure, increase the values in Calculated Torque A.

WHEN TO SHIFT:

The ECU determines when to shift by comparing the value of calculated torque to the value of requested torque.

If you were to increase only Calculated Torque A, then the ECU is going to think it's making more power than required and up (short) shift to a higher gear, resulting in always being under-powered.

If you were to decrease only Calculated Torque A, then the ECU is going to think it's making less power than required so it will hold gear longer, but will have lower line pressure during/after shifting, to the point where the ECU will attempt to cut timing a second time to invoke an up shift again because the TCU is slow to report the new gear to the ECU.

After adjusting Calculated Torque, you must also increase Requested Torque by the same factor to maintain the exact same shift points.

The ECU determines throttle position under normal driving by looking up the value in Requested Torque B based on accelerator angle, then dividing the requested torque value by the requested torque base value, then looking up the target throttle position based on that fraction.

Therefore, you need to increase both Requested Torque and Requested Torque Base by the exact same factor to result in the same calculated fraction.

In addition, because Requested Torque Base has now been modified, you must also update Requested Torque A and Calculated Torque B to keep them all in sync.

So, the list of tables modified in order becomes:
- Calculated Torque A
- Requested Torque B
- Requested Torque Base
- Requested Torque A
- Calculated Torque B


Example to illustrate multiplying all 5 tables by the same factor:
Attached Images
  

Last edited by Wayno; 11-26-2020 at 09:39 PM.
Wayno is offline   Reply With Quote
The Following 4 Users Say Thank You to Wayno For This Useful Post:
73TORANA! (02-24-2021), Kodename47 (11-26-2020), steve99 (11-26-2020), whataboutbob (11-26-2020)
Old 11-26-2020, 04:36 AM   #2
Kodename47
Senior Member
 
Kodename47's Avatar
 
Join Date: Oct 2012
Drives: UK GT86
Location: UK
Posts: 3,030
Thanks: 185
Thanked 1,605 Times in 1,102 Posts
Mentioned: 148 Post(s)
Tagged: 1 Thread(s)
Quote:
Originally Posted by Wayno View Post
The ECU determines throttle position under normal driving by looking up the value in Requested Torque B based on accelerator angle, then dividing the requested torque value by the requested torque base value, then looking up the target throttle position based on that fraction.
Need to update this paragraph Wayne.

Otherwise, top write up!!!
__________________
.: Stealth 86 :.
Abbey Motorsport/K47 Tuned Sprintex 210 Supercharger

Kodename 47 DJ:
Soundcloud / Instagram / Facebook
Kodename47 is offline   Reply With Quote
 
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Wait a sec...is it fine to park ON the line, so long as you're not BEYOND the line? tzhu07 Off-Topic Lounge [WARNING: NO POLITICS] 59 11-08-2020 08:40 PM
Exhaust line and Back Pressure RG4L Engine, Exhaust, Transmission 20 06-20-2020 08:29 AM
Help! Brake line leakage after steel braided line install. ysu Suspension | Chassis | Brakes -- Sponsored by 949 Racing 26 02-09-2020 10:38 PM
Brake firmness/pedal feel Hyper4mance2k Suspension | Chassis | Brakes -- Sponsored by 949 Racing 40 05-22-2019 12:22 PM
Adding in line fuel pressure regulator KGZ86 Engine, Exhaust, Transmission 13 07-07-2016 05:15 PM


All times are GMT -4. The time now is 12:33 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2021, vBulletin Solutions Inc.
User Alert System provided by Advanced User Tagging v3.3.0 (Lite) - vBulletin Mods & Addons Copyright © 2021 DragonByte Technologies Ltd.

Garage vBulletin Plugins by Drive Thru Online, Inc.