[XPbIM3]

I am running a mercedes m104 + 722.433 transmission under speeduino ECU. This tranny is little weak for 3.2 engine.
Mercedes manual states a mechanism for timing retatrd under shifting procedure for limiting the engine torque, so transmission can survive full throttle shift a little longer.

I decided to implement that retarding mechanism to let shifts became smoother.
Since this is a mock-up I changed a MT flatshift code to do the following:

• Detect when AT start to engage a next gear. Detection is done by monitoring currentStatus.rpmDOT. If it is -500 or more negative - we are in gear change event.
• Check for conditions: if we have TPS more than , say 10%, and MAP more than. say, 40 kPa and we still in shift event - fix timing as a 5 BTDC to limit torque.
• Optional: if all of the conditions are met, and current RPM is very high - we should do a hard limit to ensure a rapid drop of rpm's. This can help to shift under hevay load: WOT+kickDown pressed.

Actually tried all this on my w124 and it worked well! Really pleased how it all came out. Maybe a hard cut should be polished a little.

Again, all this is a mock-up, I didnt do a pull request because all of this is hardcoded, no EEPROM values reserved for parameters, some MT flatshift code changed.etc... but if someone is interested in this feature in master branch - let me know, maybe this really should be pushed to git.

[rallikuski]

I see this can save even bigger 722.3 transmissions with turbo setup etc...

[XPbIM3]

I see this can save even bigger 722.3 transmissions with turbo setup etc...

correct.

furthermore You can adjust a pressure modulator for more pressure, and flatten out shifts with timing retard and ignition cutoff to achieve a smooth and quicker shifts. (Also sick pop-pop exhaust sound during shift)


the problem now is EEPROM mappings for parameters are liitle too tight to insert some more values to habdle AT flat shift.

[dazq]

This would be well worth putting in a pr for.
There is much scope to extend it to cover serial and even can requests later on once this initial part is included.
Most electronic transmission will send some kind of torque reduction request to the engine and the engine usually replies that it has done what was requested.these additional features could be added later to keep this initial pr simpler.

[XPbIM3]

ok, i will consider to do a pull request and post some work progress here too.

[rallikuski]

I see this can save even bigger 722.3 transmissions with turbo setup etc...

correct.

furthermore You can adjust a pressure modulator for more pressure

Yes, that is what i did to make my old 722.3 shift better...

[PSIG]

• Detect when AT start to engage a next gear. …
• Check for conditions: … fix timing as a 5 BTDC to limit torque.
• Optional: … hard limit to ensure a rapid drop of rpm's. …

Good stuff. The basis of all this is detecting if shift is occurring, or continues to occur. If Shift Detection (SD) is the focus, then parameters and options can be held open. For example, SD can simply invoke DFCO instead or in-addition to specified timing change or cut. As DFCO is a stand-alone specification, no further code would be required, and optionally the timing could be retarded when DFCO is released by SD.

Combine other options such as timer action on detection, and once SD detects, any action could be based on entered time rather than non-shift condition detection. This would emulate popular racing and motorcycle engine control on-shift, while allowing a stand-alone existing function to be called, i.e., rev-limiting parameters, launch control, hijacking flex-fuel functions for fueling and timing alterations, etc.

TL;DR — Perhaps consider making SD a basic detection function, with the ability to call various other optional functions that suit the application, based on either continued detection or time?

[XPbIM3]

https://github.com/XPbIM3/speeduino/tree/AT_Flatshift


Using this particular code on 3.2 m104 mercedes. Works nice.
Compile and upload with VSCode.

A screen of AT flatshift configured section is below
The settings are:
-Enable AT flat shift - enables or disables flatshift.
-RPM lower threshold - from what RPM flatshift ignition retatding will be applied
-RPM upper threshold - an upper possible rpm to apply retard. If engine rpms are higher than this threshold a hard ignition cut-off is applied.
-Ign advance on lower threshold - an absolute timing BTDC degrees to set ignition to when shift occurs on lower rpm threshold
-ign advance on upper threshold - an absolute timing BTDC degrees to set ignition to when shift occurs on upper rpm threshold. An ignition values in between low and high rpm thresholds will be interpolated lineary.
-TPS threshold - a minimum amount of TPS required to apply flatshift.
-MAP threshold - engine MAP readings must be above this threshold to enable flatshift
-RPM drop threshold - using this threshold Speeduino detects if AT is in gear change event. typically something about "-500" is sufficient to detect upshift.

This algorithm supports only upshifts. No downshifts are detected for now.
Contact me if any questions.

[XPbIM3]

Someone hit me with an email recently to update my AT_flatshift fork for 2022_02 firmware base.
Here it is:
https://github.com/XPbIM3/speeduino
grab an " AT_Flatshift" branch - it is a 2022_02 based.
https://github.com/XPbIM3/speeduino/tree/AT_Flatshift


Or here are the source code and prebuild firmware with ini definition file for TunerStudio:

AT_flathift_202202_Source.zip

(4.84 MiB) Downloaded 633 times

prebuilt_firmware.zip

(395.73 KiB) Downloaded 646 times

NOT FULLY TESTED!
PROVIDE FEEDBACK IF ANY!

[dzener]

Hello, do you intend to update to version 202207? I don't know anything about programming, and I'm in need of a flatshift to AT too, my transmission is slipping a little when shifting at full load.