DCT - Possible xHP Flash

aus335iguy

Major
Nov 18, 2017
1,516
So, ive been chatting to @Seb335i and given that XHP flash is nearly here custom flashing of the DCT will soon be a thing. As @jyamona alluded to earlier we just need as much of the XDF defined... Moreover if someone could build custom roms for us to flash In it would make my day... @Olza
Im putting my order in for you to build me a rom now and im willing to pay for a rom
  1. Uses standard 2.56 final drive
  2. Has GTS drivelogic (90ms shifts, adjustable launch etc)
  3. Uses the M3 GWS
  4. Uses the M3 display on the KOmbi
  5. No upshift on loss of traction
  6. other stuff
Is this even possible for you to create a BIN to do that though ?
 
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Olza

Specialist
Feb 2, 2020
87
Minsk, Belarus
So, ive been chatting to @Seb335i and given that XHP flash is nearly here custom flashing of the DCT will soon be a thing. As @jyamona alluded to earlier we just need as much of the XDF defined... Moreover if someone could build custom roms for us to flash In it would make my day... @Olza
Im putting my order in for you to build me a rom now and im willing to pay for a rom
  1. Uses standard 2.56 final drive
  2. Has GTS drivelogic (90ms shifts, adjustable launch etc)
  3. Uses the M3 GWS
  4. Uses the M3 display on the KOmbi
  5. No upshift on loss of traction
  6. other stuff
Is this even possible for you to create a BIN to do that though ?
If xhp will allow sign and write custom bins - why not. Assume that they didnt crack signature, just somehow bypass check via own bootloader or something. Also there should be one base program version - latest 135/335 or old GT.

0. Didnt see ordinary 135/335 program but in GT program we can switch to use stock GWS
1. Ive read about up shifts, can it be only dsc issue? Ill look into.
2. Upshift blurbs - what is realization? I thought also it is only engine and exhaust things? We can increase interventions to dme for late ignition.
3. I can disable dsc intervention offset during shifts
 

carabuser

Specialist
Oct 2, 2019
92
If xhp will allow sign and write custom bins - why not. Assume that they didnt crack signature, just somehow bypass check via own bootloader or something. Also there should be one base program version - latest 135/335 or old GT.

0. Didnt see ordinary 135/335 program but in GT program we can switch to use stock GWS
1. Ive read about up shifts, can it be only dsc issue? Ill look into.
2. Upshift blurbs - what is realization? I thought also it is only engine and exhaust things? We can increase interventions to dme for late ignition.
3. I can disable dsc intervention offset during shifts
What does the telegram between the DME and TCU look like?

I ask because one of the big problems for DCT users is the fact we are limited to 18.5PSI, when targeting above that the shifts go bad. Is boost or load sent to the TCU or is it just reported torque?
 

RSL

Sergeant
Aug 11, 2017
485
What does the telegram between the DME and TCU look like?

I ask because one of the big problems for DCT users is the fact we are limited to 18.5PSI, when targeting above that the shifts go bad. Is boost or load sent to the TCU or is it just reported torque?
Can't imagine boost is sent, but it's definitely on boost ceiling. Maybe it's a flag that hasn't been accounted for or TCU does have it's own limit that hasn't been able to be adjusted up to match.

I don't know what they do to raise the ceiling for M boost, but everything would seem to indicate that param, or something else that uses it, treats it as signed. 7FFF or lower, everything is fine. 8000+ fails on shifts and those would all be negative values.

Even though boost target does what it's supposed to on M Boost, I'd bet money something obviously important to DCTs sees it as a negative when raised.
 

carabuser

Specialist
Oct 2, 2019
92
Can't imagine boost is sent, but it's definitely on boost ceiling. Maybe it's a flag that hasn't been accounted for or TCU does have it's own limit that hasn't been able to be adjusted up to match.

I don't know what they do to raise the ceiling for M boost, but everything would seem to indicate that param, or something else that uses it, treats it as signed. 7FFF or lower, everything is fine. 8000+ fails on shifts and those would all be negative values.

Even though boost target does what it's supposed to on M Boost, I'd bet money something obviously important to DCTs sees it as a negative when raised.
You don't even need M Boost to go above the boost ceiling. From what I read in the code the boost ceiling is a maximum value for the boost target part way through the target boost pressure routine but you can use that boost target modifier table I posted in the advanced tuning section to set the target to whatever you want since it's applied right at the end of the routine. I set it to 0.9 as a test and I was targetting 20.5PSI. I was getting nasty throttle closures and terrible shifts though so I didn't go any further.
I just assumed it was a TCU problem and left it alone after that. If I know for sure the TCU doesn't receive either charge pressure or load then I'll dive back into the documentation and try figure it out.
 

azshantris

Specialist
Aug 27, 2019
65
I'm extremely curious how this could potentially benefit any of us who have already done a GTS conversion. At least line pressure? Or perhaps switching back to 2.56, though to be fair I really don't mind 2.81.
I've seen MHD say they might have 2-step coming for DCT which would be pretty cool but possibly an xHP MHD hybrid? Almost need them all in one app lol
Definitely excited to see what they put out!
And of course being N55 makes it extra weird 😅
 
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doublespaces

Administrator
Oct 18, 2016
8,704
AZ
I'm extremely curious how this could potentially benefit any of us who have already done a GTS conversion. At least line pressure? Or perhaps switching back to 2.56, though to be fair I really don't mind 2.81.
I've seen MHD say they might have 2-step coming for DCT which would be pretty cool but possibly an xHP MHD hybrid? Almost need them all in one app lol
Definitely excited to see what they put out!
And of course being N55 makes it extra weird 😅
Aside from line pressure you'll get shift points I presume along with more adjustment of the levels of aggressiveness. Also I can imagine launch control in any setting, etc

For those without the GTS conversion, I suspect they will get the same stuff but not sure how they will overcome the lack of a physical button. A few ways they could approach that I guess.
 
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RSL

Sergeant
Aug 11, 2017
485
You don't even need M Boost to go above the boost ceiling. From what I read in the code the boost ceiling is a maximum value for the boost target part way through the target boost pressure routine but you can use that boost target modifier table I posted in the advanced tuning section to set the target to whatever you want since it's applied right at the end of the routine. I set it to 0.9 as a test and I was targetting 20.5PSI. I was getting nasty throttle closures and terrible shifts though so I didn't go any further.
I just assumed it was a TCU problem and left it alone after that. If I know for sure the TCU doesn't receive either charge pressure or load then I'll dive back into the documentation and try figure it out.
You need it to raise the ceiling though. The only time I messed with low divisors was on a scaled map, so I couldn't confirm.

I've never seen a boost param in DKG, but that doesn't mean it may not be getting one. There are also torque limits through the EGS, but not sure they apply to DCT. An internal torque for sure goes to the TCU, but that's about the only thing I can say with certainty. It seems like it has everything else needed internally.
 

RSL

Sergeant
Aug 11, 2017
485
@carabuser externals to the DCT TCU:

0xCF10 message (request wheel torque drive train, PT-CAN) from the LDM
0xCF11 message (outside temperature / relative time, PT-CAN) from the instrument cluster
0xCF12 message (operation of gear selector switch 2, PT-CAN) from the GWS
0xCF13 message (torque 1, PT-CAN) from the motor control
0xCF14 message (torque 2, PT-CAN) from the motor control
0xCF15 message (torque 3, PT-CAN) from the motor control
0xCF16 message (torque request ACC, PT-CAN) from ACC
0xCF17 message (torque request DSC, PT-CAN) from the DSC
0xCF18 message (speed, PT-CAN) from the DSC
0xCF19 message (mileage / range, PT-CAN) from the instrument cluster
0xCF1A message (terminal status PT-CAN) from CAS
0xCF1B message (steering wheel angle, PT-CAN) from the DSC
0xCF1C message (motor data, PT-CAN) from the motor controller
0xCF1D message (wheel pressures, PT-CAN) from the RDC
0xCF1E message (wheel speed, PT-CAN) from the DSC
0xCF1F message (wheel torque drive train 2, PT-CAN) from the engine control
0xCF20 message (wheel tolerance adjustment, PT-CAN) from the DSC
0xCF21 message (raw data longitudinal acceleration, PT-CAN) from the DSC
0xCF22 message (seat occupancy / belt contacts, PT-CAN) from SSFA
0xCF23 message (status trailer, PT-CAN) from AHM
0xCF24 message (status DSC, PT-CAN) from the DSC
0xCF25 message (status contact handbrake, PT-CAN) from JBBF
0xCF26 message (ZV and valve status, PT-CAN) from CAS
0xCF27 message (operation of gear selector switch 2, LIN) from the GWS
0xCF28 message (OBD data motor, PT-CAN) from the motor control
0xCF29 message (status MSA, PT-CAN) from the motor control
0xCF30 signal from the DSC: speed wheel VL
0xCF31 signal from the DSC: speed wheel VR
0xCF32 signal from the DSC: speed wheel HL
0xCF33 signal from the DSC: speed wheel HR
0xCF34 signal from the motor control: Torque_act_DME
0xCF35 signal from the motor control: brake light switch
0xCF36 signal from the engine control system: accelerator pedal angle
0xCF37 signal from the DSC: Status_DSC
0xCF38 signal from the motor control: speed_idle_speed
0xCF39 signal from CAS: status terminal 15
0xCF3A signal from CAS: Status key inserted
0xCF3B signal from FRM: Status door contact driver
0xCF3C signal from SSFA: class weight seat
0xCF3D signal from GWS: signal implausible
0xCF3E signal from the motor controller: motor speed
0xCF3F signal from CAS: Status Passive-Access active
0xCF40 signal from CAS: Status key valid
0xCF41 signal from SSFA: Belt buckle switch FA
0xCF42 signal from the DSC: All 4 wheel speeds invalid
 
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RSL

Sergeant
Aug 11, 2017
485
Thanks a lot for that. Very interested to see that both torque request and pedal position are referenced.

I wonder how the TCU knows the boost has gone over the limit. Maybe it's a bit in the "motor data" status word that goes across.
Sure thing, found those in ediabas today. I have no idea what's in that motor data, but seems there's really only a few things it could be.

I was going to try to log today and make some comparisons, but it's raining. Maybe tomorrow. I've generated the same crappy shifts playing with things in the DME (with stock ceiling), so if the ceiling increase is also raising/allowing a higher torque somewhere than the TCU will currently accept, we could potentially tune it back down to keep good shifts with the higher ceiling.
 

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