BM3 Custom Tuning help

[razorlab]

Not arguing, im saying torque should be scaled proportional with power increase and dyno mapping.

I understand how a torque based ecu work this is not limited to bmw even gm uses the same concept.

TCU consumes reported torque from DME, TCU decides line pressure, clamping force, converter-lockup, etc based on reported torque from DME. If the car is actually making more torque than is being reported, the possibility that the TCU isn't giving enough line pressure/clamping force/converter-lockup is higher and clutch slip can happen.

You don't even need to be making a ton of power to have this happen. Stock turbo... clutch slip, converter slip, RPM flare, gear decrease. Increasing Z values in KF_MDIOP_1_TQE confirmed to work.

Before

After

This isn't really even new news. Back in 2020 or so before the TCU torque limiter was found in the tuning apps, a strategy was to REDUCE Z values in KF_MDIOP_1_TQE to under report torque to the TCU so it wouldn't trip the torque limiter. The dark side of this is that the potential of the clutch/torque convertor slipping was much higher.

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[QTR FMS]

TCU consumes reported torque from DME, TCU decides line pressure, clamping force, converter-lockup, etc based on reported torque from DME. If the car is actually making more torque than is being reported, the possibility that the TCU isn't giving enough line pressure/clamping force/converter-lockup is higher and clutch slip can happen.

You don't even need to be making a ton of power to have this happen. Stock turbo... clutch slip, converter slip, RPM flare, gear decrease. Increasing Z values in KF_MDIOP_1_TQE confirmed to work.

Before

After

This isn't really even new news. Back in 2020 or so before the TCU torque limiter was found in the tuning apps, a strategy was to REDUCE Z values in KF_MDIOP_1_TQE to under report torque to the TCU so it wouldn't trip the torque limiter. The dark side of this is that the potential of the clutch/torque convertor slipping was much higher.

thanks for sharing the snapshot, what i find most interesting is that the datalog has clutch slip percent, i didnt know that was available on AT supra I guess that makes the tuning alot easier since you dont need to guess if you have shift flare by ear.

does the supra uses adaptive shift time or static line pressure

 

[omfgzilla]

Not arguing,

I'm pretty sure this is arguing.

I'm saying torque should be scaled proportional with power increase and dyno mapping.

What a mind blowing concept

I understand how a torque based ecu work this is not limited to bmw even gm uses the same concept.

Wow..... what insane knowledge bombs about load based calculations on modern day ECU's

The load to torque table Z values are inner indicated torque, in Nm.
................................

Please make this shithole forum great again.

 

[QTR FMS]

I'm pretty sure this is arguing

what i was trying to say, raising last column to 300% load and 1135nm achieves what bryan is trying to say partially.

my point is the car was not calibrated to go beyond 200% load, so by extending last column you are telling the transmission to raise the line pressure as the car making more power.

now calibrating the torque map based on the car mods such as bigger turbo or intake manifold will definitely require a whole remap on the dyno. Without a dyno you can fudge the number to get the same result but personally i like to only change things based on data available. If i dont have a dyno or virtual dyno and i dont know how much more power the car is making, i would keep the stock torque map because it was built correctly for the stock car and pure800 and downpipe is not really a major change that changes the whole characteristics of the car, it just shifts the power curve into higher rpm and yes it makes slightly more power by doing that and yes a properly calibrated torque map on a dyno is the right way to do it, and the other thing i was trying to say torque shouldnt be over estimated for the sake of transmission tuning its separate calibration.

im running stock turbo which is why my torque map is unchanged and my suggestion was based on my car.

again im not arguing im discussing different way to tune, tuning is subjective and no two tuner tune the exact same way, each has there own preference. When we tune we try to calibrate with the best available data and make some assumptions to fill any gap.

bryan is saying to tune the input which is torque request, i was talking about the output tcu commanded line pressure. Both achieve the same results. Chicken or the egg.

if it seems like im arguing or poking at bryan its because i want to pick his bryan make him explain his point of view more and share knowledge so others can also learn. It not an argument of who is right or wrong , or who has bigger turbo. Its just a friendly discussion for me.

 

[razorlab]

im running stock turbo which is why my torque map is unchanged and my suggestion was based on my car.

Except that is not the proper way. I literally showed stock turbo datalogs for the before/after above. You also have a MT, so all the clamping, line pressure, and torque convertor talk is meaningless. There are however, many KSU tables (clutch-slip monitoring / protection) shared between AT and MT.

bryan is saying to tune the input which is torque request, i was talking about the output tcu commanded line pressure. Both achieve the same results. Chicken or the egg.

Except that is not the full proper way.

For clarity sake, this is not me guessing or making assumptions. All this information is taken from the BMW A2L, the SwCalDocs, and the Funktionsdokumentation.

 

[QTR FMS]

Except that is not the proper way. I literally showed stock turbo datalogs for the before/after above. You also have a MT, so all the clamping, line pressure, and torque convertor talk is meaningless.



Except that is not the full proper way.

For clarity sake, this is not me guessing or making assumptions. All this information is taken from the BMW A2L, the SwCalDocs, and the Funktionsdokumentation.

yes you have corrected me by showing the logs which did prove your point that slip could happen on 190% load and raising the torque map fixed it. There is no argument on this point.

i understand that Funktionsdokumentation explains the information you are saying, im not disagreeing on a properly calibrated torque map, my point is when would you use xhp i believe this is what AT supra users are using to calibrate the transmission shift pressure.

Would you over estimate the torque map or stop at some point and tune the tcu.
Assuming you are not using the dyno to calibrate the torque map and just looking at the clutch slip percentage in log.

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