Torque relation to AT shifts?

Sava666

Corporal
Dec 14, 2020
141
19
0
Hi all. I read from a tuner about the engine-transmission interface logic. The logic is that the tcu receives a signal from the ecu and the transmission reacts based on the torque requested.

Based on how much torque will be applied and how much the throttle is open. Not exactly how much torque IS applied, but how much SHOULD be applied. Under this condition, it shifts down in proportion to the amount of torque that should be applied. Consequently, when you ask for more torque, it a) shifts down a gear earlier (i.e. jumps from 5 to 3), and b) does so faster.
This may not be new to experienced tuners.

So, is he talking about our "Requested Torque (driver)/Torque Requested % (high/low)" tables
Has anyone had any real benefits, such as quicker gear changes? If yes, can you share some information?
 

carabuser

Lieutenant
Oct 2, 2019
646
1
503
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UK
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Z4 35i & 335i
I haven't looked at the code for the AT, only the DCT but I do know what the data transmission between the 6AT and the DME is a lot simpler.
The main value the 6AT looks at is pedal position and the calculated torque from the engine.

The amount of clamping pressure and the rate it is applied is based off the calculated engine torque from the engine and the gear selection is based off pedal position.
There's no tables in the DME that will alter that behaviour. If you change the pedal mapping in the DME it will not be altered in the TCU. If you want to improve the 6AT then you need to tune the trans. xHP have some nice OTS maps.
 
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Sava666

Corporal
Dec 14, 2020
141
19
0
I haven't looked at the code for the AT, only the DCT but I do know what the data transmission between the 6AT and the DME is a lot simpler.
The main value the 6AT looks at is pedal position and the calculated torque from the engine.

The amount of clamping pressure and the rate it is applied is based off the calculated engine torque from the engine and the gear selection is based off pedal position.
There's no tables in the DME that will alter that behaviour. If you change the pedal mapping in the DME it will not be altered in the TCU. If you want to improve the 6AT then you need to tune the trans. xHP have some nice OTS maps.
Xhp already maxed out + Drag mode enabled,
Thought there are still some secret sauce tables?
Can you elaborate on what do these tables regulate? (Requested Torque (driver)/Torque Requested % (high/low))
 

carabuser

Lieutenant
Oct 2, 2019
646
1
503
0
UK
Ride
Z4 35i & 335i
Torque request is the pedal mapping to torque request. Everything in the DME is done using torque values.

When you press the pedal you are requesting a certain amount of torque from the engine. The DME works out how much throttle, timing and boost is required to achieve that torque value.

The requested torque driver is not really used.

You won't get anything extra from DME tuning to make the trans shift faster. If xHP is in drag mode then I think they already inhibit the shift torque reduction.
 
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