s550 Anti-Clunk Torque source

[Jn2]

So I ran into this today while tuning a customer, the car pulls like a train through all gears how ever on the 4th to 5th gear transition timing is pulled back to almost 0* of advance and the TB closes and wont open, if you leave the foot on the floor it will conitnue pulling, but the throttle is shut for about a second which kills all the momentum the car had....

Throttle Source = Torque Reduc < Driver Demand
Driver Demand Limit Source = AntiClunk tip in TQ Limit
Torque Source = Tip in Limit

I tried tuning off all the torque management switches for the trans and maxed out torque limits for trans as well, none of this seems to have remedied the issue, and it only happened on that 4th to 5th gear change.

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[murfie]

The spark will drop like that from going into DFCO from the throttle being closed.

It seems like it didn't apply the throttle until the gear was engaged if you look at where RPM drops. The RPMs look to be hanging so I would guess A is bleeding slow. You would have to log your trans solenoid pressures to see what solenoid is taking the time. Building pressure in B is opposed by D in its regulator. bleeding pressure from A starts happening and allows B gets its valve positioned. Once B and D match pressures the clutch is applied. Lowering the off going 4-5 pressure can speed up the shift if A is bleeding slow and dragging the RPM's. If you are not getting flare after B and D match you can lower the oncoming to speed it up more.

[Jn2]

The spark will drop like that from going into DFCO from the throttle being closed.

It seems like it didn't apply the throttle until the gear was engaged if you look at where RPM drops. The RPMs look to be hanging so I would guess A is bleeding slow. You would have to log your trans solenoid pressures to see what solenoid is taking the time. Building pressure in B is opposed by D in its regulator. bleeding pressure from A starts happening and allows B gets its valve positioned. Once B and D match pressures the clutch is applied. Lowering the off going 4-5 pressure can speed up the shift if A is bleeding slow and dragging the RPM's. If you are not getting flare after B and D match you can lower the oncoming to speed it up more.

Awesome, I'll log those and see what they look like, what's funny is the 4th to 5th gear engagement literally feels like the one you would make on a MT82 when you baby into 5th during WOT pulls...

[Jn2]

Thanks Murfie, was totally a shift pressure issue...car pulls hard and shifts into 5th with out issues, had to dial back the pressure a little bit and on the upshift offgoing table for 4>5 as well.