DCT shifting characteristics

[NotABimmer]

So I have an E90 M3 DCT in my Camaro behind a stroked 416ci LS3. It is controlled by MaxxECU with the factory TCU in the trans. I'm getting some weird shifting characteristics on downshifts when on the throttle both in auto or manual mode. There's about a 2 second delay from when i hit the downshift paddle to when it completes the shift, which can be seen in the ECU logs. The shift appears to happen pretty quickly, but the clutch handoff from one to the other takes 2 seconds to happen. This mostly happens when i am lugging the car between 1500-3000rpms and on the throttle (from anywhere between approximately 2%-100% throttle). If i'm higher in the RPMs it appears to shift relatively ok. If i'm off the throttle, it's pretty instantaneous. I do have slightly modified TCU firmware to change my differential gear ratio and increase clutch line pressures. This seems to happen in any drivelogic mode.
Does anyone know why it could be doing this? I understand that it might be hard to or impossible to answer since it's not in a BMW anymore, but i am grasping at straws here. Any help would be greatly appreciated.

[amrazM]

whats the line pressure inside the transmission when youre trying to complete the gearshift?

what is the target line pressure vs the actual?

[drwankel]

I had this same phenomenon happen to me intermittently when I had a leak on the DCT. Likely caused by low fluid level.

I could usually snap it out of it by going from manual mode to automatic mode and then back, but not always.

Once I had the leak fixed and did a full DCT service (new fluid and filters) it never returned.

[NotABimmer]

Originally Posted by amrazM

whats the line pressure inside the transmission when youre trying to complete the gearshift?

what is the target line pressure vs the actual?

The pressure is right about 250psi (17.2bar) before the shift, then it drops down to 213psi (14.7 bar) a couple times during the shift. as soon as the dct shift status changes from downshift to not engaged, it spikes to about 287psi (19.8 bar) immediately after the clutch hand-off from one to the other, then it drops back down to 250psi. Unfortunately it does not tell me the target line pressure as far as i can tell.

I am unsure if the dct shift status being active means that it is physically trying to shift the transmission or if it would still be active until the clutch hand-off is completed regardless if the transmission was in gear before that point or not.

[NotABimmer]

Originally Posted by drwankel

I had this same phenomenon happen to me intermittently when I had a leak on the DCT. Likely caused by low fluid level.

I could usually snap it out of it by going from manual mode to automatic mode and then back, but not always.

Once I had the leak fixed and did a full DCT service (new fluid and filters) it never returned.

this is a new install and it isn't intermittent. It has new fluid and filters and it was filled properly and checked again for safe measure. trust me, i wish it was that simple lol.