Timing drops to almost nothing when trying to brake torque and launch??

[revrentzero]

I recently finished my project its a 2001 gmc sierra 1500 4x4 with a 5.3, 4l80e, single 7875. torque converter is a circle d pro series 3200 stall. the issue im having is when i went out and did some driving and datalogging i tried doing a 4x4 launch but as the rpms started to rise and boost got to around 5-6psi timing was dropping off almost to nothing, rpm got to around 2700rpm and wouldnt go higher and when i let off the brake it was an absolute slouch. i didn't really stay in it long enough for the timing to get back up and start pulling hard. what could cause this? Normal driving and wot pulls the truck runs perfect. ill put my tune and datalog in maybe its something obvious idk. Thanks for any help!
BrakeBoost.hplTahoe Flex os, 80e segment swap Cureent tune.hpt

[5FDP]

Set the brake torque mngt from 1 to zero under the systems options.

Then set the abuse mode to 7,000rpm and 0 mph in the engines torque mngt tab. You can also max out the max torque vs rpm to 640 as well.

[revrentzero]

when you say under system options i dont understand that? i did change the abuse mode but dont get what you mean for the brake tq management, sorry im still learning lol

[5FDP]

Click the systems tab, then the systems options tab.

[revrentzero]

Oh okay i see it now, i changed that and when i take the truck out tomorrow ill try it out and see how it does. Thank you sir

[anniversaryss]

9 time out of 10 stalling on the brakes is always Brake torque management

[revrentzero]

it was brake tq mngt, it launches pretty good now thank you guys so much!