Dead spot in WOT pull

[Lahmer_52]

I've been having issues with what seems to be a dead spot in acceleration on WOT. if you look at the attached log at about 16:38:41 acceleration just levels off but afr/spark seem to be fine, it does the same thing but actaully dips in RPM at 16:38:45 at around 5700 RPM. The engine is a 6.0 based 408 with 246in 252ex .620 lift cam, LS6 intake with 42 pound injectors and ported 243 heads. The car did something similar when it had a LS9 cammed 5.3 in it but was less noticeable due to a lot slower acceleration. Behind the motor is a 4L80e with a shift kit. Wondering if there could be something with the transmission causing it as i dont see where the engine tune would be influencing this flat spot? Any help would be greatly appreciated!

[shtboxyj]

maf needs to fail on 1st error in dtc. and while your still WOT right at the end it goes 19. lean

[Donny O.]

looks to me like the torque converter is trying to go into lock up. try changing converter lockup speed at 100% throttle to some rediculous number so it doesn't lock and see if it changes. you can see it unlock when you floor it. downshifts and rpm jump to 4200ish and hang for a split second then jump to 4700ish when it unlocks. I could be wrong but thats what it looks like to me with the info I have

[Donny O.]

and actually if your talking about the first time you floored it it seems the tires broke loose shifting to second and was gaining traction again so the speed stayed the same for a bit as the car was catching up to the tires. the second time flooring it in the log is what I was referring to in my first reply. but even in the first WOT after it shifts you can see the rpm drop a little....then drop again as the TCC locks. its set to lock at 47mph in 2nd gear. again I could be wrong but its easy to change and see if it makes a difference.