Built 4L60e issues, help needed

[Fleshe]

Hello,

I've got a fairly decent 4L60e build that I'm starting to have some issues with and I'm hoping to get some guidance with my issue from the combined intelligence on this forum.

Build List

2007 Chevy Tahoe, 5.3L Gen 4 Iron Block, BTR Stage 4 Cam, Long Tube headers, Coated Pistons, CAI
E38 PCM / T42 TCM

Engine Dyno tuned to 330 HP NA

Corvette 2nd Gear Servo
Beast Sunshell
Billet 10 Vane Pump Rotor
Sonnax Boost Valve
Billet 4th Gear Servo
TransGo Performance Separator Plate
Circle-D HP 278MM 3200s Converter
Derale 15800 Electra-Cool Cooler
Heavy Duty 3-4 Clutch Pack
Anchor 2638 Transmission Mount

My issues started last week and the build has only been running for about a month now behind a 330 HP dyno tuned N/A 5.3 Gen 4 motor. The transmission has been tuned using BlueCats Tuning tool for HPTuners that is offered over at the HPTuners forums.

When the transmission is cold, I put it into (D) and all is well under part throttle until it tries to shift into 2nd gear. During the shift there is a loud and violent bang followed by my RPMs shooting up like the transmission shifted into neutral. As the vehicle coast forward and the RPMs fall back down there is another bang like the transmission threw itself back into 1st and then it's like the transmission is permanently in neutral while the shift selector is in the (D) position. At this point (D) does nothing, if I manually put it into 1st gear, the car moves forward just fine and I can manually shift all the way to 3rd just fine. While in 3rd gear the transmission will not go into lock up and if I shift into (D) to hopefully go into 4th aka OD, it acts like its in neutral.

Now, here's the weird part. If I drive around in 3rd for about 5-10 minutes, it i will eventually go into overdrive and I can put the truck back into (D) and it will shift just fine on its own through all the gears and even lock the converted like there is nothing wrong. It will operate just fine until I let it sit long enough for the transmission to cool down and then it starts this entire process all over again.

What are your thoughts?

Things I've tried

1. Flushed transmission fluid and put in all new fluid (the old fluid was discolored but not toasted by any means)
2. Check shift cable to make sure it was in the proper position (all looks good)
3. Reloaded the Tuned TCM calibrations and even put the factory calibrations back in. (Both do the same)

I'm at a loss and so is my transmission builder. At this point I think I may have a bad TCM.

 

[Kraig]

Fluid was discolored after a month? How many miles?

 

[esoteric_ast]

Could something have been left loose in the tranny? This could block fluid from reaching correct pressure to actuate items.

 

[thompsoj22]

Has your builder done line pressure checks? It really should be a simple diagnosis with such a dramatic problem. Ill "guess" it is in the valvebody, programming plate, checkballs, hung up solenoid valve. Either way dont keep driving it.