I am new to LS1's & just got my car back two days ago & was doing a little testing on the service road here where I live in Kaufman since I have never owned a automatic.

While trying to find the sweet spot on the RPMS from a dead stop to launch the car at & what PSI on my ET Streets to get it to hook, The transmisson at a WOT hit from a dead stop would not shift in to 2nd gear, It sounded like it was banging on the Rev limiter, So I tried it from a 50 punch & the same thing again that time I was in 3rd gear at 50 mph & punched it & right away when it tried to kick down to 2nd gear, DA DA DA DA DA DA DA, It sounded like it was just bouncing off the Rev Limiter. (WHICH IT WAS BOUNCING OF THE REV LIMITER BECAUSE IT WAS NOT SHIFTING IN TO ANY GEAR FROM A WOT HIT)

So I took the car home, On the way home I just drove the car normal. Well from a dead stop the car went in to second gear but it was shifting in to 2nd gear at 5000 rpms, The same on the 2nd to 3rd gear shift!

Any Idea's what is wrong with my trans?

 

First step is the check the fluid level.

 

Fluid level is good & the color is good, Pink Red from the looks!

So any idea's, Is my trans shot?

 

It really sounds like it. Take it to a trans shop and get their opinion.