1: My girlfriend (Summer) on the boards has a 99 v6 camaro and she has been throwing a slipping tranny code for a while after her car starts to shift really hard like it has a shift kit or something??

2: At 70 mph on the interstate while in 4th gear the car acts like it shifts down with a rpm change and everything but stays in 4th gear?? I put the car in third to see the rpm at 70 which are like 3700 and then went 70 in 4th and waited for the change and sure enough it jumps about 300 rpms from 2800 to like 3200 while in 4th gear? but NO downshift?? its weirding me out HAHA anybody else have this problem before?

 

It sounds like there is a check ball sticking in seperator plate. I believe you need a new seperator plate with torlon *****. The next time it happens at 70mph keep your foot steady on the gas and lightly apply the breaks. If the chugging goes away, what I just told you needs to be replaced. Good luck, Vince.

 

ok, thanks.. what you mean by chugging is the rpm change right?

 

fwiw i had the same exact problem.in my case it ended up being my converter going bad(stock one). it would start to slip and the pcm would add line pressure which made it shift very hard.on the highway it would slip in and out of lock-up on it's own.when it started shifting hard i could pull over,turn the car off and count to 10 and it would go back to normal.hope this helps.i have a stock verter if you end up needing 1.good luck

 

Converter unlocking as previously posted.