Hello all, worked on a 2011 CTS-V tonight. I spent all night working on the trans tuning. The car has a built 6L90E with parts from transmissioncenter.net with their pressure tuning. I will contact them Monday if no one has any ideas on this. Stock converter. We rebuilt it last year after repeated 6-second 1/8th mile passes when it started slipping. The owner sent the tune to them, they changed it for their parts, and all I have modified until tonight has been the shift speed/rpm stuff. The car did flawless last year, and we ran several 6.8 passes.
Now, we put in an LSX376 crate engine. The car is roughly 900 HP now. It will not shift out of first without hitting the rev limiter to save its life. It has 18" drag radials now instead of the 19" ones, but I compensated for that. I have been using the spreadsheet to adjust, but even lowering it down to 1500 RPM and 5 mph, it will not shift. We started out much higher, but just to get a response continued lowering it to no avail. We set the rev limiter to 7000 RPM, and it still hit it. The car runs through the gears in the burn out, getting into 4th even. There is no slip and a nice linear pull on the graphs, it just does not shift. 2nd will occassionally go into the rev limiter, but it was cooling down and the car was making more power, so I was having to pre-empt the shift more.
I logged gear, it shows the gear changes at the commanded mph, but the indicator on the dash shows when it actually shifts, which is what the data log shows).
Any advice is greatly appreciated. I've been able to work through most issues, but this one I couldn't get a response regardless of what I tried.