Truck won't shift when spraying nitrous! Stall Wall?

[MrNova]

I have an '07 Trailblazer SS AWD that shifts fine when its on motor. But when I spray nitrous it always hits the rev limiter and doesn't want to shift. Can someone please have a look at my tune and help me remedy this problem? Someone mentioned it possibly being caused by the computer going into "stall wall" from the RPM's climbing faster than the vehicle speed? List of mods are as follows:

RPM LVL 6 4L70E

Vigilante 3400 triple disc

Comp Cam 231/237 .579/.598 112 lsa

Kooks 1 3/4 LT

Stainless Works cat-less exhaust

e-fans

Volant CAI

48LB Injectors

Any help would be greatly appreciated!

[CSTune]

Can you log the event, so we can see if it is commanding the shift? The tune looks fine as far as transmission shift speed/rpm.

I'm assuming this is a 2-3 shift that is giving you issues? It's entirely possible that transmission can't contain the shift on the spray, and is just hanging out in the gear you are in until you get off the throttle. GM should have never put a 4L70 in the trailblazer ss...

Also, from what I've read, "Stall wall" is a problem of pre-97 PCM/TCM's with high stall converters. We've installed many high stall converters and don't have issues like that.

[snowvette]

Are you having the issue of the speedometer needle staying on zero during a standstill launch?

[smaynor]

Your shift tables are way out of whack! Your tune is telling the car to shift at 317 MPH, and 6400 RPM on the 1-2 shift. Also, your shift speed v/s RPM tables are not scaled correctly. If the TBSS works like a Corvette does, BOTH conditions must be met before the shift will complete. You are going to have a hard time hitting 317 MPH in 1st gear! HaHa! I have a 3400 stall in my '06 vette (A6), and it shifts just fine, but the tables are adjusted accordingly.

[CSTune]

I assume he did that because he is not using Pattern A or B, and wanted to make sure they weren't conflicting with the shift.

[smaynor]

That's possible, but I have all 3 of mine set exactly the same, and it works. It's an easy thing to try.

[Maxspeed96ct]

Im far from a pro, but One thing I would try is to copy your wot shift speeds and paste them into your 93.7% and 100% cells in the part throttle shift table . Then scale the 81.2% and 87.5 % accordingly .

One thing I cant seem to understand on the 4l70e/tbss is how the shift mph could be met when every stalled tbss ive seem , the speedo doesnt work under hard launch .

[snowvette]

The ecm still sees mph cause it still shows up in the scanner.

[Maxspeed96ct]

Gotchya , I never got to check it . It realy doesn't bother me i just wish the 1/4 mile function on the aeroforce would work it's fun to toy with and compare

[snowvette]

If you come across a MSD Dashhawk for cheap, it works on that.