Dynoing a 2011 Sierra 6.2
 

I took my truck to have it baseline dyno before i installed my supercharger.I truck kept downshifting on the dyno and the dyno guy could not get a good reading.Does anyone no how to keep the truck from downshifting.He even manually upshifted to forth gear,but as soon as he nailed it,it would downshift.If anyone has dynoed their truck, please let me know how you did it

I know my truck (4l60e) drops into 2nd below 78ish mph, so I just punch it at 80 on the dyno in 3rd. I think the nnbs computers are separate for the transmission and engine, so I am not sure what is needed to tell the trans to hold 3rd (or whatever gear is 1:1). Not sure if this helps you at all.

If your tuner cant figure that out I would find a new tuner asap! Should be able to set the down shift tables to max to keep it from downshifting.

Exactly. Holy cow - change it to do what you need, then set it back.

Yea take it to a new tuner.. That is pretty lame

That's messed up if he doesn't know that new tuner.

In for numbers when you find a new tuner

Who said the dyno guy was the tuner also? lol

manually shift it to third. bring it up to a little under 3k rpms. roll into the throttle. once past 50 mph, hammer it. it won't downshift

So where are you located? Who is your tuner? Tuner and dyno operator one in the same?