Im tinkering on my friends 2000 firebird. i installed the performance tune from predator, we have added 3.73 geras ,stat. lid, exhaust. Everrything hauls *** .BUT at 50mph it will not downshift to second. Its the 1-2 2-3 3-4 settings that I need to adjust. But what do I need to make it downshift?
From a dead stop at WOT it shifts into 3rd at 75 so something inst right.

 

I'm not sure if this has anything to do with it - but how did you recal the speedo? Did you use the factory/actual tire sizes for the 3.73's?

www.runninwiththedevil.com/faq.htm

 

On the predator you tell them what gears you have, tire size etc.

 

When I programmed my car for 3.42's (originally had 2.73) I didn't select gears at all, just used the chart, then checked it against the calculator at www.f-body.org/gears/ Maybe my version is different.