Originally Posted by
Pauly
If a GM dealership made your speedo worse, this all sounds like a simple calibration issue. It sounds as if they just tried to flash your ECM/TCM with a different calibration.
Since your speedo is indicating so much faster than your actual speeed, the trans doesnt know when to upshift, therefore the engine will probably bounce off the rev limiter, unless you let off the throttle and allow the trans to upshift with a lower TPS% input.
A WOT upshift will only occur once a predetermined rpm and speed are achieved.
Do you know anyone with EFILive or HPTuners? I would think that adding an automatic segment into your calibration, then doing some tweaking to your VSS and trans tables should have you ready to rock.
Good luck man, nice car there.
peace
PAuly