Dyno tuning the ECM in a 2018 GMC truck with 8L90 transmission. TCM is still locked with factory tune. Trying to command sixth gear on the dyno using the VCM Scanner special functions. It works perfectly about 10% of the time. The other 90% of the time, the button lights up but the transmission remains in 7th or 8th gear. Am I missing something obvious here? Thanks in advance.
2022 Cadillac CT5-V Blackwing (733 whp)
2022 Cadillac CT4-V Blackwing (716 whp), 10.750 @ 134.77 mph
2016 Cadillac ATS-Vs (eleven ATS-Vs in the 9s)
2008 Pontiac G8 (first G8 in the 10s), 10.727 @ 129.87 mph
2000 Bonneville SSEi (first 3800 Bonneville in the 10s), 10.711 @ 125.71 mph
1999 Grand Prix GT (first 3800 FWD in the 8s), 8.902 @ 154.90 mph
1998 Firebird (first 3800 RWD in the 8s), 843 whp, 8.991 @ 152.12 mph
1998 Grand Prix GTP (first 3800 FWD in the 10s), 9.499 @ 145.13 mph
Reply With Quote