ctandc72
Well-Known Member
Actually the SCT Tuner does nothing for speedometer / gearing changes for the S550. That value is not in the ECU (which is what tuner deals with) it's stored in the BCM (FORScan programming).Yes. I have taller tires than stock and shorter gears so I used the SCT Tuner to update both values and flashed the car. I have confirmed with the GPS app on my phone that the speedo is correct. If you have an auto that process is much more complicated.
But changing from 3.15 to 3.55 requires NO changes. I GPS Verified my speedo after installing 3.55 gears with NO changes whatsoever and the speedo was dead on. The ABS wheel sensors actual deal with detecting speed / wheel rotation.
Sponsored