Which is more critical, Trans Rev/Mile or VSS PPM, with Aftermarket Speedo?
08-17-2023, 09:45 PM
#1
Which is more critical, Trans Rev/Mile or VSS PPM, with Aftermarket Speedo? I have a programmable Speed Hut speedometer that uses the PPM and is calculated by driving 2 miles and it learns on its own. My MPH readings are off 3 mph while datalogging vs GPS and my Speedo. I need to get that lowered down but also; I noticed my original tune used the wrong number of VSS teeth (45 instead of 40). I know they are both used but the VSS PPM is mainly for the Speedo. Can you adjust one and not the other, or do you need to apply a certain percentage of change to both?
2000 4L60E with 25.66 tires and 3.73 gears and 40 tooth VSS gear
2000 4L60E with 25.66 tires and 3.73 gears and 40 tooth VSS gear
09-14-2023, 01:47 AM
#2
If you adjust one the other will have to change if you want to keep the same output. Just fine tune your pulses/mile until the mph is correct between GPS data and a scantool. Than calibrate your speedo