kpennepacker

Posted in pcm tuning but no hits so ill try here. I did my sonoma swap using an fbody harness and computer and an f body ls1 4l60e. I have an 8.8 with 4:30 gears. My buddy tuned my truck and changed tire size and gear ratio but speedo is off both on hptuners gauge pull down and my speedo. Both match but are off by about 30 mph. 40ppr vss and everything seems good in program. Any ideas is it the sonoma bcm

rpturbo

iTrader: (47)

What year bro? If you can't find an answer here, try s10 forum. I know mine works fine in my 94.

ls1nova71

iTrader: (4)

Sounds like your math may just be off. If HPTuners and your speedo are showing the same info, then when your tuner set the gear ratio and/or tire size, he was off a bit.