2013 GT speedo will not calibrate with custom tune- help!!!!


New Member
Mar 4, 2019
Need some serious help with this one. 2013 gt, speedo will not calibrate no matter what gear ratio or tire rev rate setting. Was completely fine on the tunes that came from SCT on a livewire ts I had. Returned ecm to stock before winter and installed a used vmp supercharger that came with a SCT X4. Went with a custom tune for the blower and speedo has been off since the new tune with the X4 and wont adjust. it is way off 18mph under at 70mph and the traction control started having issues because of the wrong speed to throttle pedal relation, no cruise control in 5th or 6th gear which is normal for ratios being off, and the list goes on. now that being said neither SCT or my tuner can figure out why my ecm will not take parameter changes to only the speedo. SCT says they have never seen it before, did the custom tune brick my ecm? I have a factory 3:73 MT-82 car, and have even went with extreme setting from a 2:55 all the way to a 5:10 gear ratio setting, it does not change the speedo by even a tenth of a MPH. I have even had the battery unplugged overnight, returned to stock countless times, multiple new tunes were sent to me where i could adjust the settings myself, you name it, it wont work. Im stuck with a expensive brick at this point... please help
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