Range is from 10-19.7 instead of 10-20 AFR

Hi! I’m using my Spartan 2 controller with a Speeduino and I’m using the following parameters that are the default for “14point7” in the “Calibrate AFR Table” in Tuner Studio

Point 1 1V 9.7 AFR
Point 2 4V 18.7 AFR

Should I be using different settings?

It seems like it works best at 0V = 10AFR, 5V = 20.2 AFR
There’s a conversion spreadsheet and calibration guide on the 14point7 website, but when I used it the numbers weren’t lining up. (It was shooting for 13.3 and 16.7 on startup, but when I used the spreadsheet it was always giving me 13.1 and 13.4 as the first number on startup.)