Basic info:
AEM 30-0300 x series
SpeedyEFI Stand-alone ECU
1996 Miata 1.8

I have been having an issue with Tunerstudio not reading the correct AFR and it’s no where near what the sensor in my car is reading. I wired the White signal positive from the AEM to the red/green wire on the stock harness and grounded the brown signal wire from the AEM Gauge to the chassis. when I calibrated the sensor in Tunerstudio it reads the afr as 14-15 when on the physical gauge it reads 18-19. Any suggestions on what I might have done wrong or what I could change to get it reading correctly?

Edit: I got it to work! There is a ground in the back of the head (exhaust side) that I connected it to and once I did that it was able to be read by tunerstudio!