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!

 

Hey, currently having kinda like the same problem, can you show me where did u ground it to? I wired mine to the old o2 connector which should be the blue wire and then grounded it to the connection right below the brake booster but it’s still doing the same. (I’m running a speedyefi)

 

Black wideband - black/blue line
Red wideband - blue/red line
Leave black/yellow and red/white alone
This is how mine is wired and it’s working good. Did you calibrate it in the tunerstudio settings?

 

Yeah I calibrated it with the voltages and stuff, and the cables, did you do it to the O2 Female or Male? I’m doing it to the male and I’m too scared to cut the stock wire harness lol, but my AEM has a Black and red wire for the actual power on the gauge, then a white wire for the +0.5v output signal and a brown wire for ground or negative signal