Background:
-1994 Miata, all stock
-MS3 with MS3X built following Frank Westfield's guide, running tune from previous owner that he said was running well on this exact car (I trust him and have no reason to doubt this)
-GM IAT sensor (confirmed working using hairdryer and looking at gauge in TunerStudio)
-AEM UEGO Wideband
-.msl and .msq files are attached

On my first Megasquirt start up, the car fired up relatively quickly. It cranked for maybe 30% longer than it does with the OEM ECU. I let it idle for about a minute and then started to drive down the driveway. About halfway down the driveway (1/4 mile, I live in the middle of nowhere), I noticed that the AFR gauge on my TS dashboard was bouncing all over the place and my AEM gauge was steady but saying that AFR was around 16.5 while driving at a steady speed. I immediately turned around and drove back up to the house. While driving back up to the house I got on the throttle a little bit and while the TS AFR gauge was still bouncing all over the place, the AEM gauge read around 13 and was steady. Once I got back into the garage, I let it idle and then revved it slightly and held the RPMs to see what AFR did. At this point I noticed that AFR on the TS gauge was showing to be about 1.5 higher than the AEM gauge.

I checked my connections and everything looks good. The sensor ground is grounded to an ECU ground, sensor power is grounded to chassis. I am not sure where to go from here and cannot find any other threads where someone had this issue (although I am sure it exists somewhere).

Any help would be greatly appreciated!

 

Was this posted before or after you entered the right voltage calibrations for the UEGO into TunerStudio?

 

Before. I made a stupid mistake and did not realize that step was necessary. All is well now. I forgot to update this thread.