Hello, I have been using the AEM UEGO on my 1995 Miata for about 2 and a half years. I originally just had it installed on the stock naturally aspirated engine so I can learn to tune with MSPNP2. Fast forward to 5 days ago... I just installed a fully forged 1.8l BP with a .5 over bore and turbo.

Issue: After the first few drives I noticed the wideband sensor stopped working correctly. It would read properly for around 3 to 5 minutes before slowly leaning all the way out and staying like that permanently. I improved my grounds, triple checked calibrations on tunerstudio, and replaced the 02 sensor (3 times now). I understand that the 02 sensor is really close to the turbo, and needs to moved further downstream. But is that the only issue? I am very confident it is also on the right mode as well (AEM UEGO has a few modes. I am using mode "P0")

Question: What are things I should look for or check to fix my issue? Can the gauge itself fail over time? Is it grounded wrong? Is it just the location of the sensor being so close to the turbo? Am I just big dumb?


Random added info: I have the wideband grounded to the same spot that the engine ground strap is connected to.... on the little lip or shelf under the heater core hoses (left hand drive)

 

I had the same thing happen with mine but it was fixed by replacing the O2 sensor. Did you use a Bosch brand sensor? Mine also failed shortly after swapping in a turbo 1.8 when it was fine for over a year on the stock 1.6. It died right after I pressure washed the engine bay without covering the air filter so I think that's what did it, apparently the sensors can be killed by water in the exhaust. If nothing else works try moving the sensor further away from the turbo.