What will be better, going by the factory readings or off my aem uego?

 

Better? Depends on what you are trying to do and where you have the AEM sensor mounted in the exhaust stream.

 

I guess i ment more accurate, my aem is mounted in the 2nd o2 bung, and its readings seems to be pretty off from the stock sensor, example,, it shows a 15.8 when stock says 14.3 car smells rich so im guessing stock is correct

 

Well if your stock sensor is working right (they typically slowly die and become inaccurate over time) it is very accurate and they should be close. I have sensors in the same locations, except a PLX setup in the secondary O2 location and they read very close to each other. Except the PLX has a wider range on the low end.

14.3 is not rich, but the the stock tune does run rich in areas. That said, I have heard of numerous problems with the AEM wideband.

 

I think it's the aem. It's off by around .6:1 at times. I probably will get a new oem one due to high mileage though