So the deal is, my car is running lean. i thought it was my o2 sensor, because the check engine light came on. So i replaced the o2 sensor with a factory one. Next, i connected my air/fuel meter wire at the ecu, instead at the white wire on the 02 sensor because tuners were telling me that the o2 sensor could get messed up if the wire is exposed. My motor doesn't have any crazy setup or anything, and i don't know why it is running lean. it runs so lean that when i pull in my garage and pop my hood, it smokes. could it be the fuel filter?

 

-dirty fuel filter
-clogged injectors
-improper ecu