Hi everyone, I have a 2006 g35 coupe, lowered with 19" BBS Rally Rims, My gas mileage is horrible. I'm getting about 5mpg that driving normal . My tailpipe is black, when I start the car all I can smell is strong gas/emissions . . I only have one code for air/fuel sensor which says closed circuit. I put in 3 different sensors and the all did the same thing.
Anyone have this issue ?

What specifically is the code? ECM's often blame sensors for problems the ECM software can't diagnose with the resources it has. Leaking injectors, dirty MAF's, or vacuum leaks are a few examples. One thing is certain, you'll almost never get to the bottom of a mixture issue by throwing parts at it.