My exhaust used to smell fine- like normal exhaust. Ever since I had to get my injectors changed, the exhaust smells very strong, and the car has a lack of power. I remember in the past someone had said to just replace to o2 sensor, but what would be a way of testing, and figuring out why the car isn't running right?

-91 GXE maxima VG

 

You most likely have fuel leaking past a pinched injector o'ring or two..

 

who did the injector work?

black smoke at tail pipe upon startup?