Just now when i started my car the exhaust was black, and the tip always has black remains. Anyone with similar problems?

 

It could be a couple things:

1. Oil can seep past rings and seals into the cumbustion chamber when the car sits. Then at start up, the residual oil is burned out.

2. You could be running rich. That could be a contribution of the mods you have (not sure if you have any).

My old civic always had black residue on the tip. It had lots of mods, but generally speaking VTEC motors run rich in VTEC range. Its a safegaurd. I would assume Nissan motors to be similar if you drive the car hard.

 

black smoke means you are probably running rich.... smoke from burning oil has a bluish tint to it....