today i changed my oil, oil filter and spark plugs. i started my car up and let it warm up for about 5 minutes. i turned it off then checked my oil. then i started my car up again and revved the motor to 7000 rpm's. when i did that black stuff came out of my exhaust. does anyone know what that could be? or what i could do to make it stop.

 

carbon build up possibly left over form the bad old plugs not burning all the gas?

 

yeah, thats probably all it was. Black isnt as bad as blue or white! It might be a touch rich as well. Just keep an eye on it on startup