A&Q about 350Z
Q:
ok pulled the plugs today and they are all BLACK i know that the sparkplugs can tell u how ur engine is running but how? what does black black black mean? too rich? too lean?
A:
To much lots of bad things.
Black is a classic sign its running to rich, or its running to cold a plug, or the timing is to retarded, or any combination of all 3.