That could be your problem there, those plugs are too cold for you. They are probably fouling out.
that was mainly what I am coming up with but still doesn't explain the noise coming from under my car. ( the grinding noise )...but maybe the fouled plugs have caused fuel to get into my catalyist conveter, therefore plugging it as well!
2011 Honda Civic EX-L - Leather/Sunroof/LOADED!
2009 Saturn Aura XE - I got shift paddles!!!
'98 Olds Cutlass - Good, Dependable
'06 GP GT S/C - Traded it in