Just changed the spark plugs - do the old plugs look OK? The pic below shows
top left = rear rotor, leading (plug is a 7)
top right = rear rotor, trailing (plug is a 9)
bottom left = front rotor, leading (plug is a 7)
bottom right = front rotor, trailing (plug is a 9)
Notes on the pics: the front rotor has that classic tan colour which we\'re taught is a sign of a good mixture. Is this still true for the rotary? The rear plugs are a little blacker (running slightly rich? - a good sign?)
The plug on the top right does not have a chunk missing, some of the carbon on the surface just flaked off!
And they all have a circular wear pattern, presumably where the spark has eroded the 4 outer electrodes - again, is this normal? Plugs are 3k mile old, by the way.
(The car is std (inc ecu), and run on Optimax).
Cheers!
Colour does not look bad and its best to have the rears slightly richer (cooler) than the fronts, because of the extra heat on the rear rotor
As an extra safety measure it might be worth having your injectors cleaned and flow rated, generaly you should have matching pairs - both leading the same colour as well as matching trailing. Tan brown looks about right though.
Don\'t worry Andrew there is no way I can see the colour disparity between the two Rotors being enough to worry about indeed I think the colours look good, normally you find plugs that have been running a much weaker mixture than your car when they are stock.
I would say, If it aint broke don\'t fix it .
BTW, sorry I have drawn a blank finding more spec on your car for you.