One sparkplug much dirtier than others

suspecttv, Aug 28, 12:40pm
Hey folks,

My wife's car was idling and driving extremely rough, sounded like it was about to stall when parked up at lights etc. So I gave it a new set of sparkplugs and that fixed it up.

All the spark plugs were old and showed usual blackened ends. however one was much more burnt than the rest. It was blackened up into the white ceramic part and a little bit oily as well. Does anyone know possible causes for this, and if it's worth getting checked out!

'97 1.5L Mazda Familia Sedan

Cheers!

mugenb20b, Oct 2, 4:04am
Probably slightly down on compression on that cylinder, Sometimes engine flush + oil change can make a big difference.