hi Scotty, My 2004 hyundai Elantra has 200K miles i bouth used... I have noticed that the #4 sparkplug is fool of black soot, I have swapped injectors, the #4 to the #2 position also swapped the coil trans formers and still the #4 is theone getting full of soot. Ideas?? Thank you

odds are engine is worn inside there, do a wet and dry compression test to find out if that's the case, then get rid of it or rebuild the engine if it is

this would affect MPGs and oil cinsuption I guess because it has that to,
I remmeber doing that weet dry test I while ago,after noticing th espark plug issue,
And I dont remmenber the numbers but they where all very close to each other with in 5 psi.