medic

so I finally got a chance to replaced my spark plugs today. I noticed when I took them out the threads and electrode were pretty black and the edge of plug where the ignition coil boot meets the spark plugs seemed like it was burnt (a brownish color). I didn't notice this on my gf's car when I changed her Mazda's NGK copper plugs after 30K.

It's been 62,923 miles since the plugs were changed for the 60K service six years ago. The dealer did that service, so I'm not sure if this is discoloration is common. I wish I had a pic to show.

My concern is that the fouled plugs may be a sign that my engine is running rich or something else. I haven't noticed a drop in milage (actually I just got 27mpg on my last tank of mostly highway mountain driving) and I still have plenty of power.

should I be fixing something else to prevent these new plugs from getting wrecked prematurely?

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iTrader: (2)

a slight brownish color is fine. i would be more worried if it was chalky white or if the ground broke off, etc, etc.

Jeff92se

iTrader: (82)

I wouldn't worry about the brown. But the tips shouldn't be black at all. Especially with all that hwy driving. How old is your 02, pcv and how is your EGR doing?

medic

Thanks guys.

Jeff, the black color was on the old plugs which had 60K on them with a mix of city and highway. I haven't checked the new plugs since it's been less than 24 hours and 15 miles since they were installed. The 27mpg was with the old plugs. The 02, pvc, and EGR are all 122K old (original) from what I can tell from the service records.

My concern was that other plugs I've seen when changing spark plugs on my gf and other friend's cars haven't been black even when they were pulled after several thousand miles. If black is normal for 60K old plugs, I won't worry.

Jeff92se

iTrader: (82)

Black all over the old plugs in not really normal. Mine at 70k, were not black.

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iTrader: (2)

lemme look around for my pictures of spark plugs and post the links... maybe the op can tell us if any of his looks like the ones in the picture?