Read my spark plugs (scary)
 

Here are my spark plugs, as far as I know they may be the originals the car came with. This is after 76,600 miles. I've premixed for about half those miles. After one look at these things I put a whole can of seafoam in the gas tank and should probably do a full de-carbon procedure. Anything else you guys can add other than change them more often you idiot?

The left side is the front leading, the middle is the rear. I don't know if the trailing ones are in order and the picture doesn't even do them justice, the edges of the electrodes are carboned up and the front leading had a quarter of it's opening gunked over.

Attachment 237061

Use Premium gas exclusively, those were damaged through detonation.

When I was running NA my plugs always looked like that.

Not quite as bad, those might have been left in a bit too long ... but they always had deposits on it like that and the same colour.

I say they look fine. Fine as in they needed to be changed but they look normal to me.

With the terminal being rusted on the the first plug, I doubt its been firing.

Wonder what the inside of your engine looks like? I'd be very intrested to see what your decarbon process can do to those plugs? And then change them afterward.

I've never seen a plug come out of a NA Renny that doesn't look like a cross between the Carbon pic and the Ash Deposits pic.

I've never seen one look like that normal picture ... FI or otherwise .. on a Renny

Zoom? You have?

nope that right. thats what mine looked like when they came out last. mine were a little more fouled and "wetter" because I had lost a couple coils just before pulling them

JesusChrist! zoom44, how many miles on those plugs??

When I changed mine I thought they looked REALLY BAD, but they look new compared to those pics!

The coil on the second plugin the right hand picture definitely wasn't firing :)

there were 30k miles on those plugs. but remember this, much of what you see on the leading plugs is from the spectacular coil failure. they would have looked more like the trailings before that happened( but probably had some build up similar to the OPs, due to the number of short trips I make).

I think I'd have demolished my engine by now if I'd been detonating, not to mention I would have heard it as well

I've already replaced these plugs with new ones and I think I've earned at least 2 mpg back if not more, I plan on doing a carbon cleaning soon and I'm definately taking a video of that one after I run a few cans of seafoam thru the gas to get the ball rolling on cleaning the engine out. I'll take a video and we might do two rx8s side by side stinking up the whole city :)

I'm pretty sure the front was still firing because I didn't notice too much of a power gain with the new plugs, there was a small exposed tip of the electrode that still allowed firing, not like zoom's horribly encrusted one in that picture though.

The leads look like part of the insulator is just cracked off and gone to me, indicating detonation; is it just the angle of the photo?

Are the internal insulators cracked?


/or is past experience clouding my vision? LOL

does anyone index their sparkplugs?
I dont know if it would actually help us but look at the discoloration difference between the different sides.
If you did index would it be best to have the L/T facing each other or both the same direction?