Just changed plugs. These have a few thousand miles on them. What do you think?

The plugs are in their relative locations as they would be installed on the car.



Thanks for your input.

 

need a way closer view with good lighting (and not blinding light from a camera flash). Normally when you check plugs (especially on regular plugs with a grounding strap) you use a magnifying glass.

 

I cannot see them either,but they look very dark.These came out of my RX8 after about 13k miles

 

Looking at the plugs, I'd say the car is running a bit on the rich side..especially if that's is only after a few thousand miles like you say. What type of driving do are you doing? Interstate, city, 5 miles and shutting it off type thing?

A milky brown half with it getting darker on the plug is what used to be the norm before we started getting better info with the various widebands.

A better picture would help as well.

Tim

 

Yeah, apologies for the pic. My photography skills suck. I'll try to take something better.

Plugs have 3 track weekends, 4 autox events and maybe 3,000 street miles. Street usage is usually spirited ~20 mile trips. Sometimes I take it on short trips out to lunch and such but usually longer trips.

The electrode in the middle looks very good so its really just the accumulated black crap on there. I also premix 1 oz per gallon since the OMP isn't working.

 

Too rich (prior to being pulled). Look at six rotor's plugs above: Tannish bone color to the milky brown would be about right. (That's what I'm getting on mine.)

 

Be careful to realize that fuel additives can alter color!

 

what are you using for tuning/engine management? It could be the premix (not sure how much that affects it), but the consistent black color all over the plugs indicates to me that you are too rich under most conditions (both low load cruising and high load, as opposed to just rich under boost). Normally (on non BUR rotary plugs) the outer ring is indicative of overall mixture and the inner part with the electrode and insulator will tell you if you may be detonating or have a plug that's too hot/cold. But even then, on race cars usually they pull new plugs right after a dyno run for the most accurate reading.

My B10EIX plugs (which have a ground strap like a piston engine's plugs) are a light brown/tan color, but I have carefully tuned cruising AFR's into the 14's and 15's on my Power FC.

 

Soot from richness.

 

Rich or lean where in the rpm band and at what throttle setting? You cannot deduce anything about a/f ratio from spark plugs unless you perform a plug chop, and that can only be done after running at full throttle for an extended period of time (then killing the ignition). Any idling or even partial throttle will not only discolor the plugs enough to make any type of reading basically useless, but the intake fluctuations that occur during partial throttle create havoc with a/f ratios; this is why port-timed intake engines like the rotary need to run a little on the rich side at partial throttle in order to run properly. Any attempt to lean ratios out to a level considered "normal" results in misfiring because of the intake fluctuations.