Why does my Cyl 2 spark plug look like this?
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Plug #2 was replaced separately from the other three.
The red deposits are from MMT (Torco and others), a good octane boost. Note that plugs 1, 3 and 4 have anti-sieze on the threads whereas #2's threads are clean.
If it were me, I'd replace all four plugs with one step colder NGKs (6510), gapped down to 0.026" - 0.028" and then retest. Please don't put any anti-sieze on the threads, but maybe a (very) little dielectric silicone grease in the rubber coil extenders. It's hard to tell from the picture, because the brightness is so high, but I can't readily make out the annealing line on the ground straps. The insulator on #2 does look so white it looks lean, but the top ceramic on all the plugs is also incredibly white so hard to say.
Once you have a set of known good uniform plugs in the car you will be in better shape to do a few pulls and then do a fresh plug read. If you are worried, fill up with 93 and pick a 91 map to give yourself some headroom.
Hope that helps,
Mark
The red deposits are from MMT (Torco and others), a good octane boost. Note that plugs 1, 3 and 4 have anti-sieze on the threads whereas #2's threads are clean.
If it were me, I'd replace all four plugs with one step colder NGKs (6510), gapped down to 0.026" - 0.028" and then retest. Please don't put any anti-sieze on the threads, but maybe a (very) little dielectric silicone grease in the rubber coil extenders. It's hard to tell from the picture, because the brightness is so high, but I can't readily make out the annealing line on the ground straps. The insulator on #2 does look so white it looks lean, but the top ceramic on all the plugs is also incredibly white so hard to say.
Once you have a set of known good uniform plugs in the car you will be in better shape to do a few pulls and then do a fresh plug read. If you are worried, fill up with 93 and pick a 91 map to give yourself some headroom.
Hope that helps,
Mark
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557 Posts
Just curious - why do you recommend against using anti seize?
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Honestly most advise against it including the maker of the plugs themselves. If you do choose to use it, that's usually fine, but should be used very little.
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557 Posts
Did a little research because I had to know "why". In short, if the threads are plated (nickel, usually), then anti-seize is not necessary. Lots of "I always use it", and "I never use it" arguments, but the plating is the determining factor.
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Yes, plating (and NGK is very specific about this) eliminates the need for anti-sieze, but also don't forget about over-torquing risk. Anti-sieze is has higher coefficients of friction than plating, so if you torque down a plug with anti-sieze on the threads to the same in-lbs as a plug without, the anti-siezed plug will be over-torqued.
Having said that, what I do when I regap plugs is to use a microfibre towel on the threads with a little detail spray, interior cleaner or other mild degreaser, to remove the carbon buildup on the threads - again, to avoid under-torquing the plugs when I put them back in (carbon deposits are not slippery at all...).
It may be overkill I know...
All the best,
Mark
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13,883 Posts
I believe certain spark plug manufacturers day don't use it because it leads to over tightening of the plugs. Those ones usually put a different plating to prevent seizing.
Sent from another garage.
Sent from another garage.
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