Ford Focus ST Forum banner

1 - 8 of 8 Posts

·
Super Moderator
Joined
·
9,531 Posts
Red deposits are from fuel additives being burnt (normal); why there is none on #2 I can not say for sure; possibly a lean condition from a plugged injector?
 

·
Registered
Joined
·
1,900 Posts
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
 

·
Registered
Joined
·
557 Posts
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
Just curious - why do you recommend against using anti seize?


Sent from my iPhone using Tapatalk
 

·
Super Moderator
2017 Ford Fusion Sport
Joined
·
8,194 Posts
Just curious - why do you recommend against using anti seize?


Sent from my iPhone using Tapatalk
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.
 

·
Registered
Joined
·
557 Posts
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.
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.
 

·
Registered
Joined
·
1,900 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.
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
 
1 - 8 of 8 Posts
Top