fluffyninja

Quite impressed really. Looks like it's been running ok for a while without the electrode since the fracture face is the same colour as the rest of the face and the burn colour of the plug still looks pretty good. Must have been arcing directly across to the body. Guess what caused the misfire proper was the breaking of the centre electrode and it allowing gas out into the plug tube (baking and cooking the IG coil in the process )

Fortunately no signs of damage in the bore (the advantages of having access to the works endoscope) and all seems to be running ok now. Just a bit lighter in the pocket now having to buy coils and plugs at stealer prices rather than being able to get them at normal price

razzele

Whow!

How long where those plugs in there?

Wobbly

Blimey. How old were the plugs?

Edit - Beaten to it.

fluffyninja

About 18,000 miles I think it is. Had switched to iridiums so should have been good for a LOT longer. Really need to work out why it went like that. Rest of the plugs look fine at first glance but going to have a better look at them today

razzele

Yeah i thought they looked like iridium tips. I just ordered some 1 step colder Iridium NGKs for my new project! I hope that doesnt happen !

Are you switching back to platinums now?? ;>

veehexx

im sure you know, but ya might aswell just get a set and replace 'em all, rather than 1 replacement for the broken one...

im guessing just faulty/weak manufacture rather than anything more sinister!

s2konroids

for finding it though.

fluffyninja

Only plugs I could lay my hand on at zero notice were through the stealers and the standard service part is Platinums so back on them. Changed all 4 obviously. The service part is also a NGK manufacture so still on their process!

Veehexx, I wouldn't entirely rule out a manufacturing defect from NGK but I've experience of spark plug manufacturing (ok it was with Denso-Champion, Champion manufacturing on behalf of Denso to supply to their Japanese customers in Europe) and think it's pretty unlikely. It has failed at the heat affected zone of the weld though so it is possible.

I know the parts weren't dropped whilst I owned them and fitted them.
I know I was careful whilst fitting them and the plug tubes are pretty narrow so difficult to cross thread or smack it on the head during fitting.
Burn condition of the remains of the plug look pretty good so think the combustion has been reasonably normal.
Filter is fitted and intact so unlikely to be debris having got into the bore.
Plugs were mail ordered. Packaging was undamaged and no signs of damage from memory.

If I had to put down likely causes I'd put them in order:
Damaged in transit in getting to me
Something I did during fitting but damned if I know what
Manufacturing fault from NGK

Irv, The first thing I identified was the failed ignition coil. Ordered a set to replace all of them. When I changed them all over and had a chance to inspect them side by side noticed a lot of soot on the outside diameter of it. Only way that could happen was gas getting past the plug (can't have been a massive amount since it wasn't obvious when identifying the ignition coil failure). That set me to looking at the plug for a problem. Soon as I pulled it then it was obvious. Biggest problem I had identifying it was the plug was getting the bloody thing out. With the electrode coming away I could loosen the plug but was very difficult to get the socket to lift the plug out.

MB

At least it didn't break at the other end like Denso

fluffyninja

If we're talking the hex seperation from the insulator then I've spoken about that before. If it's something else not seen it so not sure what you mean