spark plug pic- what is going on in this cylinder?

[clydesdale]

This is from the cylinder that is second closest to the firewall. I end up needing a new plug every 10 thousand miles. This plug has only about 8 thousand miles.

http://rides.webshots.com/photo/2966009920041641901iLccDj

http://rides.webshots.com/photo/2398256540041641901vhJXpz

http://rides.webshots.com/photo/2650458810041641901gCdQnL

[SpecM]

carbon fouling

maybe a leaky injector or intake valve stem seal?

[clydesdale]

It appears part of the insulation around the electode has disintegrated.

[AndrewBird]

That doesn't look like carbon fouling. Way to white. Looks more like pre-ignition problems.

[clydesdale]

That is what my brother said. What causes it?

[clydesdale]

Well, I have some new info. I pulled all the plugs:
#1. clean
#2. clean3
#3. white deposits and part of insulator broken
#4. just replaced, but the old one had white deposits and broken insulator
#5. replaced last year and now has white deposits
#6. clean

The plugs and wires have about 60k on them.

[bddog]

Pre ignition, cross firing- Incomplete ignition is what my book says- Your pic looks just like it

[clydesdale]

I am unsure of the cause. Any ideas?

[tn325i]

The plugs and wires have about 60k on them.

Not being a smart ass but I think you answered your own question... Plugs nor wires should be run that long..

[clydesdale]

I do not think it is just a simple plug change. One of the plugs has been changed twice during that time because the cylinder stop firing. There are 3 plugs in a row that have insulator damage, the other 3 plugs are fine.

OK, I have a minor update. I did not do the compression test yet, but I did replace all the spark plugs. The stumble is now completely gone. The car drives great. But, obviously I know the problem did not go away. So, does this change anyones potential diagnosis? I know it is not one single injector anymore, as there are 3 plugs that were screwed up. All 3 cylinders are in a row, 3,4,5. I am hoping to get a compression test this weekend or next.

[AndrewBird]

If I remember right, the injector harness is split up into 2 banks of 3 cylinders (someone correct me if I am wrong). I would check the harness for cylinders 3, 4 and 5 and see if there is anything obviously wrong like missing insulation on wires.