Another black/oily #6 plug. Anyone figured out why it happens?

[onebadmofo]

Leaking valve cover gasket? Why would the plug be black though?
Changed my sparks today, those had around 15k on them.
Car ran fine, I'm not losing any oil. In fact I'll be due for 7k oil change soon and I still have 1/4 of original oil left in the iDrive thingie Changed sparks only because I had plugs sitting in closet for months and was bored.

[mdog]

Based on some other stuff I've seen that looks like what they call blow by. I'm not an engine builder or machinist though. Little extra oil getting burnt up in the chamber. May not be enough to matter. Is this the first set that has looked like that?

[rudypoochris]

Probably valve cover gasket... I can't imagine what else it would be. Although the discoloration on #6 insulator could maybe be fuel.

[orange]

Could be leaky injector.

[Eleventeen]

I'd be interested to see a collection of misfires from various cars to see if cylinder 6 was the most common. Maybe correlate that data with carbon build up on each intake valve, injector failures for each cylinder, etc.

Without any of that data, my guess would be that maybe cylinder 6 runs rich (possibly due to intake manifold design)? Or maybe it runs much cooler?

From what I remember, I'm pretty sure my #6 plug always looks like that too.

[leo985i]

When I changed my spark plugs, about 4k miles ago, I noticed that spark plug 3 or 4 had a little oil on the top of it, and there was also oil on one of the holes on top, but not much. Haven't giving it much thought since my car seems to be burning oil normally and runs fine. Might have a leaky gasket, but so far no problems, or running low on oil

[lulz_m3]

I vote leaky injector in cyl 6

[Itsbrokeagain]

You will not get oil from the cylinder that far up the plug. You have a leaky valve cover gasket grommet or two...

[rudypoochris]

You will not get oil from the cylinder that far up the plug. You have a leaky valve cover gasket grommet or two...

Exactly. Also it is oil at the top of the threads not the bottom on the first plug. It isn't blow by and blow by isn't possible there. Suspect gasket and also check PCV system to make sure it is venting fine.

[lulz_m3]

You will not get oil from the cylinder that far up the plug. You have a leaky valve cover gasket grommet or two...

Tip looks pretty $#@!ty, on Cyl 6. Whats your thoughts on that?

[Itsbrokeagain]

Tip looks pretty $#@!ty, on Cyl 6. Whats your thoughts on that?

done a valve cleaning recently? Could have poor airflow into the cylinder, causing a rich condition, or you have an injector nozzle that is crudded up and spraying poorly...hence replacement.

[rudypoochris]

I wouldn't be entirely surprised if it was a valve cover gasket and an injector.

[onebadmofo]

I have a spare injector, gonna replace it and see what happens.

[themyst]

Valve cover gasket 100%

[ChuckD05]

myst always says valve cover gasket and i always say injector , lol

my 135 had cyl 6 look like that bmw changed my injector never came back

[LQQKOUT]

A new injector will fix your problem. I had the same issue.

[rudypoochris]

The first cylinder cant be an injector...

[mdog]

So can the injector be tested by moving it to cylinder 3 or 4 for example and seeing what that looks like after a few thousand miles? If it were mine I'd try that before throwing a part at it. Seeing that you have a spare injector though I suppose you might as well swap it out.
You are using a met kit correct? Is this something common from that cylinder when using meth? Makes me wonder about theoretical stuff with atomization and intake flow when using meth. Maybe getting an unequal volume to that cylinder or something? Probably nothing that complex. Hope the injector takes care of it.

[onebadmofo]

Meth is used, valve cleaning was done about 10k miles ago.

[onebadmofo]

I also should mention that I have trouble starting the car sometimes. It cranks but doesn't start. I would get out, lock the car, unlock it and it start right away. LPFP isn't holding the pressure? Both HPFP and LPFP were changed recently. Also could be the tune? I have the contraption that goes in the second hole on the fuel tank (fuel pressure regulator) sitting in the closet, gonna replace it one of those days.
Once the car is up and running I have no fuel issues whatsoever and it's pushing down 470rwhp easy.

[mdog]

Sounds like a blast to drive. If it were mine I wouldn't be too worried about it, especially seeing how you're not burning much oil at all if any. Swap out the injector like you said and just check it at oil changes or every 5k miles.

[LQQKOUT]

The first cylinder cant be an injector...

I'm talking about #6, being a bad injector.

[rudypoochris]

I'm talking about #6, being a bad injector.

Could be, but that doesn't explain the oil on spark plug 1.

[rwalker]

For those suggesting valve cover gasket: can you explain how oil from above the spark plug hole (where the gasket in lives) finds its way into the combustion chamber (where the tip of the plug lives)?

[Itsbrokeagain]

I also should mention that I have trouble starting the car sometimes. It cranks but doesn't start. I would get out, lock the car, unlock it and it start right away. LPFP isn't holding the pressure? Both HPFP and LPFP were changed recently. Also could be the tune? I have the contraption that goes in the second hole on the fuel tank (fuel pressure regulator) sitting in the closet, gonna replace it one of those days.
Once the car is up and running I have no fuel issues whatsoever and it's pushing down 470rwhp easy.

if you are having problems starting it is most definitely an injector heading south..its dribbling into the cylinder overnight, causing a hard start in the morning.

so moral of story. change injector and valve cover gasket