loud tick, oil on spark plug

[trayday]

About 10k miles ago i had a misfire on cylinder 8, dealer said it was the injector so i had it replaced then there was ticking, i replaced the spark plug and it had oil on it but fixed the problem. the other day while driving i stepped on the gas on a roll and the car shifted from 2nd to 1st and the tick/knock came back as it does after i drive it hard but usually goes away. its been about a week and its still there. today i replaced all plugs and found spark plug from cylinder 8 has oil again. i started the car and tick/knock is still there, i disconnected coil #8 and the tick went away. it ticks from idle to about 2k rpms and stays with engine speed. it still has all the power as it should. problem could be?

[Q451990]

I'm guessing the oil on the spark plug is coming from a leaking valve cover? That's usually the issue.

Heath

[trayday]

if there is not oil on the exterior?

[Q451990]

Oh... no. It would be puddled on the threads and where the ceramic part meets the metal if it was a bad gasket. You're saying it's oil fouled?

If disconnecting that cylinder's coil makes the noise go away, that can't be good... almost sounds like piston slap that you're not hearing due to a lack of combustion on that cylinder.

Heath

[trayday]

oil is on the threads but not on the ceramic, the plug was only about 10k miles old also. im out of warranty, reason im trying to figure it out.

[Q451990]

Might want to run a compression test next...