Failed emissions!!

[crmzendrgone]

Been away far to long!
So I failed emission, high HC and CO, things done to engine prior to test: new plugs, wires, cap and rotor. Found when replacing all that, there was oil soaked plugs. More info, runs rough and sometimes misfires, misfires most when WOT.
So, the question anything easy to look for to get it to pass? I was looking on the old inner web and some suggest cat, I'll except that answer seeing as how last one installed was around 2009-10ish. It has 220k miles. Could be time for an overhaul. Any comments suggestions; good, bad, funny are all welcomed.

I'm ruling out EGR, new one just one year old. Umm, just had to put a new fuel pump in few months ago. Ah, maybe intake gasket, that could be leaking.
My concern is the oil soaked plug, valve seals?
Again, thanks

 

[OldCracker29]

I would guess a clogged cat or O2 sensor. As for oil on the plugs...could very well be worn valve seals.

 

[Draenor]

I would guess a clogged cat or O2 sensor. As for oil on the plugs...could very well be worn valve seals.

+2 on the valve stem seals. If oil is getting into the combustion chamber it is possible not all is burned and flowing down the exhaust. This can foul the O2 sensors and clog the cats.

Pull the O2 sensors, pre and post and look for oil. If both are covered, its leaking oil pretty bad and the cats may be oil soaked. You can possible fix the valve stem seals, clean the sensors and hopefully, burn off the oil. If not, the cats would need replacing.

The EGR could also be plugged with carbon due to the excess oil leakage.

 

[PenguinLTZ]

At 220K, valve stem seals may be just the beginning.

 

[txab]

At 220K, valve stem seals may be just the beginning.

+1

 

[Black02Silverado]

Just curious, but what is this specific engine? A few more details would be nice.

As long as it isn't in a Ridgeline you will be OK.