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Discussion Starter #1
I got a CEL P0304: Cylinder 4 misfire detected. I went and got some new spark plugs to put on. Upon pulling out #2, there was a small amount of oil that had build up/dripped out off of the end of the spark plug wire. I wiped it off and pulled out the spark plug. There was no oil visible or within the spark plug (where it ignites) and it looked okay (normal). Do you guys know why there was oil there? There were no oil in any other ones. Thanks in advance.
 

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Tube seal around the spark plug tube is leaking oil. Definitely the source of your misfire. Replace the valvecover gasket and tube seals (since this all comes off to do the job, change it all) and put new plug wires on as well. Don't put new plugs in until you change this stuff as you'll just end up fouling the new plug.
 

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Discussion Starter #4
tube seal

Is it hard to replace the tube seal? Sorry, I'm new to the Subaru scene (just bought my subie a couple of days ago) so I'm still learning as I go.
 

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FalconRS said:
Tube seal around the spark plug tube is leaking oil. Definitely the source of your misfire. Replace the valvecover gasket and tube seals (since this all comes off to do the job, change it all) and put new plug wires on as well. Don't put new plugs in until you change this stuff as you'll just end up fouling the new plug.
I wouldn't say definiately. Misfires can be caused by a lot of problems. Igntion coil, plug wires, plugs, compression loss, faulty fuel injector, ECM, etc. I would start by fixing the valve cover leaks first then install a new set of plugs and wires. You don't want to get that old oil on new parts. Then see if you still have the misfire. If you do, look elsewhere. Possibly coil pack.
 

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cvang84 said:
Is it hard to replace the tube seal? Sorry, I'm new to the Subaru scene (just bought my subie a couple of days ago) so I'm still learning as I go.
Not really. You just pull the valve cover off and replace the two spark plug seals, valve cover gasket, and 5 sealing washers around the bolts. It's a tight area to work in, but it's not that bad. If you do one side, do both sides. And replace all the gaskets listed above. Look in the DIY section cuz there is a...well...DIY for the valve cover gaskets.
 

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Without a buddy it can be done in one hour. :)

Oh, quick note, remove and replace the plugs while the rocker covers are off.. makes it a little bit easier.
 
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