I Did A Tune Up On My 4.6l 98 Xlt Expo And Found One Of The Spark Plugs Slightly Covered In Motor Oil (the Plug Located On The Farthest Passenger Side). It Reads Check Engine And Truck Shakes A Little. What Should I Do? I Talked To A Few Guys They Say That I Have To Open Up The Valve Covers And Replace Something... I Really Dont Know Much But I'm Doing My Best To Learn. Any Price Estimates For Fixing The Problem? Thanks.

 

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There are 2 possible places for the oil to be coming from. Either the valve guide seals in the head or up from the piston seal. It is probably from the valve guide seals and dripping down onto the spark plug.

I have no idea what the cost. There is probably a cheap way to band-aid it, like an oil additive, but if you plan on keeping the truck, I would get it fixed.

Glock

 

Well, if the engine is shaking, this could possibly be more severe than a valve guide. I would almost be more convinced that it is the piston seal(rings) in that particular cylinder. How many miles are on the truck? Sometimes a rough idle can be caused by comprimised compression in one or more cylinders. I went through this on an F-150 with a 5.0 efi once. It turned out to be a small hole in the crown of the piston, actually. But it would foul the plug in 30 min every time, to the point where it totally missed.---Ryan

 

how many miles were on that fouled plug? To have a fouled plug is not the end of the world...it happens. If you replaced it, and have put some miles on it, and that cylinder is not missing, it might not be that big of a deal. Like armorer is saying above, if it fouls often, then its a problem. If it fouls every 40k miles, i wouldnt care, I would just replace it when it fouled.
The shaking you are mentioning may have nothing to do with the fact that you found a fouled plug...how is it running since you replaced it?