Question about 1998 Mercury Grand Marquis

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Cylinder 4 is still misfiring on my 1998 Grand Marquis. I just had new spark plugs put in. What could be the problem?

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Well it could be a few things if you pull the plug out and there is oil sludge on it the engine is dirty. You can try and run some rislone in it for about 100 mile then change the oil short of an overhaul. Now if you pulled the plug out and it has water on it you may have a water jacket leaking. It could be a burnt valve most of the time if it is a burnt valve when you put the engine under a strain it will run worse.

Posted on Nov 05, 2010


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