fouling plugs/check engine

[cpwamw]

I had my 98 4L explorer X vin in for a tune up in october as it started running rough and the check engine light came on. They tuned it up and replaced the plugs and plug wires. Ran O.K. but fuel economy was never the same. Yesterday it started running real rough and check engine light came on again. Took it to a different dealer and they said plug #6 was fouled. They replaced and it ran O.K. till tonight when it started running rough again and the check engine light came on again. I'm going to take it back in the morning. Any suggestions? Continuing to foul plugs seems like their missing something.

 

[justin's_94]

What is fouling the plugs, oil, gas, etc. It could be you are getting some oil or gas on the #6 piston, it happened to me onetime on an old 302 I had. I wish I had a solution for you, but mine was to rebuild the engine. It had 200,000 mles on it. Take it to a mechnic that is trustworthy and a compression test done and ask him what could be fouling the plugs.

 

[mrboyle]

Have you had the fuel pressure tested? It sounds like your fuel pressure regulator is bad, forcing the engine to foul out the plugs.