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Spark Plug Question - '97 Crown Vic CNG

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  • Spark Plug Question - '97 Crown Vic CNG

    Hi there - new to the CNG Chat community - had a spark plug question for my '97 Crown Vic daily driver - searched the forums and found differing opinions on type. My situation - 125k freeway miles, plugs never pulled - runs like a charm with basic maintenance (oil,coolant,brakes). Your advice? Should I replace plugs/wires etc and if I replace the plugs, which ones (platinum, copper, iridium)? Also, I noted that the spark plug wires are quite tightly do you remove safely?
    Thank you in advance!!!

  • #2
    Re: Spark Plug Question - '97 Crown Vic CNG

    Just a shadetree mechanic's opinion:
    1. if they are 10 year old wires, you're asking for trouble trying to reuse them.
    2. I personally have used fancier plugs myself with no issues (platinum), but have been told recently by CNG mechanics that you're much better off using whatever standard plug the OEM suggests (source: Alt Fuel Systems in Mesa; I didn't attempt the maintenance on a 2000 F150 Bifuel)

    Good Luck!
    2008 GX (extended range, trunkless version)
    Polished Metal Metallic 2012 Civic Natural Gas
    Fuelmaker FMQ-2-36 (since 2001)
    Previously owned: 2000 GX (11 years), 1995 Bi-fuel Sonoma, 2000 Bifuel Tahoe, 2000 Bi-fuel F150


    • #3
      Re: Spark Plug Question - '97 Crown Vic CNG

      I have a 99 Crown Vic. When I tuned it up, we used the OEM Premium Platinum plugs, and the MSD Coil Paks (Better spark, and less than half the price of OEM) , and it runs like a "Bat outta .....".


      • #4
        Re: Spark Plug Question - '97 Crown Vic CNG

        If I might add:

        The 4.6, 5.3 and 6.8 Ford Modular engines have a strong history of plug seizures in the head. When you get the coil pack off the plug, put about a tablespoon of WD-40, Marvel Mystery Oil, or a good thin penetrating oil in the plug hole.

        With a HAND wrench (no air tools here, please!), loosen the plug about 1/3 turn and work the plug in and out. Even though the plug may feel like it will loosen ok, do this in steps. After the plug turns about 2 turns easily, remove the plug. After all the plugs are out, spin the engine over and blow the oil out. Coat the new plug threads with anti-seize compound and torque to specs. Overtightening the plugs causes more problems than one might think.

        Our department has had four 5.4 engines with plug blowout in the heads. These have been with original plugs, often under 10,000 miles. There are numerous on the car fix it kits but the secret is to keep the metal shavings out of the cylinder.