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CNG Spark Plug replacement advice needed for 2000 Ford CV P-71

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  • CNG Spark Plug replacement advice needed for 2000 Ford CV P-71

    Hi - was going to try changing spark plugs on my CNG P-71 2000 Ford CV and would like your assistance to make it as economical and logical as possible. Miles - 50K - original plugs and wires never removed. Car runs well - some occasional roughness in idle within first mile when cold - but then fine - averages 16mpg City - 20mpg Freeway

    Questions:
    Recommended plugs? Mfgr and part number
    Recommended plug torque? Don't want to over torque
    Should I change the plug wires? Mfgr and part number
    Installation Pearls of Wisdom to reduce frustration? Greatly appreciated

    Thanks in advance -

  • #2
    Re: CNG Spark Plug replacement advice needed for 2000 Ford CV P-71

    Hi There,

    Here's what worked for me:

    Recommended plugs? Mfgr and part number
    -Autolite XP103

    Recommended plug torque? Don't want to over torque
    -15 ft/lbs.
    -Make sure your car is stone cold. Let it sit overnight.
    -Do not use anti-seize
    -Yes, you really, really do not want to over-torque the plugs on these motors. the heads only have 5 or so threads for the plug to thread into.. and it's soft aluminum. They are notorious for ejecting spark plugs.. check out www.blownoutsparkplug.com to see what I mean.

    Should I change the plug wires? Mfgr and part number
    -There are no traditional plug wires in this car. Instead they use a coil on plug system or COPs where each plug has its own little coil.
    - You can use the same COPs from a regular Crown Vic - Motocraft DG508 or equivalent. Many people have had luck with aftermarket coils on ebay that cost $80 for a set of 8, instead of ~$80 each or $640 for a set of 8 for the Motocraft part.

    Installation Pearls of Wisdom to reduce frustration? Greatly appreciated

    -Turn the quarter turn CNG shutoff valve on your driver's side frame rail.
    -Disconnect the battery, ensure there is no ignition source and vent the gas out of the fuel rail by using the schrader valve (looks like a valve stem from a auto or bike tire)
    -Remove engine cover
    -Disconnect injector and coil connectors
    -Remove the the fuel rail - make sure you don't loose any injector o-rings!
    -Remove the bolts holding on the COPs and remove them as well.
    -Blow out the spark plug wells with compressed air to remove any debris
    -Carefully remove plugs on a stone cold engine.
    -Install plugs and torque to 15 ft/lbs.
    -use plenty of dielectric grease on the boots and springs of the COPs as well as the plug leads. I cleaned the injector and COP connectors with contact cleaner and applied grease to those connections as well.
    -I also cleaned the injectors while they were out and put some dielectric grease on the o-rings to ease install and hopefully make them easier to remove next time around.
    -Install COPs - make sure to not over-torque the bolt or it can split the fitting on the COP
    -Connect the injector and COP connections
    -Install Injectors/fuel rail/engine cove/battery, etc.
    -Turn back on the quarter turn and take it for a test run!

    It's been about a year and a half since I did it, so I'm sorry if I forgot some things, but hope that helps and good luck!
    Last edited by CNGBiker; 02-27-2010, 11:06 AM.

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    • #3
      Re: CNG Spark Plug replacement advice needed for 2000 Ford CV P-71

      I've been using the E3-E53 plug in my 02 CNG Crown Vic taxi and the results are impressive..., wait and see future posts if they handle the heat. I also found a Brisk CNG plug on ebay in England, they have a silver tip and are enginered to run CNG and may be the best plug on the market. They dont list a CV on their guide but the Moto SP405 croses to an NGK plug which spec matches and crosses in the gude to a Brisk plug GOR15LGS. $8 each. I can feel the power increase with the E3. I cooked the plats and Irid plugs including the autolites but my motor was very lean and new o2 cooled it off. Anybody know if you can flash comp chip to advance time 1 or 2 deg?

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      • #4
        Re: CNG Spark Plug replacement advice needed for 2000 Ford CV P-71

        Correction, I have an 00 CV...

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        • #5
          Re: CNG Spark Plug replacement advice needed for 2000 Ford CV P-71

          I have been using the MSD aftermarket (Red) COP units with the Autolite XP103 and they have ben flawless for me.
          I put them on about 65,000 miles ago, and they have ben running like a dream.
          I just pulled and replaced the plugs about a month ago (*because I am a bit anal...),
          the plugs showed almost no signs of wear and could have been put back into service without issue,
          but I changed them anyway(*).

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