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CrownVic Backfire & Stutter

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  • CrownVic Backfire & Stutter

    Does anyone have any idea what would cause a CNG vehicle to backfire and stutter on acceleration? This usually happens when the vehicle is below a half a tank of fuel, but this is not always the rule. However, when I am near empty, I can bet on some hesitation and stuttering while accelerating.

    This is specially daunting when on the freeway and trying to either merge into traffic or trying to pass.

    Thanks in advance for any help!

    Frank Q.

  • #2
    Re: CrownVic Backfire & Stutter

    Most common problem on the Crown for stuttering was plugs and coils. If the plugs are much over 30,000 miles, or if the coils are over 60,000 miles, they are highly suspect.

    Second on the list would be a toss up between the coalesing filter and the Compuvalve being dirty or oily. Note: Anyone working on the pressure side of the system, ie the primary regulator, the filter(s), or any of the fuel lines, should have their head out of the sand and be VERY familiar with CNG fuel systems.

    Cleaning the Compuvalve is possible but not recommended for the non-trained individual. I would go with the plugs and coils first.



    • #3
      Re: CrownVic Backfire & Stutter

      I would second the plugs and coils. We've had to replace a few of them on rough running vics. If your Crown Vic is factory dedicated CNG then you don't have to worry about the compuvalve since it doesn't have one.


      • #4
        Re: CrownVic Backfire & Stutter

        Now comes the expensive question! Who in North Orange County/Long Beach area can check and service this vehicle? Or is the coil replacement a DIY job?

        As an FYI, I am not afraid of dirt & grease, just things that go BOOM!


        • #5
          Re: CrownVic Backfire & Stutter

          "Who in North Orange County/Long Beach area can check and service this vehicle?"

          I know of two Ford dealers that are CNG shops in the areas listed:

          (1) Villa Ford in Orange

          (2) Pacific Ford in Long Beach.

          I've had my 1997 CNG Crown Vic serviced at Pacific since I will no longer patronize Villa Ford. Prior to our marriage, my wife had a bad sales experience at Villa Ford; an experience that left us unable to trust that dealership or its employees.
          Last edited by Tax Counsel; 12-18-2008, 07:08 PM. Reason: My typing still has not improved.


          • #6
            Re: CrownVic Backfire & Stutter

            Thanks for the info about Pacific Ford. I, too, have had a couple of run ins at Villa and prefer not to go back to them if at all possible.