That #@&*! Midfire!

Lincoln LS

  1. 2004 LSE

    2004 LSE New LVC Member

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    Long time reader, first time poster... .

    I have a 2004 LSE V8 with 106k miles. I bought it 7 months ago as a 2nd car (at 103k miles), and it ran fine. It needed some cosmetic love, so I've enjoyed getting her back into shape (repaired and repainted the bumpers myself, detailed the interior, replaced broken trim, etc.). It soon developed a misfire on cylinder 6, so I combed this forum to learn everything I could about this car. After I serviced the car (oil change, filter changes, replaced trans fluid, filter, and gasket), I then replaced the heater control valve, valve cover gaskets, COPs, spark plugs, and checked all wiring (and cleaned out the spark plug wells). I also checked the fuel injectors. I used a NOID light to verify signals. I wasn't getting a signal on COP 6, so I took it to a mechanic. He verified that no signal was coming from PCM, so the driver likely was bad. The wires back to the PCM have continuity and no attenuation/resistance issues. This forum recommended S.I.A. Electronics, so I sent in the PCM. That's when the real trouble began.

    S.I.A. rebuilt the driver for COP 6 and #6 no longer misfired, but now cylinder #8 misfired. I rechecked my work, swapped around COPS, spark plugs, fuel injectors, but #8 still misfired. No signal from the PCM. I sent it back to S.I.A. THREE more times (twice on my dime) and they could not find any problems. This last time, they replaced the capacitors for #8 driver, wrote me a nasty note, I reinstalled the PCM on Monday and the LSE ran awesome for 80 miles yesterday. On the way to work this morning, it began misfiring again (flashing CEL). I left my OBDII reader at home, so I do not know the code yet.

    Can someone please lend me some guidance? Have I overlooked anything? I know I'll never recommend S.I.A. to anyone. This Lincoln is too nice to abandon. I'm a decent shade tree mechanic, but I'm about ready to call UNCLE. Please HELP!
     
  2. AmsterDutch

    AmsterDutch Dedicated LVC Member

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    When did you replace the fuel filter last?
     
  3. 2004 LSE

    2004 LSE New LVC Member

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    I replaced the fuel filter at 103k miles when I did the major service. I retrieved the OBDII codes today during lunch: P0316 and P0304. I just swapped out the COPs on #4 and #1 and the codes went away, although when I rev the engine, the revs take an abnormal amount of seconds to return to idle. Going to take another test drive now.
     
  4. AmsterDutch

    AmsterDutch Dedicated LVC Member

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    Have you cleaned out the intake as of late? Sounds like you need a good hot soak with some sea foam spray it won’t hurt anything
     
  5. 2004 LSE

    2004 LSE New LVC Member

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    I'll give it a try.
     
  6. AmsterDutch

    AmsterDutch Dedicated LVC Member

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    Take the car for a good hard drive park in driveway Spray the sea foam nozzle in the vacuum hose line on top of the intake manifold while another person keeps the rpms at 1500-2000 while you empty the whole can of spray into the vacuum hole ...NOTE* The car will chug chug chug while vacuum line is out but won’t die with the proper rpm’s T 1500-2000 replaced the vacuum air line/hose and turn car off so she can soak in the hot tube for awhile lol 13-15 minutes later take her for a good hard drive again and clean the carbon out ....warning go out in country if possible for Drive she will smoke goood
     
  7. joegr

    joegr Dedicated LVC Member

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    What brand are the COPs?
     
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    • 2004 LSE

      2004 LSE New LVC Member

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      Denso. They only have 2000-2500 miles on them. I replaced COP #4 and it ran well on the test drive. The next morning, it misfired again, but on #3. I replaced COP #3. Running OK so far. I don't know if I got bad COPs or if the 4x-rebuilt PCM is causing them to go bad.
       
    • 2004 LSE

      2004 LSE New LVC Member

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      BTW, I have black leather seats from a 101k mile 2006 LS I need to sell. Good condition. Is there a place on this forum to list them?
       
    • joegr

      joegr Dedicated LVC Member

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      Works the other way, your cheap coils are probably damaging the PCM over and over again.
       
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      • 2004 LSE

        2004 LSE New LVC Member

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        Gonna replace them with Motorcraft DG529s.
         
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        • 2004 LSE

          2004 LSE New LVC Member

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          UPDATE: I replaced with the Motorcraft COPs and it seems to idle and run better. They also fit more snugly on the plugs. I noticed the conductor inside the boot was longer. Fingers crossed that they last longer than 2000 miles.

          Just to clarify about the PCM: the driver circuit for cylinder #8 came back dead from S.I.A. THREE times before they fixed it correctly. It was not outputing a signal. I find that unacceptable. Off-brand COPs were not killing the PCM since I've owned the car. I suspect the previous owner drove it a long while with a bad COP on cylinder #6 which damaged the PCM driver for that cylinder. That is why I sent it to S.I.A. in the first place. It came back the first time with driver #6 fixed, but with a dead driver circuit for #8.
           
        • joegr

          joegr Dedicated LVC Member

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          Did you replace the plugs when you replaced the COPs just now?

          SIA runs a test on the PCM that emulates the engine. It's hard to believe that they wouldn't catch a failed driver (but maybe they didn't). Is it possible that your #8 coil killed it as soon as it was installed? That probably is unlikely too.

          Anyway, bad COPs can damage plugs, and bad plugs can damage coils. Ford insists that anytime a COP is changed, the spark plug must be changed too, even if it's only a week old. Odds are that you are okay if you didn't, but it is a risk. It's also very important that the plug gaps all be set to 1.0mm. (Yes, the box says pre-gap'd, but rarely are they all correct.)
           
        • RigsLS

          RigsLS Dedicated LVC Member

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          Imagine this!
           
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          • lincoln_zero

            lincoln_zero Dedicated LVC Member

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            Im not an engineer or electrician, so hence my curiosity as to why this can even be? Spark plugs seem pretty rudimentary. Terminal (nut), copper core, electrode that makes spark. Ignition coils are just windings that deliver current. I'm surprised this can even be an issue. I guess its just very sensitive equipment.
             
          • joegr

            joegr Dedicated LVC Member

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            I think that it can cause the spark plug to carbon foul due to the poor combustion due to the weak spark. Anyway, the plug is cheap compared to the coil.
             
          • RigsLS

            RigsLS Dedicated LVC Member

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            Wiring harnesses and connectors get so little attention when dealing with misfiring on these cars.
             
          • AmsterDutch

            AmsterDutch Dedicated LVC Member

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            I agree
             

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