Misfire problem

Lincoln Mark VIII

  1. sprocket

    sprocket Well-Known LVC Member

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    Hello! It's been awhile since I have posted here. My '96 still lives...maybe.

    The other day I pretty much put it to the floor to get around traffic and immediately a misfire developed. I didn't really notice it running that bad on the highway but the CEL was flashing. I was only a few miles from work. At low speed it was really bad and died when I pulled into my parking spot. I started it at my break and it seemed like it was misfiring badly. I had it towed home. It took a long time to link to my code reader. After like 10 minutes it showed a couple of O2 sensor codes and P0302 for a misfire on cylinder 2. I checked the plug. It looked great. It was even at the correct gap. No oil in the plug well. I changed it anyway. No change. I have spare plug wires so I changed the #2 plug wire. No change. I have a couple spare coil packs. I tried them both. No change. I'm not sure what is left other than the injector, but I smell fuel in the exhaust. I can't keep starting it or I'll destroy the cats.

    It seems like it is misfiring on more than one cylinder. It's so rough that when I disconnect individual injectors it's hard to tell the difference. For sure #2 makes no difference. I also don't understand the big delay connecting to the code reader.

    Another unusual thing is that when parked at idle the CEL is NOT flashing with an obvious misfire. But if I clear the codes, P0302 comes back.

    I'm wondering if the ECU may have gone bad. Any help or suggestions would be appreciated!
     
  2. Danny351C

    Danny351C New LVC Member

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    I think your car needs to rev up and clear its throat. I have a stock 94. It has alot of valving going on. Try running some cleaner like B12 Chemtool and seafoam thru it. I also run a little MMO into my fuel now and then. To each their may on the ratio. Be though as it may, I personally run 10 oz max of Marvel per tank of gas and its running great. No smoke either. Disconnect BOTH terminals off your battery for 5 minutes and reconnect. This will reset the cpu completely. Take it out on the highway and blast it out.
     
  3. sprocket

    sprocket Well-Known LVC Member

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    Thank you! I think you might be correct about the problem. I will do the Seafoam, piss off the neighbors and then blow her out good. Hopefully that solves the issue.
     
  4. sprocket

    sprocket Well-Known LVC Member

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    That didn't solve it. Still misfiring. Same code P0302
     
  5. Right on the Mark

    Right on the Mark Dedicated LVC Member

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    Misfire can also be valve/ valve spring related.
     
  6. sprocket

    sprocket Well-Known LVC Member

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    No compression on cylinder 2. I suspect a broken valve spring. Is there info here on how to change it? I will search...
     
  7. Right on the Mark

    Right on the Mark Dedicated LVC Member

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    You will need tool that screws into spark plug hole so you can be hook up to compressor. This holds the valves up tight. Then you need tool to remove spring on head.
     
  8. sprocket

    sprocket Well-Known LVC Member

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    The valve springs are not broken. I'm not pulling the head. Not at 230,000. She's junk. Time to part out? I have room in the front of my garage. Unless someone thinks I can still fix it with the head on. Dropped valve, broken valve, broken seat...
     
  9. Right on the Mark

    Right on the Mark Dedicated LVC Member

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    Do a leak down test. NOT a comp test. But most likely chip in valve.
     
  10. sprocket

    sprocket Well-Known LVC Member

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    I don't have a tester but I think I can rig something up with my compression tester and get compressed air into the cylinder.
     
  11. Right on the Mark

    Right on the Mark Dedicated LVC Member

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    Any friends with one?
     
  12. sprocket

    sprocket Well-Known LVC Member

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    Pretty sure not. I wonder what I might learn that would be of any value. What could be wrong that wouldn't require the removal of the head?
     
  13. Right on the Mark

    Right on the Mark Dedicated LVC Member

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    Just nice to know , if you had leak down tester. With this you can tell if its intake valve or exh valve or rings. But yes still a sucky outcome
     
  14. sprocket

    sprocket Well-Known LVC Member

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    Well are you in MN?
     
  15. Right on the Mark

    Right on the Mark Dedicated LVC Member

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    Nope sorry NH lol
     
  16. chris2523

    chris2523 93 Mark VIII

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    you may have also cracked a piston, either way, sounds like mechanical damage.
     
  17. Greyghost

    Greyghost New LVC Member

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    The throttle bodies crack/fissure At the thin areas. In my 98 it made it run wack, that and a bad diaphragm style fprc. Had changed all my hoses and emissions lines and kept hiccuping.....when I refined the solutions to reseal and fix the tb the car ran like new with new plugs and sealed coils with no cracks and such.

    8F1F584E-8D02-4E26-BB58-CD0504E5E7CA.jpeg
     
  18. sprocket

    sprocket Well-Known LVC Member

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    I'm not fixing it. It's a '96. Any input on what parts I should remove to sell would be appreciated
     
  19. chris2523

    chris2523 93 Mark VIII

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    pcm, vrcm, and imrcs are one year only parts.
     
  20. sprocket

    sprocket Well-Known LVC Member

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    Do I have to tear it apart to get the IMRCs or can I just remove the actuators? I actually have another set of '96 IMRCs
     
  21. chris2523

    chris2523 93 Mark VIII

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    the actuators are what generally go bad
     

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