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2004- OBD Code P0304 where is cylinder #4?

Discussion in '2002 - 2005 Ford Thunderbird' started by 04tbirdjerry, Feb 12, 2019 at 7:02 PM.

  1. According to chart I have, the #4 cylinder is on pass side, nearest to firewall. I checked the harness, replaced both the plug and coil pack, and I still have rough idle and keep pulling code 0304 (misfire cylinder 4) and 0316 (misfire detected first 1000 revolutions). WTF? Is my chart wrong? Is #4 back pass ? Thanks for any suggestions and/or help.
  2. biddle

    biddle Forum Moderator Staff Member

    Please include the model year(s) of the car in the subject of the post on future posts. I've added this for you.
    ChuckH262 likes this.
  3. You have the right location for #4. Can you clear the code, and see if same code comes
    up again.
    biddle likes this.
  4. Thank you, yes, cleared the codes and they came back again. Car idles rough, but has power once moving. Not sure what else it could be. I also put some Seafoam injecter cleaner in last refill, in case that particular injecter was dirty. Plan to repeat that as it is recommended if you've never used before.
  5. biddle

    biddle Forum Moderator Staff Member

    You can also put 2002-2005.
    We have members with 1955-2005 models. Once a week a popular posts email is sent, it makes it easier to determine on the summary what year the post is about. Also, when the post is indexed in Google, it helps with SEO because the model year is in the URL.
  6. biddle

    biddle Forum Moderator Staff Member

    Here is a good thread to read about COPS and Spark plugs- https://forums.fordthunderbirdforum...-05-ford-thunderbird-ignition-coils-cop.5040/
    04tbirdjerry likes this.
  7. This isn't fun to bring this up, but how do you know that the new coil you used to replaced the existing one is truly a good coil? New does not always mean good & usable. I would take that new coil out & swap it to another cylinder. Easy to do since you have the cover off. See if this moves the problem. Truth be told if I went through the effort to remove the cover I would replace all of the coils on that side.
    Pelagic likes this.
  8. I did perform the old school screwdriver test. Coil off plug, but hot. Started motor and inserted driver into coil boot, was able to still get a spark jumping from boot to driver up to 1/2" away. This is best way to know you're getting juice to the plug. I'm perplexed now.
  9. Last edited by a moderator: Feb 13, 2019 at 6:18 PM
    Pelagic and biddle like this.
  10. Pelagic

    Pelagic Well-Known Member Lifetime Donor


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