1998 Escort 2.0 SOHC – automatic trans - P0304 code | Ford Escort Owners Association (FEOA)

1998 Escort 2.0 SOHC – automatic trans - P0304 code

Discussion in 'General Discussion' started by Gene Brink, Jan 2, 2019.

  1. Gene Brink

    Gene Brink FEOA Member

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    Hoping experts on Escorts can help me out (posted here rather than in the performance category).
    Having a problem that is showing up as code P0304 – a misfire on cylinder #4. Here are some general bits of info and thoughts. I’d appreciate any further ideas or thoughts anyone might have.

    1998 Escort 2.0 SOHC – automatic trans

    Head redone approx. 10k miles ago – compression good on all cylinders. Engine runs great most of the time.

    Misfires generally caused by:

    Faulty spark plug (all plugs look great – new when head was done), faulty plug wires (new when head was done) – switching #4 plug and wire to #2 cylinder made no change when fault code comes up so believe plug and wire is NOT the problem (also eliminated the coil pack since all plugs are firing as evidenced by plug condition when removed)

    Faulty crankshaft or camshaft position sensor – As the problem is intermittent BUT always the same cylinder this does not seem likely as I would expect a faulty sensor to cause a misfire on any of the four cylinders not the same each time (this because the sensors only send an electronic signal based on magnetic pulses caused by teeth on the crank and/or cam).

    Faulty fuel injector – as a misfire code will trigger if any single cylinder develops slightly different power than other cylinders this seems as though it could be the cause providing the injector is marginal (which would account for the engine running properly most of the time?)

    Faulty ECM – since it references crankshaft/camshaft sensor input to perform engine management and send signals for timing, injector firing, etc it seems as though this could be the problem if the flaw is a repeatable glitch.

    Faulty wiring or connector – assuming the connection/wiring is marginal this certainly could be an intermittent problem and would expect that the wiring to the fuel injector for #4 would be the culprit, right?

    Anyone have any experience with a similar problem and if so what did you do to correct? Thanks in advance for any ideas.
  2. Gamer92

    Gamer92 FEOA Donator

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    Did valve seats get replaced on head?
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  3. Gene Brink

    Gene Brink FEOA Member

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    Yes, they were replaced.
  4. rokon

    rokon FEOA Member

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    since the compression is good, try swapping plug and wire with another cylinder and see if you get a different code, if the misfire moves to the swapped cylinder.
  5. zzyzzx

    zzyzzx FEOA Member

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  6. zzyzzx

    zzyzzx FEOA Member

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    What brand spark plug wires?
    What brand and model number for the spark plugs?
    Are you absolutely sure that the plugs and plug wires are property seated?
  7. Gene Brink

    Gene Brink FEOA Member

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    As indicated tried this but the fault continues to be cylinder #4 only.
  8. Gene Brink

    Gene Brink FEOA Member

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    Motorcraft wires, Autolite plugs (XP5144). Plugs torqued to spec, wires seated just fine - both ends.

    Generally the engine runs fine most of the time (sometimes for a couple of months) before the code throws again.
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  9. rbailin

    rbailin FEOA Member

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    When you switched the #2 and #4 plugs and wires, did you keep them plugged into the same locations on the coil? Perhaps one of the coil sockets is corroded? I don't suggest buying a new coil, but a cheap used one from the jy might be a good test.

    Try running a bottle of Chevron Techron in your tank to see if it cleans a dirty injector. Try swapping the #4 injector with another one. Make sure the FI connector is on securely (the retaining tab frequently breaks off).

    It's possible the #4 valve seat is coming loose. If it does, it will make a lot of noise but won't shatter and damage the engine. If none of your fixes work, just live with it until it gets worse and the engine loses power consistently. At that point a compression test will show the problem.
  10. Gene Brink

    Gene Brink FEOA Member

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    Thanks. Coil pack sockets are pristine - both wires and plugs were switched. Engine isn't making any unusual noises so do not think a valve seat is coming loose (would expect a more consistent problem code I think) so am leaning for electrical - either a connection or a marginal injector. I'll try swapping out with another to see what happens. Thanks for your suggestions.
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  11. novanutcase

    novanutcase FEOA Member

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    Check the wiring on the loom prior to the connector that connects to the coil pack. One of the wires on my loom had rubbed the casing off and it was arcing over to the other wire.

    John
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  12. marclar

    marclar Moderator Staff Member

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    i apologize im at work and didn't read the whole post.. but i will tell you how i would diag it.
    first iridium plugs are the wrong plug for the engine, they will work, but the engine calls for platinum plugs..

    swap plug 4 to cyl 2, and 2 to 4.

    if miss remains

    swap plug wire 4 with cyl 3, and 3 to 4

    if miss remains

    perform compression test, if compression is good:

    swap injector 4 with injector 1,

    if miss remains perform cylinder leak test on #4
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  13. Gene Brink

    Gene Brink FEOA Member

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    Update for anyone. Turned out to be a faulty spark plug wire. :( Everything checked turned out to be okay (EGR, injectors, etc...) so I checked each wire for continuity - all good but if I twisted and pulled on the wire the continuity would break up even though the all was okay most of the time (hence the intermittent problem). A new set of wires and the problem has gone for a couple of weeks now. So simple a fix but hard to pin down. Thanks to all with suggestions.
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  14. novanutcase

    novanutcase FEOA Member

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    Sometimes the diagnosis is the hardest part of tbe fix.

    John

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