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205 Misfire Cyl 1 w/out Cyl Cutout aka Coax it a bit at startup and it will idle fine

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    205 Misfire Cyl 1 w/out Cyl Cutout aka Coax it a bit at startup and it will idle fine

    I have been having fun with the initial idling of my S54. When i start the engine i get this spluttering sound (which presumably is the misfire) at idle. However, if i give it a bit of gentle throttle for 10-20 seconds or so the idle even out and the car sounds fine.

    I am running native CSL software with a MAP and IAT but i have been for many years without issue.

    I read the codes and got "205 Misfire Cyl 1 without Cyl Cutout".

    Because the spark plugs are new NGK DCPR8EIX Iridium's and have been in the engine for a few hundred miles. I thought I would try replacing the coil pack on cylinder 1. This made no difference.

    Luckily i had a spare set of fuel injectors so i got them cleaned and fitted them. It feels like i have another 100HP. So they must have been a but filthy.
    It's amazing how a gradual lack of performance goes almost unnoticed. I thought my Vanos was giving up when getting an almost VTEC like response.

    Sadly, the idle issue remains.

    It does seem that outside temperature could be an issue. I was stranded at a friends house when i tried to leave at night. The temperature was 1 degree above freezing. The throttle coaxing would not work then. However, the next morning at 6 degrees celsius 41F. I got it to idle and then drove the 60 miles home.


    Has anyone had a similar issue with their engine?
    Last edited by ac427; 01-30-2024, 07:04 AM.

    #2
    OE NGK plugs for the s54 are DCPR8EKP or NGK-7415.
    You mentioned your DCPR8EIX only in for few hundred miles, which plugs were you running before?
    Do you hear pinging when driving between 2k-3k rpm?

    Comment


      #3
      Originally posted by Halftim3 View Post
      OE NGK plugs for the s54 are DCPR8EKP or NGK-7415.
      You mentioned your DCPR8EIX only in for few hundred miles, which plugs were you running before?
      Do you hear pinging when driving between 2k-3k rpm?
      DCPR8EKP are the the correct platinum spark plugs but DCPR8EIX Iridium plugs are listed as optional. I have run them previously at least once. As a rough guide the platinum's are good for approx 40k miles and the iridium's are good for approx 60k miles.

      The engine runs fines once the idling has been coaxed. I drove 60 miles after this last weekend.

      Perhaps it is a dodgy spark plug. I'll check and try to get a DIS Vanos test done too.

      Have you had a bad experience with the iridium spark plugs?

      Perhaps the spark plug in cylinder 1 is not tight enough when cold. I'll investigate.
      Last edited by ac427; 01-30-2024, 07:11 AM.

      Comment


        #4
        When diagnosing a misfire like this (or anything with multiple similar parts in play) its always best practice to swap a known good part to your problem area (in this case the cyl#1). The best way to accomplish this is by swapping from another cylinder instead of replacing with new. The reason is a new part could be bad and you've also introduced a new variable.

        So like you on your injectors, you don't know they are good, I agree they are likely and the chance they aren't is small but its still there.

        What I would do is swap your spark plug from cyl#1 to #2, if your misfire goes to cyl#2 you know the plug is the issue, but if it remains it hasn't cost you anything either. At the same time I would swap the coil with cyl#3. If it still misfires I'd swap the injectors with cyl Blogs If it misfires after that then I would look for a mechanical issue with cyl#1.
        '09 HP2S, '12 R12GSA, '00 Black 323iT, '02 Alpine 325iT (Track Wagon), '02 Alpine 330iT
        Instagram @HillPerformanceBimmers
        Email to George@HillPerformance.com

        Comment


          #5
          Originally posted by George Hill View Post
          When diagnosing a misfire like this (or anything with multiple similar parts in play) its always best practice to swap a known good part to your problem area (in this case the cyl#1). The best way to accomplish this is by swapping from another cylinder instead of replacing with new. The reason is a new part could be bad and you've also introduced a new variable.

          So like you on your injectors, you don't know they are good, I agree they are likely and the chance they aren't is small but its still there.

          What I would do is swap your spark plug from cyl#1 to #2, if your misfire goes to cyl#2 you know the plug is the issue, but if it remains it hasn't cost you anything either. At the same time I would swap the coil with cyl#3. If it still misfires I'd swap the injectors with cyl Blogs If it misfires after that then I would look for a mechanical issue with cyl#1.
          I agree but the injectors are good because i had them refurbed, tested and fitted them within a week of receiving them. Also, the car runs a whole load better than it did on the original set of injectors.

          I was going to do as you said with with coil pack and spark plug swapping but i had some fun with the rubber insert in the spark plug socket. Anyway the upshot is i will swap the coil pack to cylinder 3 and spark plug to cylinder 2 and see if the fault travels.

          Comment


            #6
            Originally posted by ac427 View Post
            I agree but the injectors are good because
            They aren't "good" just because they "tested" ok on a flow bench. I'm not saying they are bad, but new parts out of the box are bad not all the time, but it does happen. If you swap injectors from a known good cylinder you 100% know you are putting in a good injector.

            And I'm not saying you were wrong to replace them, I just think you might have done it prematurely as you've needlessly added a variable IMO.
            '09 HP2S, '12 R12GSA, '00 Black 323iT, '02 Alpine 325iT (Track Wagon), '02 Alpine 330iT
            Instagram @HillPerformanceBimmers
            Email to George@HillPerformance.com

            Comment

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