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Thread: Spark cylinder offset

  1. #1

    Spark cylinder offset

    Maybe someone more educated with this Coyote platform can chime in and explain this to me.

    Engine -> Spark -> Advance -> Cylinder Offset

    Why are the values different between and NA coyote/ Roush/ Cobrajet? What are the purpose of these tables? Why are some cylinders set differently than others?


    Here is CYL #4 Multp under Cylinder offset for each of the follwing.

    Cobrajet



    Roush


    NA Coyote
    Last edited by Blueprint; 07-29-2016 at 11:12 AM.

  2. #2
    This allows you to adjust the spark timing per cylinder in case one knocks more than others.
    The values in this table are multiplied against the overall multiplier table and added to your final spark.

    As the multiplier table is negatives, this has a net effect of subtracting timing per cylinder.

  3. #3
    I see.

    So I assume it is safe to zero out these tables ( as the Cobrajet has them)?. That way I have one less thing messing with my timing.

  4. #4
    Quote Originally Posted by Blueprint View Post
    I see.

    So I assume it is safe to zero out these tables ( as the Cobrajet has them)?. That way I have one less thing messing with my timing.
    Depends. If you actually have a cylinder that knocks more than others, you'd just be making it knock more. The CobraJet has a different manifold which in a long way could change the tendency for some cylinders to knock over others (might have better distribution, etc), though there's also individual fuel corrections that should take care of that. Tough to say why they did what they did.

  5. #5
    Quote Originally Posted by Bugasu View Post
    Depends. If you actually have a cylinder that knocks more than others, you'd just be making it knock more. The CobraJet has a different manifold which in a long way could change the tendency for some cylinders to knock over others (might have better distribution, etc), though there's also individual fuel corrections that should take care of that. Tough to say why they did what they did.

    I believe that file was a super cobra jet, so no manifold, supercharged.


    Another thing to consider, is the starting file. My car is a 5.0, however my car has always been tuned using a Roush file, which in this area differs from the NA Coyote.


    Think I might just disable it. My car is on e85 with a mild tune. Ive never seen any knock, and I have the knock sensors setup to pull timing.

  6. #6
    Senior Tuner
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    Copied from their patent:
    Cylinder to cylinder differences such as combustion rates, swirl rate, spark plug conditions, etc., cause each cylinder to have optimal performance (MBT) at different spark timing. For example, knock may occur at different spark timing for different cylinders. An engine control strategy that retards all cylinder's timing, if any one knocks, loses potential benefits by retarding the non-knocking cylinder's timing. An adaptive knock control system retards only the timing of the cylinders that knock, allowing maximum advance up to MBT, for each cylinder.

    Each cylinder has its own knock history and adaptive timing based on its history.

    From the looks of it 2015 coyotes, which are not just rpm but load based as well, have the front cylinders not removing as much timing. The back cylinders are left alone. Makes since since they would be getting slightly more air and fuel as they are closer to the intake opening. I could see on a roots style FI disabling it with all 0's, but on any manifold with out a main centralized air intake port I wouldn't leave it disabled. tune as normal for knock with it zeroed til you get as close to maximum as you think you can maybe .5 degrees of knock. add .25 or .5 to the first four cylinders in the RPM range you hav knock see if the knock goes away. slowly lower it starting at cylinder one and working to cylinder 4 and see when you can max out your spark.


    Maybe Eric can set up the scanner to register exactly what cylinder caused the knock...
    Last edited by murfie; 07-30-2016 at 01:21 AM.