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Thread: Spark Idle for gen 2 with 18+Manifold & IMRC Removed.

  1. #1
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    Spark Idle for gen 2 with 18+Manifold & IMRC Removed.

    Where should I be for Spark timing degrees at Idle with a 2018 manifold with IMRC's removed?

    Thanks,

  2. #2
    Senior Tuner veeefour's Avatar
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    In bordeline and MBT, also in minimum spark...but also in your torque tables.

    The answer is more complicated then you may think - idle is TQ controlled.

  3. #3
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    Thank you for the reply Veeefour. I'm trying to see where in degrees should I be at Idle. I have it set to idle at 750rpm. Evans states I should be in the mid 20's but I have also read around 8-12 degrees. Before the manifold swap I was around 8 and had the rpm's within +- 10rpm with only adjusting the torque tables in MP 1. Now that I'm in MP15, my goal here is to have a smooth Idle without spark timing jumping around so much. Would you know if I have to adjust my Idle Airflow to help achieve this? Thanks. Edit: Forgot to mention I have a Procharger.
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  4. #4
    Senior Tuner veeefour's Avatar
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    Well MP15 is not suited for idle like MP1 was, even if this theoretically should be working this way. MP15 needs some SD adjustment.

    Imagine your 100% torque as 100% MBT spark. For example if MBT is 40 and BRDL is 20 you should be making 50% of torque.
    That is given other conditions are met like AFR. For most cases idle will end up being to high and idle logic will command a spark cut
    and you will end up idling at -2 to 0' which is not ideal. Those engine like to idle around 15'. Adjust spark MBT and BRL correlation
    to achieve a proper spark at idle. Adjust SD to achieve proper idle airflow.

    Only then go and touch anything in idle logic, most of the time its best left alone.

  5. #5
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    I have a ways to go to understand these torque based systems. Learning this doesn't come as easy to me but I enjoy learning. Thank you for the input. I will work on getting familiar with how to make the speed density adjustments. I know I need at least a 2bar map sensor to hook up to make the proper adjustments as the system map is inferred. Thanks again.