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Thread: Spark, Advance, Min. Spark Question

  1. #21
    Tuner in Training
    Join Date
    Mar 2018
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    36
    Yes you are making sense. The Airflow table is a representation of what the throttle body airflow on a bench. The small table offers more scaling on the smaller throttle movements while the large table is for the larger ones. My method is to increase the airflow values in the Airflow table below 1V. As you mentioned the Small/Large Range tables are an inverse. I reduce the voltage in all rows on the Small Range Table and the lines <1V in the Large Range Table.

    What this does is it tells the ECM to keep the TB open longer and will prevent the ECM from closing the TB to early and then have to compensate by opening it back up. This is what causing the surging/jerking when slowing down and at idle.

  2. #22
    Tuner breal5825's Avatar
    Join Date
    Aug 2019
    Location
    Sylvania, OH
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    65
    Quote Originally Posted by richhurley View Post
    Yes you are making sense. The Airflow table is a representation of what the throttle body airflow on a bench. The small table offers more scaling on the smaller throttle movements while the large table is for the larger ones. My method is to increase the airflow values in the Airflow table below 1V. As you mentioned the Small/Large Range tables are an inverse. I reduce the voltage in all rows on the Small Range Table and the lines <1V in the Large Range Table.

    What this does is it tells the ECM to keep the TB open longer and will prevent the ECM from closing the TB to early and then have to compensate by opening it back up. This is what causing the surging/jerking when slowing down and at idle.
    OK so... bottom line, we're only making a 5% change to the way this thing functions so there's virtually no risk of engine damage or anything like that. Cool... Many thanks for the confirmation.

  3. #23
    Tuner breal5825's Avatar
    Join Date
    Aug 2019
    Location
    Sylvania, OH
    Posts
    65
    Quote Originally Posted by richhurley View Post
    Yes you are making sense. The Airflow table is a representation of what the throttle body airflow on a bench. The small table offers more scaling on the smaller throttle movements while the large table is for the larger ones. My method is to increase the airflow values in the Airflow table below 1V. As you mentioned the Small/Large Range tables are an inverse. I reduce the voltage in all rows on the Small Range Table and the lines <1V in the Large Range Table.

    What this does is it tells the ECM to keep the TB open longer and will prevent the ECM from closing the TB to early and then have to compensate by opening it back up. This is what causing the surging/jerking when slowing down and at idle.
    I loaded these tables today. It’s better but still not perfect. I think I’ll try reducing the idle RPMs now and see if that helps. Thanks for pointing me in the right direction on this issue.