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Thread: Trying to understand Pilot vs Main timing?

  1. #1
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    Pilot vs Main injection timing.. First tune attached

    Trying to tune my 06 cummins auto for the first time, has CAI and exhaust. I understand making small changes at a time.. I have added small amount of fuel up top. using timing calculator have figured out the main event.. but I am lost on how to setup the pilot event.. I zeroed out the post event. Thank

    I am having an issue with timing dropping at WOT.. Have attached a tune and log



    tune 1.hpl tune attepmt 1.hpt
    Last edited by NRunkle; 08-07-2019 at 03:25 PM.

  2. #2
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    Quote Originally Posted by NRunkle View Post
    Trying to tune my 06 cummins auto for the first time, has CAI and exhaust. I understand making small changes at a time.. I have added small amount of fuel up top. using timing calculator have figured out the main event.. but I am lost on how to setup the pilot event.. I zeroed out the post event. Thank

    I am having an issue with timing dropping at WOT.. Have attached a tune and log



    tune 1.hpl tune attepmt 1.hpt
    I'm not a cummins guy but it appears to be doing exactly as it's commanded to do IMO. Look at your ECM 7411 table. It's following that table perfectly. Your truck goes up to 19* when part throttle because it's using the transient table as it should in transient conditions. When you go WOT it seems to switch to the high air density table and i'd think it should with your current boost. Anyways If i had to guess i'd think it'd blend between all three of those tables, high, med, and low as boost ramps through them. Therefore i'd set them all the same until you understand how they all work together. Also there are other cummins guys on here that are way smarter than me that hopefully will chime in and be of some better help.

  3. #3
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    Not quite what it does. I?ll try to put up an explanation later today

  4. #4
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    Quote Originally Posted by Jim P View Post
    Not quite what it does. I?ll try to put up an explanation later today
    Ok thank you! been trying to read and gather as much info as possible, its definitely a big learning curve

  5. #5
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    Are they elevation based tables?

  6. #6
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    I have been working at it some more.. seems to run good, but there is one spot in the map about 2900rpm where the timing goes from 22* down to 10* for a split second. then ramps back up to 22*

    This is the log showing the drop in timing

    tune 2.hpl

  7. #7
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    Quote Originally Posted by JaegerWrenching View Post
    Are they elevation based tables?
    It's air density based, set by the air density select table. Majority of the time for majority of people it will run on the high air density table, it'll run on the transient table when there is an engine acceleration rate above a certain threshold, rpms/sec, if I remember correctly. I have logged low air density table being set before, during and after startup, switching to transient when starting to drive then switching over to high air density. If certain conditions get set in the ecm, like engine protection, it switches to low air density tables.

  8. #8
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    Quote Originally Posted by NRunkle View Post
    I have been working at it some more.. seems to run good, but there is one spot in the map about 2900rpm where the timing goes from 22* down to 10* for a split second. then ramps back up to 22*

    This is the log showing the drop in timing

    tune 2.hpl
    Whats most likely happening here is you are pulling air density down far enough that its switch air density tables for that brief moment. Make all your air density tables the same and you wont have this problem. Looking at your tune, you are taking pulsewidth too heavy into lower commanded fuel quantity. I can see why you have done that to get more power out of it but it's not going to result in a good and clean tune, you'll just end up fighting a hot smokey mess. You have fuel limiters in place that need to be altered(raised) in order to get better power.

  9. #9
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    Quote Originally Posted by Jim P View Post
    Whats most likely happening here is you are pulling air density down far enough that its switch air density tables for that brief moment. Make all your air density tables the same and you wont have this problem. Looking at your tune, you are taking pulsewidth too heavy into lower commanded fuel quantity. I can see why you have done that to get more power out of it but it's not going to result in a good and clean tune, you'll just end up fighting a hot smokey mess. You have fuel limiters in place that need to be altered(raised) in order to get better power.
    I have taken your advice and and pulled fuel and adjusted the timing.. which fuel limiters are you talking about that need to be raised?

  10. #10
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    There?s tons like boost/fuel, max fuel, lambda ratio limit(smoke limit), low boost, air density/fuel

  11. #11
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    Messed around with fueling and timing, also adjusted some of the limiters. Seems to run good to me!

    tune 2 revised.hpl