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Thread: Calc.VET: correcting MAF and calculating VE (in single log)

  1. #691
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    Hi

    I have a 03 Silverado 5.3 Im in the process of supercharging. Ive installed headers and exhaust. Upgraded fuel system. As I struggle a bit learning EFI Live Ive not installed the supercharger itself, and are using stock injectors and fuel pressure.

    As I have problems quoting text from the summary notes(norwegian character set seems to do strange things). I will just copy some of the text.

    ------
    6. B3616: PE Enable: make sure PE enables as load becomes significant
    (e.g. below 60% TP below 3200 rpm, 35% TP above 3200 rpm).
    -------

    After reading this, my understanding is that PE should be used for all significant loads.

    -------
    PE Mode/WOT:

    PE Mode is best performed utilizing 100% TPS (WOT). This is because a number of Fuel Dynamic Parameters are kept steady and constant (evaporation, cylinder wall-wetting, etc). Also, a steady 100% TPS insures accurate computation of the MAF Airflow. Avoid part-throttle PE Mode Tuning.
    -------

    But after reading this later text, my understanding is that PE is only for WOT. Whats correct?


    Then I somwhere read that high postetive fuel trims are no good. Since mine are pretty high, I do not know what to do. Please se attached screenshot .
    Click image for larger version. 

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    Last edited by EspenT; May 8th, 2017 at 06:04 PM.

  2. #692
    Joe (Moderator) joecar's Avatar
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    Hi ET,

    Quote Originally Posted by EspenT View Post
    ------
    6. B3616: PE Enable: make sure PE enables as load becomes significant
    (e.g. below 60% TP below 3200 rpm, 35% TP above 3200 rpm).
    -------

    After reading this, my understanding is that PE should be used for all significant loads.
    -------
    PE Mode/WOT:

    PE Mode is best performed utilizing 100% TPS (WOT). This is because a number of Fuel Dynamic Parameters are kept steady and constant (evaporation, cylinder wall-wetting, etc). Also, a steady 100% TPS insures accurate computation of the MAF Airflow. Avoid part-throttle PE Mode Tuning.
    -------

    But after reading this later text, my understanding is that PE is only for WOT. Whats correct?
    Yes, correct, WOT.


    Then I somwhere read that high postetive fuel trims are no good. Since mine are pretty high, I do not know what to do. Please se attached screenshot .
    Click image for larger version. 

Name:	Screen Shot 2017-05-08 at 11.55.46.png 
Views:	216 
Size:	227.5 KB 
ID:	21039
    Yes, correct, high positive trims indicates that the MAF and/or VE tables are under-calculating the cylinder airmass.

    If you isolate the MAF (i.e. disable VE by setting B0120 to zero) you can use the trims to correct the MAF table.

    If you isolate the VE (i.e. disable MAF by causing a MAF DTC) you can then use the trims to correct the VE table.
    Last edited by joecar; May 9th, 2017 at 04:25 AM.

  3. #693
    Joe (Moderator) joecar's Avatar
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    Hi ET, something happened to your screenshot, can you please post it again.

  4. #694
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    Uploaded a new screenshot in the post above.

    Here is the complete log.
    The tune is the stock tune from the car except the changes in the summary notes.

    Log_1GCEK19T53Z287757_0000.efi
    Last edited by EspenT; May 8th, 2017 at 06:18 PM.

  5. #695
    Joe (Moderator) joecar's Avatar
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    Post your tune file.

  6. #696
    Joe (Moderator) joecar's Avatar
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    Looks like you're running lean, can you hear it knocking...?

  7. #697
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    Yes.. Its way leaner than I would like. Except when in PE mode. Cant hear the ping, but I see knock on the logs.

    Here
    Attached Files Attached Files

  8. #698
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    Used the ltftben from the first log and made adjustments to the maf calibration. logs now show close to zero ltft No more knock retard

    Click image for larger version. 

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    Tok another drive/log and did some adjustments to main ve. Probably need some more logging/smoothing. But does it look reasonable ?
    dk61031_calcVET_0002.ctz

  9. #699
    Joe (Moderator) joecar's Avatar
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    Quote Originally Posted by EspenT View Post
    Used the ltftben from the first log and made adjustments to the maf calibration. logs now show close to zero ltft No more knock retard

    Click image for larger version. 

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    Good job

    Tok another drive/log and did some adjustments to main ve. Probably need some more logging/smoothing. But does it look reasonable ?
    dk61031_calcVET_0002.ctz
    VE looks quite good (did you use LTFTBEN...? did you disable the MAF when adjusting the VE)...?


    I don't know how high your engine revs, but for safety bump up the VE table from 5200 thru to 6400 or 6800 rpm.

  10. #700
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    Quote Originally Posted by joecar View Post
    Good job

    VE looks quite good (did you use LTFTBEN...? did you disable the MAF when adjusting the VE)...?


    I don't know how high your engine revs, but for safety bump up the VE table from 5200 thru to 6400 or 6800 rpm.
    Thank you

    I followed the Calc VET tutorial to calculate the VE table. Used "Calculated VE, BEN corrected (g*K/kPa)" so the VE is calculated with data from the MAF ?

    My next step is to disable MAF and se how the engine would run on the VE table. But due to some unexpected snow I will need to wait for the roads to dry up.
    Click image for larger version. 

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