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Thread: A real bug- pretty sure this time

  1. #1
    Senior Tuner kingtal0n's Avatar
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    A real bug- pretty sure this time

    sometime last year I had this happen and never really figured out why.

    But then it happened again and I feel like this is important enough to bring to light-
    I am sure the engine could have hydrolocked or at the very least washed down the cylinders with fuel because of this one simple thing

    See what happened
    omfg.png

    When it hits PE, it goes insanely rich. Commanding 0.5 EQ ratio. Injector duty goes full open the engine coughs and dies flooded.

    I tracked it down to the table "IAT adder" for PE enrichment. The table suggests you can use any value from -2 to 2.0
    Pic of table responsible:
    table.png

    Well, don't try the negative numbers! I pulled about -.005 and the negative must do something to the fraction EQ ratio .... it commanded 7:1 and later 0.5:1 as above! (400% duty cycle)

    Operating system is 125 "2-bar"
    411 ECU gen3
    Last edited by kingtal0n; 10-21-2019 at 09:47 PM.

  2. #2
    Can you post the tune it had when it occurred and the log of it happening? It has done it twice at random? Seems odd that it would be tune related if it has only done it twice.

  3. #3
    Senior Tuner kingtal0n's Avatar
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    Quote Originally Posted by Sith View Post
    Can you post the tune it had when it occurred and the log of it happening? It has done it twice at random? Seems odd that it would be tune related if it has only done it twice.
    Okay sorry if I wasn't clear

    The first time it happened, I just uploaded an old tune to 'fix' the problem. I never tracked down which table was causing it. But I knew it was something in there.

    Then a couple days ago I made the same change to the same table and the problem came back. This time however I simply compared my OLD (from years ago) "bad" file with the "fixed" files to narrow down which table was causing the problem.

    If you wish to repeat the issue simply put a negative number into the IAT adder for power enrichment on a 2-bar OS w/ 411 computer presumably

  4. #4
    Ah ok. That makes more sense.

    Power Enrich EQ Ratio: This is the main table that is used to tune WOT fuel. The values in this table are Fuel/Air multipliers (or Equivalence Ratio) ie. values greater than 1 are richer, values less than one are leaner. The values relate directly to the Stoich AFR and the resulting commanded AFR is Stoich divided by this PE multiplier. Eg. if the multiplier is 1.1 then the commanded AFR will be 14.7/1.1 or 13.36.

    Power Enrich Fuel IAT Adder: This table adds to the PE multiplier in relation to inlet air temperature (IAT).

    By my understanding if the PE commanded multiplier is 1.1, the IAT adder add between -2/+2 from the 1.1 multiplier based on IAT? So 14.7/1.1 could changed to 14.7/1.2 if the IAT adder was .1?