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Thread: airflow gain

  1. #1
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    airflow gain

    Thought I was getting somewhere understanding pe and be and then someone posts a snapshot of the airflow gain table and puts me back into confusion. Is this table a way to use pe and map vs rpm and ignore the be table for boost?

  2. #2
    Senior Tuner Google's Avatar
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    set your PE as though you have no boost or for a N/A setup. then set your BE for enrichment of boost or over 110kpa. the computer will use the richer of the two. that way if your power adder fails you don't run to rich and can still drive your ride home. and if your power adder fails you won't see the map area that BE is setup for.

    think i said that right.

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    Quote Originally Posted by Google View Post
    set your PE as though you have no boost or for a N/A setup. then set your BE for enrichment of boost or over 110kpa. the computer will use the richer of the two. that way if your power adder fails you don't run to rich and can still drive your ride home. and if your power adder fails you won't see the map area that BE is setup for.

    think i said that right.
    check thread ' 2 bar Boost enrichment ' by Bottle Fed in Gen 3

  4. #4
    Senior Tuner Google's Avatar
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    ya that thread sounds the same as i discribed. use be to keep from going lean if the waste gate sticks shut. more air then pe can handle be is richer and the pcm will take the richer be and use it.

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    Quote Originally Posted by Google View Post
    ya that thread sounds the same as i discribed. use be to keep from going lean if the waste gate sticks shut. more air then pe can handle be is richer and the pcm will take the richer be and use it.
    Okay another comment about the safety of BE-last one was from Bill and no explanation why PE vs using BE to control all fuel when in positive manifold pressure. Is my question not clear.
    Why tune boost afr into areas below positive manifold pressure when you have a be table?
    Last edited by backchannel; 09-21-2010 at 09:43 AM.

  6. #6
    Senior Tuner 5_Liter_Eater's Avatar
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    Question is not very clear. BE only takes over after 105 pKa. It will always use the greater of PE and BE.
    Bill Winters

    Former owner/builder/tuner of the FarmVette
    Out of the LSx tuning game

  7. #7
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    Quote Originally Posted by 5_Liter_Eater View Post
    Question is not very clear. BE only takes over after 105 pKa. It will always use the greater of PE and BE.
    There has been comment about using pe for fueling boost and that the be table is for safety if you boost higher. Since this was said by someone in the know and I got a tune[ from an expert] with pe at 1.30 and be at 0, it doesn't make sense to me. What I don't get is why not use pe for neg. manifold pressure fueling and be for positive manifold pressure fuel. I do this and its much cleaner that using the pe table only.
    thanks for responding

  8. #8
    Senior Tuner 5_Liter_Eater's Avatar
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    Thats what I do. I think there were reports early on that BE was not kicking in fast enough or something but I have never had a problem. I find that I am rarely ever in PE. I go right from closed loop to BE.
    Bill Winters

    Former owner/builder/tuner of the FarmVette
    Out of the LSx tuning game

  9. #9
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    Quote Originally Posted by 5_Liter_Eater View Post
    Thats what I do. I think there were reports early on that BE was not kicking in fast enough or something but I have never had a problem. I find that I am rarely ever in PE. I go right from closed loop to BE.
    nothing wrong with a heavy foot.

  10. #10
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    I have to bring up this thread as I am trying to get the Fuel tab> Open&Closed Loop> Airflow Gain table to work in my E38 ECU. Was this thread about using 2BAR custom OS only? It looks like this Airflow Gain table should be usable on the stock OS but it's not working for me. That table is said to be a EQ multiplier but I tested it by setting my normal PE table to 1.00 and the Airflow Gain table to 1.27 but it didn't get rich when I jump on the gas and boosted up.

    So I'm thinking it ether doesn't work at all. Or maybe it's because I have my LTFT's off. Or maybe because I have Dynamic Airflow off.
    Please help, I really really want to use some progressive PE on this car. Thanks guys.

  11. #11
    Senior Tuner DSteck's Avatar
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    PE/BE will override open loop fueling. It doesn't pick the richer of the two.

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    So are a bunch of the above posts incorrect? That's even more confusing.
    You're saying it would work if I could trigger open loop without triggering PE. Isn't triggering open loop the same thing as triggering PE?

    Or does open loop not need triggering and all I have to do is set it to never enter PE?
    Last edited by C5turbo; 09-30-2012 at 11:37 PM.

  13. #13
    Senior Tuner DSteck's Avatar
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    Run the car in open loop and pick set criteria that ensures you never meet PE/BE requirements. Then you can use the airflow gain table.

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  14. #14
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    Is it possible to keep closed loop up to a point and then have it go open loop? Cause the only way I can see the open loop Airflow Gain table being usable, would be to turn closed loop off completely.

  15. #15
    Quote Originally Posted by DSteck View Post
    PE/BE will override open loop fueling. It doesn't pick the richer of the two.
    Quote Originally Posted by DSteck View Post
    Run the car in open loop and pick set criteria that ensures you never meet PE/BE requirements. Then you can use the airflow gain table.
    Is there any known was around this? Ideally for me, the ECM would run in closed loop until a certain parameter (or parameters) is met (the Power Enrichment parameters would work perfect) then be able to use these open loop gain tables to control pulse width based on MAP and RPM. The PE EQ ratio table is so limited in comparison... Ugh.

    Is there is a way to use the richer/higher of the two values vs forced to use PE? Seems so simple... But i know its not.