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Thread: Tuning Notes by WeathermanShawn

  1. #121
    Senior Member acomp917's Avatar
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    Hello All,

    I don't mean to reiterate the same thinking, although i have just gone through the report for a 12212156 and I must beg the differ. Assuming that you are not tuning a stock vehicle, you must:

    Throw in a reasonable timing map.
    Get rid of as many variables as possible. http://forum.efilive.com/showthread.php?t=13021
    Make sure the torque limit and traction control are disabled.
    Set all of the changed hardware parameters.
    Get car to idle(somewhat).
    Use WBO2 and some method of applying changes(I prefer filtered) to: VE/IFR/MAF

    After getting things close, go to dyno(steady state if possible) and setup the timing table. Start all over with fine tuning the AFR.

    What gets me about many of these posts is: They reflect government politics... "We know what were doing, don't ask for specifics, you would not understand them anyway".

    I say, watch the WBO2, watch for knock, and don't pin it's ears back for too long until you can make sure the first 2 are OK. This is not a trip to the moon, it's just wasting gasoline. Like anything, the better you get, the less waste you will create.

    My 02,
    S

  2. #122
    Lifetime Member 5.7ute's Avatar
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    Quote Originally Posted by WeathermanShawn View Post
    To this date I still have not seen any published material on the exact amount of airflow correction and resulting fueling adjustment when using the GM MAF/SD hybrid. You know it does it..but how much, and does anyone know the exact amount for every RPM and MAP.
    Yep, but its top secret.
    Seriously though Shawn, you have the tools at your fingertips to work this out.
    Log {GM.DYNCYLAIR_DMA} & {GM.CYLAIR_DMA}. This will show you the airmass the PCM is seeing in both modes.
    {GM.IBPWx},{GM.AFR}, {GM.INJFLOW},{GM.MANVAC}& {GM.VOLTS} + whatever conditions you want to log.RPM,MAP etc.
    There is some tricky maths(for me anyway) but you can back calculate a fair bit from these pids. FI Airmass = (IBPWx-{B3701})*{GM.INJFLOW}*{GM.AFR}
    If you want precision you need to make a calc pid for AFR,IFR,Airmass etc. This works quite well.
    *CLC-00-001
    G/cyl 0.0 2 0.6 "{GM.DYNCYLAIR}"

    CALC.DYNCYLAIR F001 CLC-00-001 G/cyl Fuel "Calc Cylinder Airmass"
    Do this for all the pids you need to get precision to 6 decimal places.
    Any differences will soon become apparent & this process can be used for transient fuelling additions, offset calculations etc etc.
    The Tremor at AIR

  3. #123
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    Quote Originally Posted by WeathermanShawn View Post
    I totally understand and accept your point. Tuning involves a lot of 'moving targets', and you are right it must be considered as a system.

    I still think there is a lot of wisdom in RevGTO's comment..

    If at the end of the day your AFR's are as commanded and your LTFT's are in order, you've gotten your airflow tables pretty close to correct.


    If we can get everyone to agree to that, we will call it a truce.
    no truce. In order to correctly assess the goodness of your AFR, you must start out by creating a metric that isn't averaging errors on both sides of the stoich. You do realize I hope that if you have a 1000 frames of -10% error and another 1000 frames of +10% error, your BEN will tell you it's perfect, right? Most errors tend to follow the Gaussian distribution, so averaging a large enough of a sample, will tend to result in a 0. That does not mean that your tune is anywhere near decent. Until you fix that, you're looking at meaningless results.

    And as far as RevGTO's comments, you're doing it backwards. You can't justify the means with results, that's not how to you do science. You formulate a theory, you gather data, you see if the gathered data is inconclusive, proving, or disproving your theory. And the last part is a lot more involved than you think. Like I've mentioned in the previous paragraph, you must make sure your metrics make sense for the data you're working with. BEN is clearly wrong, so stop using it. Data analysis consists of not just looking at how well the data fits, but how are the errors distributed. If the errors are not distributed normally, if they have a pattern of their own, then your initial model is not a good fit, and you start from the beginning.

  4. #124
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    I think that Shawn is doing exactly what Marcin proposes: He has formulated a theory, tested it, and is in the process of trying to account for and compensate for all the variables that affect the system. But at a certain point, it becomes like climate change theory - you simply can't account for and factor in all the variables.

    Let's get back to the brass tacks. We are involved in this because we have modified our engines' airflow with intakes, headers, cams, etc. As a result, our fueling is wildly off with the stock tune. While we may not be able to get it PERFECT, we do need to get it close.

    Shawn's results speak for themselves. Reverse engineered or not, his fueling is reasonably accurate. Plus his method is simpler than previous approaches. It would be a mistake not to publish because of theoretical concerns about purity of method.

    Until Marcin translates his knowledge of the system into a applicable tuning protocol, we have to do our best with other approaches, because we need to get our cars to run as well as they can. Please go ahead with refining your process and publish, Shawn.

  5. #125
    Senior Member acomp917's Avatar
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    here I go again,

    I refuse to let fisherman use the swingin bait to ruin what appears to be honest attempt to help others.

    Sure there are dynamics in engine tuning. That should make it clear to the scientists that "absolutes'" when applied to transients are NEVER going to be perfect. After all, the engine is suppose to make a constant pull in order to accelerate a mass or maintain velocity. Any transient is just the tuners attempt to get it there.

    MAKE NO MISTAKE! The MOST difficult tuning parameter to perfect(for average tuners) is "applied" timing(what the engine sees). There can be many(or few) variables. You must keep in mind that AFR is affected by timing. The only way to have PERFECT applied timing is to use a dyno(real TQ) or map cylinder pressure vs. crankshaft degrees(theoretic- max. pressure vs position(aft. TDC)). My recommendation is to apply a more aggressive timing (both slope and offset(learn this, it is used for many principles)) than GM uses. When you get familiar with timing you will notice it takes on the appearance of cam(contour)/compression ratio/fuel(offset)/vehicle use(slope) and to some degree vehicle weight and gear ratio(transient). These ALL apply to cylinder pressure(filling) and to a reasonable degree how long a given state is maintained.

    When you get the timing setup(usually will not be the first), setting the fuel is easy. Map KR vs. (RPM, dyncylair), make sure you don't have knock. BAD knock will show on the plugs as aluminum deposits from the pistons. KR is VERY safe at the lower limits. Just remember that a modified engine might throw KR even if it is NOT experiencing detonation.

    I plan on attempting to use some very old math skills to help interested users in the future. I know how engines and EFI work, now if I can just re-learn the math. This EFIL system is truely monumental(as far as my limited skills).

    S

    PS. RHS(aka Marcin) is a VERY technical mind. I think that his thought process has it's place. I just think he uses it egg members on. I wish he would reference created examples that attempted to show members how to apply his "hi" thinking to engine tuning.

  6. #126
    Lifetime Member mr.prick's Avatar
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    You are acting like perfection can be achieved.
    If it could LTFTs/STFTs would not exist.
    Remember that the LS1 controller is being used.
    Maybe w/VVE perfection is obtainable but not here.

    How about explaining why commanded EQ differs from what is defined by {B3601}.
    I've logged a difference in commanded EQ as much as 0.003EQ during PE,
    that's 0.04389AFR leaner than what {B3601}/{B3618} would command. :confused

    I think there are a lot of things going on in the PCM/OS that most if not
    all people do not take into account or even have access to while tuning.
    512k RoadRunner Firmware 12.14R
    FlashScan V2 Bootblock V2.07.04 Firmware V2.07.22 EFILive V7.5.7 (Build 191) V8.2.1 (Build 181)
    LC-1 WBO2

    _________________________________________________

  7. #127
    Senior Member acomp917's Avatar
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    Mr. Prick,

    DajaVu, Maybe I haven't been around long enough.

    I had this exact reaction in the Lt1 forum years ago.


    About that error: 0.04389AFR leaner

    I don't know what we are gonna do!!!

    Now if some genus would tell me how to map DYNCYLAIR into a spark map... I would understand the missing link.

    Best Wishes, No politics intended
    S

  8. #128
    Lifetime Member mr.prick's Avatar
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    Quote Originally Posted by acomp917 View Post
    Mr. Prick,

    DajaVu, Maybe I haven't been around long enough.

    I had this exact reaction in the Lt1 forum years ago.


    About that error: 0.04389AFR leaner

    I don't know what we are gonna do!!!
    Yeah I know BFD it's just 0.04389AFR.
    But it's something to consider if you're striving for perfection.
    The PCM won't even command what you want it to.
    512k RoadRunner Firmware 12.14R
    FlashScan V2 Bootblock V2.07.04 Firmware V2.07.22 EFILive V7.5.7 (Build 191) V8.2.1 (Build 181)
    LC-1 WBO2

    _________________________________________________

  9. #129
    R.I.P Shawn, 1956-2011 WeathermanShawn's Avatar
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    Thanks for the support.

    I still plan on updating the Draft Proposal on "A Beginners Guide To Tuning", CALC.VE Tuning Guide in the next week, before handing it off to TAQuickness for editing.

    I personally like the concept of using BENS and Calculated PIDs. I think it greatly enhances the use of EFILive software, and makes tuning enjoyable. We all know where everybody stands on tuning philosophy, so I will let the readers ultimately determine what method(s) to use.

    There is still be future work to do in incorporating the role of ECT in SD airflow calculations, but we can't let perfection get in the way of progress.

    Look for future updates in the next week!
    Last edited by WeathermanShawn; February 19th, 2010 at 12:13 AM.
    2002 Black Camaro Z-28 M6 Hardtop 11.0:1CR 425HP/410TQ SAE (400TQ@3500RPM)
    200cc Heads, 228/232 110+2 Cam, 1 3/4" LT's w/catts, GMMG, Koni Shocks, Hotchkis Springs, 35/21 Sways, 17" ZR1's, 3.90 Gears Roadrunner PCM LM-2 Serial Wideband
    EFILive Closed-Loop MAF/SD Hybrid Tune..


  10. #130
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    Quote Originally Posted by acomp917 View Post
    PS. RHS(aka Marcin) is a VERY technical mind. I think that his thought process has it's place. I just think he uses it egg members on. I wish he would reference created examples that attempted to show members how to apply his "hi" thinking to engine tuning.
    Until Marcin translates his knowledge of the system into a applicable tuning protocol, we have to do our best with other approaches, because we need to get our cars to run as well as they can.
    Your complaints are noted. To me, after putting together 'three airmass model' all calibration became self-evident. Apparently you don't see it the same way. Now that I know there's a disconnect between my writing and perceived insight from reading it, I know there's more writing to be done. That's something I can definitely work with.

    How about we cut a deal? I will write my stuff up in small, hopefully easily digestible installments. After each piece, YOU will comment, correct, ask for clarifications, expand on this, stop repeating yourself over there sort of collaborative editing. Once you're satisfied, I will move on to another section, until we're all satisfied.

    Deal?

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