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Thread: Calc VE Setup

  1. #21
    Joe (Moderator) joecar's Avatar
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    Brad,

    The basic concepts are like this:
    - force airmass to come from one and only one of VE or MAF;
    - from airmass the PCM determines fuelmass (from either of OL AFR, PE, CL),
    - force OL in order to prevent the PCM doing CL/LTFT/STFT corrections,
    - the BEN (wideband AFR / commanded AFR) is now the correction multiplier for whichever of VE or MAF is being used.
    - now repeat for the other airmass source.

    So, if the airmass sources have been corrected (by multiplying by BEN), then setting the target PE AFR is not raping it, it's the appropriate place to set it.


    Even on a stock LS1 car, you can get very good results by doing the AutoVE tutorial...
    on my WS6 with no mods (only 180°TS, LT headers, lid; stock catback) after correcting VE table and leaving it in OLSD, engine had very good/"instant" throttle response and my SOTP detected big improvement, engine seemed to run free-er and fuel mileage improved by a few mpg [the LT headers made it sound gooood, one quick blip in neutral changed the minds of several impromptu signal-to-signal rice racers]...

    Some people have great success (after AutoVE) by staying in OLSD, while others do not, so they run in either CLSD or do AutoMAF and run CLMAF with good success.

    However Auto VE tutorial requires effort, going step-by-step, double-checking/sanity-checking each step, and paying attention to wideband sanity (I have had the sensor itself fail on one occasion which I noticed, and when I looked at the BEN's it would have produced weird results had I not been paying attention)... Auto VE and Auto MAF take some effort and require some experience to ensure that the process is functioning correctly.


    Now, WeathermanShawn's tutorial takes a shortcut based on these points:
    - the VE table can be calculated based on MAF, MAP, RPM and DYNAIRTMP (blend of ECT and IAT to account for heat soak),
    - the MAF and/or VE provide the airmass with which the PCM calculates the fuelmass which it then trims via LTFT's,
    - so the LTFT's can be used to correct the calculated VE table,
    - the LTFT's can also used to correct the actual MAF table.

    Weatherman's tutorial can be applied with as little as one log, is very easy/simple to apply (you don't have to disable the other source of airmass, you don't have to disable CL and SOL), and seems to get good results.

    Last edited by joecar; May 1st, 2010 at 08:33 AM.

  2. #22
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    Thanks fellas! The lightbulb went on!

  3. #23
    R.I.P Shawn, 1956-2011 WeathermanShawn's Avatar
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    Thanks Joe, thats a good synopsis.

    Brad, let us know how it goes. Lately there have been more tuning challenges just with the use of a wideband (calibration, etc). I think as long as you keep all your sensors nice and accurate, tuning is a whole lot more fun.

    Since going serial connection on the wideband..I can't imagine doing it any other way. Just read up on Mr. Pricks threads on fine-tuning the wideband to get it to properly match stoich. (I think I have that right). And if you stay closed-loop, fresh O2 sensors help..

    Good luck..
    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..


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