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Thread: Fuel dynamics mafless?

  1. #41
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    Quote Originally Posted by swingtan View Post
    I'v e been looking at dynamics a bit more and found another interesting point.

    When running CL, if you get a large rich spike on throttle close, the O2's will pull a massive amount of fuel to bring the AFR's back to where they should be. If you then snap the throttle open again, you get a huge lean spike, as the O2's have pulled all the fuel out.
    What sort of time frame/load? Any logs of the lean/rich spikes? Have found similar quick throttle opens under no load to give a rich blip followed immediately by a lean blip then of course back to L=1.

  2. #42
    Lifetime Member mr.prick's Avatar
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    OS 12212156/LS1
    I know this is a GENIV thread but I figured the dynamics stuff works the same.

    The thing I worry about is if I change impact or evap what will this do to MAF/VE?
    LTFTs and WOT are good I don't want to change impact and/or evap then have to mess w/VE and/or MAF.
    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

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  3. #43
    Lifetime Member swingtan's Avatar
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    OK, here's a few images of the dynamic overshoot....

    Commanded AFR remains at stoich.

    This was a take off from a stand still and shows the shifting up through the gears. The rich spike on throttle close is causing a subsequent lean spike on the next throttle opening.



    Commanded AFR tranition to / from PE

    This shows the transition to / from PE with throttle change. Again this was a take off and shows the overshoot getting worse.




    Throttle Blip

    This shows the results with throttle blips. Blips will always cause issues due to the rapid change in engine conditions.




    Simon.

  4. #44
    Lifetime Member mr.prick's Avatar
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    How is the intake valve temp measured?
    Can it be calculated based off ECT?
    All the dynamics stuff for GENIII are based off ECT.
    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

    _________________________________________________

  5. #45
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    Quote Originally Posted by mr.prick View Post
    How is the intake valve temp measured?
    Can it be calculated based off ECT?
    All the dynamics stuff for GENIII are based off ECT.
    Its a mix of load, ECT, run time, fuel type. And maybe more...but those items do influence it.

  6. #46
    Senior Member auspeed's Avatar
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    This was an interesting read.... now 6 years later are the findings/theories still the same for modifying dynamics?

  7. #47
    Junior Member rich24v's Avatar
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    Also more than a vested interest since I have a SD maffless tune which "feels" better in OL rather than CL.....and am noticing some of the observations within this thread. Has a path been found for getting transients working without MAF ?
    UK spec 2009 HSV VXR8 6.2 LS3, E38, HeartBeat Supercharger running ~9psi,1 7/8" long tubes, cat back exhaust.
    Upgraded cam and springs of unknown specification, all I know is, it's a small cam with no overlap, suits the s/c.
    ATI damper, LS9 twin plate clutch, 548rwhp. twin PLX widebands to twin gauges.
    Currently running dismal HPTuners....NOW DUMPED !, Completed migration to EFIlive and slowly mapping it in.
    628rwhp.....with a lot of tuner help

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