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Thread: Tune Hiccup - VE Airflow / Dynamic Airflow Momentarily Drop to 0???

  1. #1
    Potential Tuner MacWerks's Avatar
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    Unhappy Tune Hiccup - VE Airflow / Dynamic Airflow Momentarily Drop to 0???

    Hi all -
    Been lurking for a while, and finally am getting my 6 year project on the road..

    Engine's a de-stroked, high compression, high-revving E85 build. 6.3L, 4.125" Bore, 3.622" stroke.. NC ported heads and big cam (BTR 33954143, 239/254 .624"/.595" 114+3). Intake is a ported LS3 piece (chokes it), and exhaust is a full 2" primary long-tube setup with dual 3.5" out (includes an X-pipe). Static CR is somewhere around 13.3:1.

    I'm running an E67 ECM with the '07 CTS-V O.S. (12609051) due to some of the other vehicle/swap requirements.

    This is the first engine I've ever built and tuned, and so far things have been working along nicely and this thing's a ripper.. EXCEPT, the damned thing hiccups in the mid/upper RPM band with partial throttle (most of the time) .
    Managed to isolate one good sample of the event in the attached log file centered at 00:00:37.941. Event starts around 00:00:37.864 and finishes around 00:00:38:015.

    The dynamic airflow / VE airflow inexplicably hits zero, and quickly recovers. Events seem to be isolated to 3K rpm or higher, and mid to upper load, but I don't understand enough about the issue to be able to trend when/why it'd otherwise be happening..

    Would love any sort of insight as to whether this is a boundary calculation issue from the VE or perhaps it's a zone boundary calculation issue as the cam really comes alive... Not sure.. at a total loss. I've even tried looping the VVE stuff through Bluecat to attempt to let it auto-manage zone boundaries, but it seems to slap some of the zones REALLY close together (don't have a level of confidence in this yet).

    Attached the tune / log and hoping someone can provide some love! I can also include a general driving tune if someone would like to see more data outside of a very isolated event.

    Cheers!

    Wagon-Tune-070420.hptHiccup.hpl

  2. #2
    Senior Tuner
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    if ur SD operation set the dynamic airflow low to 8000, keep high where it is, and the maf fail high/low set to 2/1, set high/low counts to 1, set the ecm 4040 to max and 4041 to min values to stop the tests, set the ecm 4042 tests from 800 to 8000rpm so it disables those tests see if any of that helps, if u have a manifold vacuum referenced fuel reg u need to change the offset v press v volts table to suit as u have the IFR flat lined or u should have the IFR to suit static fuel pressure if u are setup that way, your eoit normal ect table is adjusted in a strange way advancing injection alot

  3. #3
    Potential Tuner MacWerks's Avatar
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    Reviving this one a little bit for some further discussion -

    Worked through the tweaks that 07GTS suggested, but the issue is persisting. I'm starting to suspect that it's an artifact of the SD tune and a transition across a zone boundary border..
    Anyone have any good guides for how one should tune/adjust the zones? I had initially used bluecat's tool, but I don't have enough data to show that it's good, bad or otherwise though the zones are definitely different than where I started.. (Zones should be same as current in the prior attached file).
    '03 BMW 325 Wagon = Rowdy 6.3L screamer

  4. #4
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    try the boundaries like this see if it helps at all it should still stay good once coefficients are calculated