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Thread: l67 acceleration enrichment q&a

  1. #1
    Tuner Onomoto's Avatar
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    l67 acceleration enrichment q&a

    So as long as i have have this car now this problem has always been here. Under any throttle below my p.e set point 30% throttle. My wide band will show my tip in a.f.r shoot to 12ish then almost immediately bounce up to 15 to sometimes 16 afr then back to 14ish. I am attempting to get rid of the lean spike car does this anytime i get off the throttle and back on it. Trying to research info on the acceleration and transient fuel for the l67 but i can't find much. I did find a old post and adjusted the ae/tps delta the decay rate and ref counts. On my last log and flash i really just started to make big swings to see if anything would change it but i didn't notice any difference. You will see huge kr spikes about every throttle stab. Be aware i do have a header clamp smacking the sway bar.
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    Last edited by Onomoto; 10-08-2022 at 10:40 AM. Reason: typo
    2001 monte carlo swapped l67 on e85
    XP cam
    gen5 m90
    NorthStar throttle body
    speed daddy headers 3inch exhaust
    3.0 pulley
    lq4 maf
    cold air filter behind bumper
    60 lb injectors

  2. #2
    Tuner Onomoto's Avatar
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    Anyone want to chime in yet?
    2001 monte carlo swapped l67 on e85
    XP cam
    gen5 m90
    NorthStar throttle body
    speed daddy headers 3inch exhaust
    3.0 pulley
    lq4 maf
    cold air filter behind bumper
    60 lb injectors

  3. #3
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    I think it's a either a VE accuracy problem or a response problem. Only three ideas:

    1) Disable Filtered TPS for both accel and decel transients.

    2) Try SD and see what happens. Enable LTFT. Let's double-check that VE table.

    3) Verify injector data. Stock flow correct for 60lb injectors? Factory is 36lb. Zeroed Offset vs PW vs MAP?
    Last edited by SiriusC1024; 05-26-2023 at 02:20 AM.

  4. #4
    Tuner Onomoto's Avatar
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    I will give your strategy a try this weekend. All data that's in my tune file was done by a very reputable tuner in l67 business and myself have not needed to question the injector data I've have tweaked my maf curve due to a upgraded throttle body and played with the spark a little. So a couple questions I would like to ask before I start would be can you explain in better detail than the HP description about adjusting the filtered tps? And second is about the v.e table on the 3800 cars I thought were not used. I've seen the debate about that for several years now. I've always questioned the v.e side of things with the tune because when I unplugged the maf to try to adjust the v.e I can't even get the car to start.
    2001 monte carlo swapped l67 on e85
    XP cam
    gen5 m90
    NorthStar throttle body
    speed daddy headers 3inch exhaust
    3.0 pulley
    lq4 maf
    cold air filter behind bumper
    60 lb injectors

  5. #5
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    For filtered TPS the thinking is that the control math isn't reacting quickly enough. Might work might not. It's an easy thing to try.

    The MAP is there for a reason. The VE table exists. Surely it matters. Don't unplug the MAF just disable it. Accurate VE is important for transients. So is accurate injector data. Got an injector P/N?
    Last edited by SiriusC1024; 05-26-2023 at 01:39 PM.

  6. #6
    Tuner Onomoto's Avatar
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    I don't remember seeing any kinda info on the injectors when I bought them. Here is what I can find let me know it this works.Screenshot_20230526-151007.pngScreenshot_20230526-151146.png
    2001 monte carlo swapped l67 on e85
    XP cam
    gen5 m90
    NorthStar throttle body
    speed daddy headers 3inch exhaust
    3.0 pulley
    lq4 maf
    cold air filter behind bumper
    60 lb injectors

  7. #7
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    The flow rate table obviously doesn't match factory. Not necessarily a problem as long as airflow was tuned to those values, which I'm assuming it was. Changing IFR would require retune.

    Attached is a tune with Offset adjustments. Numbers are based off the manufacturer's data and converted to GM LS-style using Steck's conversion sheet. From there I converted it myself to the layout in your car's tune.

    You're welcome to it. Let me know how it works out.
    Last edited by SiriusC1024; 05-27-2023 at 01:48 AM.

  8. #8
    Tuner Onomoto's Avatar
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    Alright mr sirius i uploaded your tune and took it for a spin couple of notes.

    According to my but dyno the lite to medium throttle input felt more responsive than before. 2ND the return to idle after throttle decel absolutely felt better im guessing because of the added timing you put in. while i only drove it a little bit i noticed i didnt have as much random kr spikes ( but that could change) and that the higher maf hz needs a little more fuel but noting i cant handle. the throttle still does the same rich to lean swing but im sure that can be tweaked out. can you share what and why the injector data need adjusted from where it was? i have no problem with a consultant fee. sirius tune #1.hpl
    2001 monte carlo swapped l67 on e85
    XP cam
    gen5 m90
    NorthStar throttle body
    speed daddy headers 3inch exhaust
    3.0 pulley
    lq4 maf
    cold air filter behind bumper
    60 lb injectors

  9. #9
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    Uh what added timing? I didn't mess with spark. As far as fueling what are you trying to understand? I simply input the Deka 60 info and used a conversion sheet, as posted.

    And yes, you may need some fine-tuning to the airflow side since the injector data was adjusted.

    Also, the transients aren't going to go away until VE is correct.

    Glad it helped.
    Last edited by SiriusC1024; 05-29-2023 at 05:07 PM.

  10. #10
    Tuner Onomoto's Avatar
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    I forgot i had made a couple adjustment to the tune i put on here vs what was in the car. i had never had to input injector data in hp tuners before i am guessing incorrect injector data skews all fueling strategy.
    2001 monte carlo swapped l67 on e85
    XP cam
    gen5 m90
    NorthStar throttle body
    speed daddy headers 3inch exhaust
    3.0 pulley
    lq4 maf
    cold air filter behind bumper
    60 lb injectors

  11. #11
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    Yes.

    I've got a pretty good idea of what to do next. Got a lot going on at the moment, so I'll get back with you soon as possible.

  12. #12
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    - VE table. Corrected for difference in incorrect flow rates for injectors from the tuner. Car might start with MAF failed (MAF Fail Freq 0Hz, P0101-P0102 to Mil on First Error). If so you'll be able to tune VE more accurately.

    - Transients. Complete guess, honestly. Might try just VE, then Transients, then both, and see what happens. I think what you were overlooking when making changes was Re-Enable TPS. It's not a delta value. It's actual TPS.

    I still don't like the wrong numbers put into Flow Rate vs KPA. If it's changed you'll have to do MAF and VE from scratch.
    Last edited by SiriusC1024; 05-31-2023 at 08:46 AM.

  13. #13
    Tuner in Training Vbb1994's Avatar
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    I was one time peaking at a log and tune you posted and i noticed stoich wad still 14.6 in your vcm but the VE was increased like, 30% or something. And it seemed sort of rich at the bottom end, 60-100 kpa area.