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Thread: getting knock under wot

  1. #21
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    Quote Originally Posted by smasher View Post
    oh ok I guess I'm confused on how the injector table is used then. I took the data out because it didn't run correctly when I put the data I there. I believe someone said the only thing that matters is if it has a vacuum to determine which data table to use because one says return less and the other says. I'm not trying really to be difficult just trying to learn but wouldn't you use the bottom one?
    I skimmed back through this and don't see much of a description of your fuel system. Maybe you should clarify that.

  2. #22
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    Ok so I found the "corvette regulator filter?". If that is your set up, you have a constant 58psi non referenced system. Or at least you hope it has 58psi depending on the quality of the regulator.

  3. #23
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    ok sir here is another file no knock. I suppose the order in which you have to do things is to clean up the fuel trims up, then the ve table, and then adjust for spark, I guess its ok to leave it lean down low in the rpms. Also, I see what you're saying as far as the injector table goes and it makes more sense with it being the other table than the one I choose i was basing it off the vacuum line. also, on injector pulse width why .76 instead off .243 like the data sheet?
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    Last edited by smasher; 09-11-2024 at 08:07 PM.

  4. #24
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    Quote Originally Posted by smasher View Post
    oh ok I guess I'm confused on how the injector table is used then. I took the data out because it didn't run correctly when I put the data I there. I believe someone said the only thing that matters is if it has a vacuum to determine which data table to use because one says return less and the other says manifold ref. I'm not trying really to be difficult just trying to learn but wouldn't you use the bottom one?
    You use the top one. With no vacuum reference the pressure isn't maintained across the injector. Corvette reg supplies a constant 58psi at the back of the injector. Manifold vacuum adds to the total differential pressure, so that's why IFR increases.

    As far as being difficult...nonsense. There have been difficult people on here from time to time, but it's totally ok to have questions about what I'm doing with your setup.

    Now I'll explain why I didn't use the Minimum Injector PW from that file. First apply logic. Why do those tables exist? Why command a minimum at all. It must matter.

    The minimum PW table exists as a floor for transients. 0.243ms is a really short time, especially compared to the stock injectors. Sure, it's an updated design and physically reacts faster, but there's more to it than that.

    A rapid tip-in event occurs, the ECU makes a prediction based on the dynamic airflow model, derived from MAF, VE, and transient fueling tables. The ECU has only so much resolution in terms of processing power. There's a point where the model doesn't match reality. Error increases as interval decreases. That file is converted Gen IV data. Gen IV ECU's are much faster than Gen III.

    I set the MinPW floor, or left it where you had it anyway, so that if there is an error in the predictive model during a transient that results in a lean condition then it is overridden.

  5. #25
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    That makes a lot of sense to me. Is that because of the 58tooth reluctor that its able to process faster and maybe a faster pcm? So where do I go from here? Is it still in sd mode? is there anything left that needs adjusted? I just seen your post about the wrong sensor I can run another log.
    Last edited by smasher; 09-11-2024 at 10:01 PM.

  6. #26
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    Doing a lot better on return to idle isn't it?

    Look at the y-axis of the spark tables. Cylinder Airmass. That value comes from the airflow models. Accurate injector data, accurate airflow model, accurate spark.

    Need cam specs, diff ratio, tire size, spark plug type.

    Install a wideband and get it logged. This type of build and the shaping of the VE table I'd feel better with some verification up top.

    Log TPS voltage, and pretty please...B2S1?
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  7. #27
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    Definitely idles better. it actually runs amazing. Its lots of fun. I got my wideband in the other day just haven't put it on yet, I'll try and stick it on tomorrow. it's a comp cam 54-459-11 231/239, 3.73 diff, NGK 1465 iridium plug I believe it has a heat range 5. Tire size is 275/50/20. I did 2 parts of this log ever once in a while the scanner likes to stop working on me. looks like that kr is back
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    Last edited by smasher; 09-12-2024 at 12:04 AM.

  8. #28
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    Get some NGK TR6's in there for sure. You're still clearing LTFT's between tune uploads I hope. What speed stall?
    Last edited by SiriusC1024; 09-12-2024 at 12:00 AM.

  9. #29
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    2800 stall speed. I think I cleared them on the first part not the second after it messed up. just curious why I'm constantly clearing those?
    Last edited by smasher; 09-12-2024 at 12:21 AM.

  10. #30
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    Highly recommend 6 heat range iridiums - NGK TR6IX. It appears that it gets more knock prone the harder it's ran.

    Compensated for now. Lowered spark and bandaided with PE. When those plugs come in we can start bringing the spark back up.

    Good for now until plugs and wideband.

    Clear LTFT's because they are stored trims. When a new tune is loaded with a new airflow model it needs to start from scratch. LTFT's can stay between revisions.
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  11. #31
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    I reran another log and no knock I cleared ltft. I haven't uploaded the one above this comment this is the one that the scanner was messing up.
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  12. #32
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    Right. It's been sitting at least an hour and the parts aren't heat soaked. See what I mean? TR6IX.

  13. #33
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    yes sir now i completely understand lol. But what's the deal with the clearing of the ltft

  14. #34
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    What do you mean? LTFT's are persistent. Just because a new tune is loaded doesn't mean they clear. If a new airflow model is part of a tune that's uploaded then all corrections need to be zeroed out. Otherwise you'll have to wait, sometimes a while, for LTFT's to be brought back inline.

    I like LTFT's because they are a rolling average. LTFT's make for more accurate STFT's because the margin of error is smaller. STFT builds through proportional-integral to stoichiometric. Like any PI controller there is gain to think about.

    When tuning, I use LTFT, STFT, and LTFT+STFT when doing VE and MAF.

  15. #35
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    ok I see what's going on. I didn't really put much thought into it. New tune different trims. Instead of waiting for the trims to average out from an old tune.
    Last edited by smasher; 09-12-2024 at 03:23 AM.

  16. #36
    Quote Originally Posted by SiriusC1024 View Post
    Highly recommend 6 heat range iridiums - NGK TR6IX. It appears that it gets more knock prone the harder it's ran.

    Compensated for now. Lowered spark and bandaided with PE. When those plugs come in we can start bringing the spark back up.

    Good for now until plugs and wideband.

    Clear LTFT's because they are stored trims. When a new tune is loaded with a new airflow model it needs to start from scratch. LTFT's can stay between revisions.
    This plugs help with WOT knock?

  17. #37
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    Yes.

  18. #38
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    Was wondering if I can use some av gas which is around 108 octane. Currently waiting on a Prolink cable for the wideband. Also, I was wondering if that means my engine is higher compression than configured to be?
    Last edited by smasher; 09-13-2024 at 10:48 PM.

  19. #39
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    Even "low lead" avgas will quickly ruin your o2 sensors.

  20. #40
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    It's pretty much common knowledge to use TR6's on a cammed up LS. Let's see what happens before being boxed in to specialty fuel. As far as that goes, I prefer E85.