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Thread: Dynamic Airflow Transition Lean

  1. #1

    Dynamic Airflow Transition Lean

    Ok. I must be missing something here. Or I can't do what I want....
    When running blended airflow, setting dynamic disable to 3000rpm, I get a lean condition from initial WOT to the transition at 3000rpm.
    If I run pure MAF, there is no lean condition. If I run pure VE, then also no lean condition.

    It's like I'm hitting a VE Maximum value, similar to the E40 ECU. But I can set those. I've found nothing in this E67.

    Dyno 7 shows the lean condition. Dyno 5 shows SD mode.
    I artificially bumped up the MAF values in the transition area to try and dampen the lean condition. So, I know those values can't be right. Was just trying it.

    Any advice?

    Dyno 07.hplMAF 02.hptDyno 05.hpl

  2. #2
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    Did you try moving it to another RPM point (while keeping it enabled)?

  3. #3
    Yeah, I've moved it. The lean condition follows the switching RPM. If I raise the RPM, it will be lean longer, and vice versa.

  4. #4
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    I can't see the tune. I'm not on beta. Sorry. I definitely see what you're talking about though.

  5. #5
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    What happens if you change your enrichment ramp in to something like 1.5? Interesting it doesn't do it on each individually but does when combined, because that really sounds like the SD is off just from the base description?
    2010 Vette Stock Bottom LS3 - LS2 APS Twin Turbo Kit, Trick Flow Heads and Custom Cam - 12psi - 714rwhp and 820rwtq / 100hp Nitrous Shot starting at 3000 rpms - 948rwhp and 1044rwtq still on 93
    2011 Vette Cam Only Internal Mod in stock LS3 -- YSI @ 18psi - 811rwhp on 93 / 926rwhp on E60 & 1008rwhp with a 50 shot of nitrous all through a 6L80

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  6. #6
    Early on I played with enrichment rate. Didn't make a difference.
    It is acting exactly like a VE maximum limiter like I've hit on the E40 ECUs. That too will only come about when running blended airmass.

  7. #7
    Senior Tuner 10_SS's Avatar
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    not much help here, but i also have ve and maf dialed in on my camaro e38... and also had similar weird problems when i tried Dynamic... so i went back to pure MAF. Doesnt make sense to me.
    2010 Camaro LS3 (E38 ECU - Spark only). MS3X running complete RTT fuel control (wideband).
    Whipple 2.9L, 3.875" Pulley, kit injectors, supplied MSD Boost-A-Pump, stock pump
    LG Motorsports 1 7/8" Headers - No Cats, stock mid pipe with JBA Axle Back
    ZL1 Wheels/Tires

  8. #8
    Solved! Dave Steck pointed out that Predictive Coefficients need to be zero'd. That took care of it all!

  9. #9
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    Quote Originally Posted by Proxses View Post
    Solved! Dave Steck pointed out that Predictive Coefficients need to be zero'd. That took care of it all!
    Just base or all of them? Honestly haven't run into this yet. Guess we learn something everyday.
    2010 Vette Stock Bottom LS3 - LS2 APS Twin Turbo Kit, Trick Flow Heads and Custom Cam - 12psi - 714rwhp and 820rwtq / 100hp Nitrous Shot starting at 3000 rpms - 948rwhp and 1044rwtq still on 93
    2011 Vette Cam Only Internal Mod in stock LS3 -- YSI @ 18psi - 811rwhp on 93 / 926rwhp on E60 & 1008rwhp with a 50 shot of nitrous all through a 6L80

    ~Greg Huggins~
    Remote Tuning Available at gh[email protected]
    Mobile Tuning Available for North Georgia and WNC

  10. #10
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    I use the HPT custom op system. Never seen this occur.
    When arguing with an idiot, make sure he isn't doing the same thing....

  11. #11
    Quote Originally Posted by Proxses View Post
    Solved! Dave Steck pointed out that Predictive Coefficients need to be zero'd. That took care of it all!
    I saw a similar issue on mine which is blown. It only happened once before I corrected, but it started running lean at 130+ kPa MAP. Scary. Glad i did no damage.

    I zero'd all Predictive Coefficients to fix.

    Sorry I didn't post earlier. I did not make a connection until after you posted this. Glad Dave was able to point you in the right direction.

    I am still very curious about these tables...

    http://www.hptuners.com/forum/showth...n-Coefficients

  12. #12
    Senior Tuner 10_SS's Avatar
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    I also use the custom 2bar and had the same problem.. will be trying this out. 99% of my settings were the same as the OP..
    2010 Camaro LS3 (E38 ECU - Spark only). MS3X running complete RTT fuel control (wideband).
    Whipple 2.9L, 3.875" Pulley, kit injectors, supplied MSD Boost-A-Pump, stock pump
    LG Motorsports 1 7/8" Headers - No Cats, stock mid pipe with JBA Axle Back
    ZL1 Wheels/Tires

  13. #13
    makes sense that these would be zero'ed once you have your MAF and VE dialed in. But one would think this was a more common talked about item. I have been dealing with a lean condition at start up, wonder if these predicted coefficients can be causing that. So if you zero all of these do you need to tune your VE again?
    Last edited by edge04; 09-01-2015 at 05:53 PM.

  14. #14
    Quote Originally Posted by edge04 View Post
    makes sense that these would be zero'ed once you have your MAF and VE dialed in. But one would think this was a more common talked about item. I have been dealing with a lean condition at start up, wonder if these predicted coefficients can be causing that. So if you zero all of these do you need to tune your VE again?
    As far as I can tell from descriptions and how powerful and advanced these computers are, these tables are using previous and current values for throttle, MAP, etc to predict the next value.

    You can imagine if the last throttle position was 50%, current is 60% and the last MAP value was 70kPa and current is 90kPA, then the next values for both will be higher. I am just spitballing here, but its a predictive logic of types.

    Also based on these, I imagine there is some kind of Alpha-N calibration, values, estimates, etc in these computers. Not sure it is just very basic or if HP Tuners has chosen to ignore mapping these items, but its seems like throttle position may play a bigger role in airflow estimation than we all imagine (at least when enabled).

  15. #15
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    Quote Originally Posted by 10_SS View Post
    I also use the custom 2bar and had the same problem.. will be trying this out. 99% of my settings were the same as the OP..
    Interesting.... So do you think this would only apply to boosted applications, or N/A as well?? Could these be somewhat of a transient fuel multiplier?
    When arguing with an idiot, make sure he isn't doing the same thing....

  16. #16
    Senior Tuner 10_SS's Avatar
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    I tested it... 0'ing the tables also work for me. Makes sense since we got rid of the OE tables by switching to the 2bar with Standard VE table so the other settings such as these should also be de-activated. I didn't have a problem below 95kpa (non boost)... just the PE region. So the problem is likely still there with N/A, just maybe not as noticeable?
    2010 Camaro LS3 (E38 ECU - Spark only). MS3X running complete RTT fuel control (wideband).
    Whipple 2.9L, 3.875" Pulley, kit injectors, supplied MSD Boost-A-Pump, stock pump
    LG Motorsports 1 7/8" Headers - No Cats, stock mid pipe with JBA Axle Back
    ZL1 Wheels/Tires

  17. #17
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    I zeroed them out. I'm not real sure what to expect, as I have not had this lean problem the OP had. I'll monitor trims and general performance for a few days and see how it goes.
    When arguing with an idiot, make sure he isn't doing the same thing....

  18. #18
    Advanced Tuner ttz06vette's Avatar
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    You guys zeroing out all of the tables under the Predicted Coefficient menu?

  19. #19
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    Yes... Dynamic airflow tab.
    When arguing with an idiot, make sure he isn't doing the same thing....

  20. #20
    Advanced Tuner ttz06vette's Avatar
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    I'm game for giving it a shot. I have been battling an off idle lean condition by screwing with the transient fueling wall wetting tables. I run MAF only pretty much but it is clear that the transient tables effect things even in MAF mode. I'm going to reset all of these changes to stock and give this a try.