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Thread: Stock truck with VVE off by more then 10%????

  1. #1
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    Stock truck with VVE off by more then 10%????

    I have a 2014 Silverado with a 5.3 Bone stock. In the tune all that has been done is disable DOD, trans tune using the bluecat tool and slight changes to driver demand table. After lot of reading and learning ive set up several graphs to try and log VVE error in the scanner. The graphs "VVE CL", "VVE w LTFT" and "VVE w STFT only" are set up with math from Cringer. The 4th graph, "GMVE STFT % error", is setup using SmokeShows math for dual MAF and VVE tuning. I have made sure each channel needed for the MATHS is logged and set up with the correct units and all 4 have a filter for transients i allso got from cringer.

    If you view the screen shot/ logs you will see that Im getting what seems to me a pretty large error in the graphs for a bone stock truck. So here is my question... dos that look normal for VVE to be that far off on a stock truck? If i take the VE airflow reading and multiply it by the Error value in the graph it dos get it pretty close to Dynamic airflow reading (most of the time its a little high).

    NOTE: Im not sure if the math will load when you open the log file. At first im just going to upload the two logs and tune file if the maths expressions are needed let me know. And if anyone is wondering why im doing this on a stock truck im just trying to get a grasp on how to do it. Thanks for any insight.
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  2. #2
    Advanced Tuner 04silverado6.0's Avatar
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    Disable ltft and dfco. Get a log and see how it looks.

  3. #3
    Tuner CYN_CRVR's Avatar
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    I personally would leave LTFT enabled, but then you should only be looking at error formulas that include both LTFT + STFT in the calculations. You should ignore any STFT-only formulas.

    ...unless you disable LTFT as the previous post suggested, then do the opposite of this.

  4. #4
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    Perhaps its the way you are calculating it.

    I'm not a fan of using the MAF to dial in VVE. Try disabling the MAF entirely and see how VVE stands by itself.
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    Thanks for the replies. i will disable DFCO and try both ways to see what i get. Is there anything els i should disable in the tune? I saw Huggins mention in a post changing the VE base temp to the current ambient temp while tuneing.

  6. #6
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    That's the only way I've found for the VE to stay right with changing temps otherwise you can dial it in - and it doesn't matter the method used - at one temp and the next time you check it, it would be off up to 20% depending on the ambient temp at that time. Sure shift still occurs, but ever since I started having customers do that the VE errors have stayed really tight. I just really wish there was a way to adjust the VE better for changing temps.
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    Awesome thanks for the reply i will add that to my notes to make sure i do. I have another question for yall dos the VVT need to be zeroed out while logging and making changes to VVE?

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    My V was like 16% off on both banks, bone stock. No toon, no nothing. Just saying. Lol

  9. #9
    Tuner CYN_CRVR's Avatar
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    Quote Originally Posted by Williamblake View Post
    Awesome thanks for the reply i will add that to my notes to make sure i do. I have another question for yall dos the VVT need to be zeroed out while logging and making changes to VVE?
    I don't have even 1/10 the experience of some of the other folks in this thread, but IMO the simplest process for you with a stock car will be this:
    1) [optional] if you want to adjust your VVT behavior, edit those tables first
    2) leave VVT enabled while logging
    3) only make changes to the base VVE table to reduce your errors (don't bother with the other valve angle-dependent tables)

    This should enable you to minimize your VE errors in the fewest number of steps.

  10. #10
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    Quote Originally Posted by Williamblake View Post
    Thanks for the replies. i will disable DFCO and try both ways to see what i get. Is there anything els i should disable in the tune? I saw Huggins mention in a post changing the VE base temp to the current ambient temp while tuneing.
    I do not do this and do not have a problem with them coming out consistent.
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  11. #11
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    Quote Originally Posted by Alvin View Post
    I do not do this and do not have a problem with them coming out consistent.
    Same...

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    Awesome. I think i have a good game plane now. I appreciate all of yalls input.

  13. #13
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    Alright i set the tune up with DFCO off COT off VE base temp set to ambient, 82 degrees. MAF still running normally.

    In the screen shot on the left is smoke shows math altered to use LTFT and STFT : GMVE STFT % error = ((MAF_af)*(1+(STFT_avg+LTFT_avg)/100)-(GMVE_af))/(GMVE_af)*100

    And on the right is Cringers dynamic air math : ((DynAir+(DynAir*(STFT + LTFT)/100))-VVE)/VVE*100

    Both a running the same transients filtering. I though it was a pretty interesting comparison so i figured id post it up.
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  14. #14
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    Quote Originally Posted by Williamblake View Post
    Alright i set the tune up with DFCO off COT off VE base temp set to ambient, 82 degrees. MAF still running normally.

    In the screen shot on the left is smoke shows math altered to use LTFT and STFT : GMVE STFT % error = ((MAF_af)*(1+(STFT_avg+LTFT_avg)/100)-(GMVE_af))/(GMVE_af)*100

    And on the right is Cringers dynamic air math : ((DynAir+(DynAir*(STFT + LTFT)/100))-VVE)/VVE*100

    Both a running the same transients filtering. I though it was a pretty interesting comparison so i figured id post it up.
    So long as you maintain steady state in each, they ought to be virtually indistinguishable. When everything is smooth, dynamic airflow=MAF.

  15. #15
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    i did notice after posting that i was logging regular LTFT and STFT but not the averages so maybe that is where the difference comes from?