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Thread: MAF Smoothing Tool for most Gen IVs

  1. #1
    Senior Tuner DSteck's Avatar
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    MAF Smoothing and VE Builder Tool for most Gen IVs

    I got a little bored today (lazy Sunday), and decided to throw together an Excel sheet. This method is something I use to help smooth out MAF curves after roughing them in. Sometimes certain areas don't have enough data, or the curve just looks like hell anyway, or a host of other reasons... Anyway, it is pretty straight forward. Paste the existing MAF table and it gives you a new one. There's three formats right now. One tab is for cars with two MAF tables, another tab is for cars that have two MAF tables but run the enhanced OS that extends the range, and the last is for most of the new Gen IV stuff in the E38/E67 PCMs.

    What this does is take your existing curve and fit a 3rd order polynomial to it, forcing an intercept at zero (basicaly assuming that at 0Hz, the airflow is 0 lb/min). It then takes the refit and applies it to the axis labels to give you a new "pretty" curve. Please note... this is NOT meant to fix issues you have and is not intended to make your MAF curve perfect. In an ideal world, the MAF would perfectly follow a 3rd order polynomial. Things like injector data that's off, turbulence, or whatever can cause it to deviate. This is just intended to help you keep the MAF curve at a reasonable shape.

    I've found that when I use this, it helps fill in that middle ground area of the MAF where you aren't at WOT and aren't in normal drivability. After applying it, generally you need to go back and check it, and adjust as neccessary. This can throw your low frequencies a little far out, but the numbers around WOT are typically valid. You can re-use this after every time you apply error if you want, or just use it once to smooth things out and fine tune from there. That is up to you.

    NOTE: On the operating systems that are clamped at 67.7 lb/min of airflow (or 130-something for the custom OS in early E38 stuff), the spread sheet will automatically ignore cells that are maxed out (67.7 or 135.4) in the calculation. Also, if you want it to ignore certain cells, just enter 0 in the MAF table for that frequency and it will not use it. This is handy if you want to ignore the frequencies below idle.

    Let me know what you think!

    Updated to include carlrx7's request to show the percentage change. Green means it went lower, red means it went higher. Also updated to ignore cells entered as zero or cells that use the max value for that application.

    Also updated to include VE builder.

    In both spread sheets, entering a value of zero will cause that cell to be ignored. The VE Builder file needs to be renamed .xls before opening it.
    Last edited by DSteck; 12-23-2011 at 09:36 AM.

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  2. #2
    Tuner Mez's Avatar
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    Quote Originally Posted by DSteck View Post
    I got a little bored today (lazy Sunday), and decided to throw together an Excel sheet. This method is something I use to help smooth out MAF curves after roughing them in. Sometimes certain areas don't have enough data, or the curve just looks like hell anyway, or a host of other reasons... Anyway, it is pretty straight forward. Paste the existing MAF table and it gives you a new one. There's three formats right now. One tab is for cars with two MAF tables, another tab is for cars that have two MAF tables but run the enhanced OS that extends the range, and the last is for most of the new Gen IV stuff in the E38/E67 PCMs.

    What this does is take your existing curve and fit a 3rd order polynomial to it, forcing an intercept at zero (basicaly assuming that at 0Hz, the airflow is 0 lb/min). It then takes the refit and applies it to the axis labels to give you a new "pretty" curve. Please note... this is NOT meant to fix issues you have and is not intended to make your MAF curve perfect. In an ideal world, the MAF would perfectly follow a 3rd order polynomial. Things like injector data that's off, turbulence, or whatever can cause it to deviate. This is just intended to help you keep the MAF curve at a reasonable shape.

    I've found that when I use this, it helps fill in that middle ground area of the MAF where you aren't at WOT and aren't in normal drivability. After applying it, generally you need to go back and check it, and adjust as neccessary. This can throw your low frequencies a little far out, but the numbers around WOT are typically valid. You can re-use this after every time you apply error if you want, or just use it once to smooth things out and fine tune from there. That is up to you.

    NOTE: On the operating systems that are clamped at 67.7 lb/min of airflow (or 130-something for the custom OS in early E38 stuff), you will have to input some fake values at the end of the MAF curve so that the tail end isn't just flat at the limit. There is an example in each sheet to help you understand. Basically just plug in some values at the end to make it look like it follows the trend.

    Let me know what you think!
    Thanks.

    I did my own but it was ugly and not as mathematically sound as you have done.
    Last edited by Mez; 12-18-2011 at 04:26 PM.
    2014 Corvette, Z51, 3LT, 7-Speed, NPP, 2 tops, Exposed Carbon Fiber roof, FAY, Laguna Blue, Kalahari, Museum Delivery.

  3. #3
    Tuner 07MontRedcp's Avatar
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    Thanks, this will come in very handy when I convert my stock APS TT tune to the custom 2 bar and replace the stock maf with an ABACO 3.5" maf that is rated for 1024 grams/sec.

    BJK
    Last edited by 07MontRedcp; 12-19-2011 at 02:12 AM.
    APS TT 630 rwhp/654 rwtq @ 9 psi
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    i was just going to hit you up again, thanks dave!

  5. #5
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    p.s. how hard would it be to add another table to display % of change under which cell.

  6. #6
    Senior Tuner DSteck's Avatar
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    I can add that pretty easy. I'll have to play with cell spacing a bit. I wanted everything to try and stay on the screen at the same time for the most part.

    07MontRedcp, why wouldn't you just do an LS7 MAF?

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    Doesn't work with OpenOffice...works great in Excel though. Thank you.

  8. #8
    Tuner 07MontRedcp's Avatar
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    Quote Originally Posted by DSteck View Post
    I can add that pretty easy. I'll have to play with cell spacing a bit. I wanted everything to try and stay on the screen at the same time for the most part.

    07MontRedcp, why wouldn't you just do an LS7 MAF?


    Because I was intrigued by the electronics, i.e the programable ranges (up to 10 that are selectable), two thin sensor boards at right angles, and the fact that it's max flow is rated at 1,027 grams (the 3.5" model, which btw, fits perfectly into my intake plumbing) making it a perfect fit for the custom os tables.

    BJK
    Last edited by 07MontRedcp; 12-18-2011 at 06:26 PM.
    APS TT 630 rwhp/654 rwtq @ 9 psi
    '07 C6, TR6060 conversion w/Z06 ratios. DTE Stage 4 Quaife Diff w/brace (3.73). Z06 Brakes, mild turbo cam & dual springs (222/222, LSA 115, .581/.581), LS9R clutch, LG GT2 Coilovers, Autometer Cobalt Fuel gauage, Progressive Alky Controller, and e-Boost2 Controller. PFADT poly bushing for control arms and Sports sway bars. MGW shifter. 3" B&B Fusion. RSI Stage 1.5 fuel system. RX dual valve catch can.

  9. #9
    Senior Tuner DSteck's Avatar
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    The LS7 MAF with the custom OS is good to the same and is probably a lot cheaper. My TT Z06 runs MAF only just great.



    If there are other MAF table formats people want, let me know.

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  10. #10
    Tuner 07MontRedcp's Avatar
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    It's because of your posts about "maf only" that I have decided to do the same. at least until I can get to a load bearing dyno.

    BTW, I will have two frequency choices for the ABACO output (I bought it several years ago) 12.4 kHz and 15.5 kHz. I would like to go with the 15.5, but I'm not sure if the '07 e38 will balk on the higher frequency when using the custom os.

    BJK
    Last edited by 07MontRedcp; 12-19-2011 at 02:19 AM.
    APS TT 630 rwhp/654 rwtq @ 9 psi
    '07 C6, TR6060 conversion w/Z06 ratios. DTE Stage 4 Quaife Diff w/brace (3.73). Z06 Brakes, mild turbo cam & dual springs (222/222, LSA 115, .581/.581), LS9R clutch, LG GT2 Coilovers, Autometer Cobalt Fuel gauage, Progressive Alky Controller, and e-Boost2 Controller. PFADT poly bushing for control arms and Sports sway bars. MGW shifter. 3" B&B Fusion. RSI Stage 1.5 fuel system. RX dual valve catch can.

  11. #11
    Senior Tuner DSteck's Avatar
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    Just for sake of comparison, with my stock MAF in the TTi tube, I made about 800whp at 12,900Hz.



    Spreadsheet was updated to ignore cells with a zero value, or with a max value for that application.
    Last edited by DSteck; 12-18-2011 at 08:59 PM.

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  12. #12
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    So how do I unlock this spreadsheet so I can look at the formulas?

  13. #13
    Senior Tuner DSteck's Avatar
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    Find me a sweet grass basket that isn't horribly overpriced. Lol.

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  14. #14
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    I have no clue how people expect to do science without simple bug hunting, yet alone peer review proper. Besides, I produced a spreadsheet that did just about the same thing back in February of 2005 so this is more of a trip down memory lane than bringing up new stuff... Unless you're hiding how to do robust fitting in Excel, in which case I'm both interested and impressed

  15. #15
    Senior Tuner DSteck's Avatar
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    That's what I'm hiding (calculating the coefficients). Any Joe Schmoe can fit a trendline to a graph and copy/paste the coefficients. This automates the whole process. I don't stand to make money off this, and it isn't really difficult to do... But I at least want something to call my own. Lol.

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  16. #16
    Advanced Tuner ttz06vette's Avatar
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    Quote Originally Posted by 07MontRedcp View Post
    It's because of your posts about "maf only" that I have decided to do the same. at least until I can get to a load bearing dyno.

    BTW, I will have to two frequency choices for the ABACO output (I bought it several years ago) 12.4 kHz and 15.5 kHz. I would like to go with the 15.5, but I'm not sure if the '07 e38 will balk on the higher frequency when using the custom os.

    BJK
    Let me know how it goes with the abaco if you try the 15.5. I have had good luck with this MAF in general. I needed it to smooth out my signal due to my intercooler design causing turbulence in my MAF. By setting the "noise threshold" setting to 1 under the advanced settings, it smoothed out my signal perfectly. In effect it is allowing these fluctuations from the intercooler design to bypass the averaging process the MAF goes through which was causing a lean tip in with my stock MAF.

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    Quote Originally Posted by DSteck View Post
    Find me a sweet grass basket that isn't horribly overpriced. Lol.

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    hmmm



    seeing that my car idles at 2000-2200 hz, and the new maf has a 69% increase in value, i think i might have an issue. lol

  19. #19
    Tuner 07MontRedcp's Avatar
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    Quote Originally Posted by ttz06vette View Post
    Let me know how it goes with the abaco if you try the 15.5. I have had good luck with this MAF in general. I needed it to smooth out my signal due to my intercooler design causing turbulence in my MAF. By setting the "noise threshold" setting to 1 under the advanced settings, it smoothed out my signal perfectly. In effect it is allowing these fluctuations from the intercooler design to bypass the averaging process the MAF goes through which was causing a lean tip in with my stock MAF.
    Will do, but it will probably be early spring before the car is back together enough to start messing with the new maf. Right now I am just starting to get the upgraded drive train, fuel system, and duel radiator fans reinstalled along with getting a turbo out for oil seals.

    BJK
    Last edited by 07MontRedcp; 12-19-2011 at 12:37 PM.
    APS TT 630 rwhp/654 rwtq @ 9 psi
    '07 C6, TR6060 conversion w/Z06 ratios. DTE Stage 4 Quaife Diff w/brace (3.73). Z06 Brakes, mild turbo cam & dual springs (222/222, LSA 115, .581/.581), LS9R clutch, LG GT2 Coilovers, Autometer Cobalt Fuel gauage, Progressive Alky Controller, and e-Boost2 Controller. PFADT poly bushing for control arms and Sports sway bars. MGW shifter. 3" B&B Fusion. RSI Stage 1.5 fuel system. RX dual valve catch can.

  20. #20
    Senior Tuner DSteck's Avatar
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    The lower range typically gets changed quite a bit. You can pick and choose which section of the new curve you want. The lower the number, typically the greater the error will be after fitting just because of resolution. Copy the new stuff from about 4600 on up. The low load area is also subject to turbulence which makes the MAF calibration want to be even farther from ideal.

    You can also do it again and zero everything below idle and above 4600. It'll then only use that specific range to calculate a new curve. Then just copy the same range from the new table.

    It's not meant as a magic fix or anything. The biggest benefit I've had is just filling in the mid section of the MAF where it's a little more difficult to get a steady stream of data.

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