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Old 07-05-2011, 08:03 PM   #11
JR-Vette
 
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Drives: 1999 500 HP Corvette
Join Date: Jan 2010
Location: West Coast
Posts: 164
That tip is not valid for most NA powertrains as no performance gains would come of using a higher MAF output to a PCM that only can compare to the lower max freq value in MAF table of PCM

If the MAF frequency tables in the PCM is looked at you find most GM newer cars like Camaro have a maximum value of 12,200 Hz ( NA engines) or 15,000 Hz for like boost, IE, new ZR1

If you look at a 2010 ZR1 at a drag strip recorded scanner data even at high boost the maximum MAF (air mass ) moved is about 9900 Hz.
No where near the maximum ability of the MAF output or MAF PCM table
In this case max airmass was about 75 lbs and about 1.4 grms/cyl

Stock 2010 ZR1 at drag strip in 90 degree weather

Code:
MAFLb   MPH   MAP   BoostPSI   MAFRQ   MAFgrms   grmcyc   MapKpa       75   65   51   11   9720   569   1.389   173       75   65   51   11   9720   569   1.263   173       75   65   51   11   9720   569   1.263   173       75   65   51   11   9888   569   1.263   173       75   65   51   11   9888   569   1.263   173       70   88   47   9   9673   531   1.358   160       70   88   47   9   9673   531   1.281   160       70   88   47   9   9673   531   1.281   160       70   88   47   9   9768   531   1.281   160       70   88   47   9   9768   531   1.281   160       74   89   48   10   9673   558   1.392   162       74   89   48   10   9673   558   1.309   162       74   89   48   10   9673   558   1.309   162       74   89   48   10   9925   558   1.309   162       74   89   48   10   9925   558   1.309   162       74   92   48   10   9768   560   1.350   163       74   92   48   10   9768   560   1.257   163       74   92   48   10   9768   560   1.257   163       74   92   48   10   5298   560   1.257   163       74   92   48   10   5298   560   1.257   163       70   115   47   9   9626   531   1.343   160       70   115   47   9   9626   531   1.296   160       70   115   47   9   9626   531   1.296   160       70   115   47   9   9673   531   1.296   160       70   115   47   9   9673   531   1.296   160       71   117   48   10   9673   539   1.323   164       71   117   48   10   9673   539   1.294   164       71   117   48   10   9673   539   1.294   164       71   117   48   10   9720   539   1.294   164       71   117   48   10   9720   539   1.294   164       73   119   48   9   9673   550   1.341   161       73   119   48   9   9673   550   1.295   161       73   119   48   9   9673   550   1.295   161       73   119   48   9   9828   550   1.295   161       73   119   48   9   9828   550   1.295   161       71   121   49   10   9720   539   1.294   165       71   121   49   10   9720   539   1.262   165       71   121   49   10   9720   539   1.262   165       71   121   49   10   9876   539   1.262   165       71   121   49   10   9876   539   1.262   165       74   124   49   10   9876   560   1.310   166       74   124   49   10   9876   560   1.273   166       74   124   49   10   9876   560   1.273   166       74   124   49   10   9937   560   1.273   166       74   124   49   10   9937   560   1.273   166
If we compare that with the recorded scanner data of a 2010 LS3 Camaro
maximum MAF output is about 8,700 Hz ( no where near the 12,000 HZ MAF limit) and less then 50 lbs airmass peak

In neither case did 400 HP or 640 HP was limited by MAF and that is clear because you would rarely see anyone post having a DTC error of HIGH MAF value hit.

2010 LS3 Camaro
Code:
MAF   MPH   MAFRQ   MAFgrms   grmcyc       47   75   8686   355   0.834       47   75   8686   355   0.781       47   75   8686   355   0.781       47   75   8247   355   0.781       47   75   8247   355   0.781       47   75   8247   355   0.781       47   74   8492   355   0.840       47   74   8492   355   0.786       47   74   8492   355   0.786       47   74   8438   355   0.786       47   74   8438   355   0.786       47   106   8492   355   0.816       47   106   8492   355   0.795       47   106   8492   355   0.795       47   106   8583   355   0.795       47   106   8583   355   0.795       46   57   3511   351   0.780       46   57   3511   351   0.923       46   57   3511   351   0.923       46   57   8230   351   0.923       46   57   8230   351   0.923       46   91   8602   351   0.963       46   91   8602   351   0.919       46   91   8602   351   0.919       46   91   8385   351   0.919       46   91   8385   351   0.919       46   70   8501   350   0.882       46   70   8501   350   0.821       46   70   8501   350   0.821       46   70   8686   350   0.821       46   70   8686   350   0.821       46   70   8359   350   0.950       46   70   8359   350   0.827       46   70   8359   350   0.827       46   70   8492   350   0.827       46   70   8492   350   0.827       46   94   8385   350   0.916       46   94   8385   350   0.880       46   94   8385   350   0.880       46   94   8547   350   0.880       46   94   8547   350   0.880       46   94   8547   350   0.880       46   100   8547   350   0.880       46   100   8547   350   0.831       46   100   8547   350   0.831       46   100   8359   350   0.831       46   100   8359   350   0.831       46   104   8359   344   0.818       46   104   8359   344   0.791       46   104   8359   344   0.791       46   104   8492   344   0.791       46   104   8492   344   0.791       45   90   8528   340   0.943       45   90   8528   340   0.903       45   90   8528   340   0.903       45   90   8565   340   0.903       45   90   8565   340   0.903       45   48   8429   339   0.920       45   48   8429   339   0.801       45   48   8429   339   0.801       45   48   8447   339   0.801       45   48   8447   339   0.801       45   65   8510   339   0.872       45   65   8510   339   0.855       45   65   8510   339   0.855       45   65   8501   339   0.855
Since cars today have 20 or more electronic controllers, under sized unshielded wire and other functions can produce/output EMI and RFI so clipping the signal reduces chances of MAF output being effected by the above and also the PCM hardware quad drivers.

As the elevation increases the airmass decreases and the same cars above that were at sealevel would require or use less airmass and see lower MAP.

Being NA engines will never reach 12,200 Hz there would be zero reason or gain changing MAF and in fact the new MAF output would not match the MAF table such as if maximum MAF frequency your PCM is 12,000 Hz and the new MAF outputs 15,000 Hz the PCM would not understand any values above the 12,000 Hz and would require a PCM code segment from another PCM that did support 15,000 Hz
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