ty_ty13

iTrader: (42)

i've never seen any one do it nor do i know what to even search for...

but what is changed when tunning a MAF car that differs from a SD with no o2 feedback....

i hear about PE but im not sure where that is to tune either....


enlighten me a little im sure i'll understand it if i can tune my own stuff with SD im just concerned about doing other peoples cars that have/want there MAF.....

ty_ty13

iTrader: (42)

i saw the redhard supra has a VE translator excel sheet for the MAF but i cant seem to find it... any help on that?

ringram

use the same process that you alter ve to alter maf table.

(ie) If ve is accurate but the tune is out then its maf table fault so apply the relevant corrections to the maf table to make fueling accurate.

apply the corrections iteratively until error is acceptable, first to ve table in sd mode, then to maf table in hybrid factory maf mode.

ty_ty13

iTrader: (42)

so if i can dial in a VE table well, then tunning the MAF table(s) should be no problem?

Gary Z

In SD mode, Dynamic Airflow is an estimate of airflow that would be measured by the MAF. If you have a good SD tune then the estimate should be fairly accurate. If, with the MAF connected but still running in SD mode, you record Dynamic Airflow and MAF frequency, you will have the information needed to calibrate the MAF. One way to do this is to make an XY graph of Dynamic Airflow versus MAF frequency using Excel. If you then generate a polynomial fit to the data (using Excel's trendline feature), you can use the polynomial to generate a MAF calibration curve. I don't have my notes handy but my recollection is that I used two separate third-order polynomials - one for the low frequency end of the curve, and another for the high end.

2002_Z28_Six_Speed

iTrader: (19)

Very methodical. Good job.

Can one not just log the frequency vs the AFR and adjust the MAF table based on the trends at each frequency column?

I don't understand how you crossreference... Is the airflow based on the VE which you have previously calibrated??

Gary Z

Perhaps, but it seems to me that this would be equivalent to tuning by tweaking VE, or the IFR, or the PE table. I use the PCM as GM intended, closed-loop, with the MAF. The main appeal, for me, of SD mode is that removing the MAF eliminates an unknown and thereby creates a simpler system. I have calibrated (flow-tested Ford 30) injectors and assume my IFR table is accurate. That is my starting point. I have an apparently good SD tune so I think my VE table is reasonably accurate. My MAF calibration agrees with my SD tune as shown by the fact that my LTFTs change little whether or not the MAF is used. There are probably flaws in this method. I still have a lot to learn.

RedHardSupra

iTrader: (1)

GaryZ, you're dead on!
MAF is a 3rd order poly, that's a physical dependency, and as such you cannot dodge it. I do not agree with using AFR%error based adjustments to the stock curve as that ruins the shape of the polycurve.

the way it should be done we should use airflow estimates created from fuel and AFR measurements

airflow=cylinders*cylinder airmass*rpm/120
where
cylinderairmass= IPW*IFR*AFRwb

and then chart it against MAFhz, and fit the 3rd order poly to this function, hopefully also removing the obvious outliers. this method is highly dependent on how realistic your IFR figures are, and how well your wideband is calibrated, that's good data cleanup and robust fitting techniques are highly recommended.

2002_Z28_Six_Speed

iTrader: (19)

That explains how you could crossreference reality. Thank you. This helps alot.