MAF calibration?

[leres]

Ok, so I've upgraded my 2000 SS Camaro to a stock 2002 OS and then spent some time tweaking the main VE table as per the fine AutoVE tuning document. Running with the stock 2000 OS/calibration, I was seeing LTFTs of 3-4 in the higher RPM and MAP cells. With the 2002 OS and a tweaked VE table, I'm now seeing LTFTs in the 4-5 range. It seems like calibrating the MAF is my next step.

I started by using the technique described here:

http://www.efilive.com/forum/viewtop...?p=13008#12957

I used a normal calibration but with STFT and LTFTs disabled and logged BEN from my PLX. But it's hard to get a lot of data with a 5 minute test drive but it looks like my stock MAF calibration is fairly off so I decided to start by doing some kind of uniform increase. I wrote an excel spreadsheet that gives me a range of factors from N to M that is sloped the same as my stock MAF. For example, if I wanted to raise 1500 Hz by 1% and 12000 Hz by 5%, it gives me a series of numbers that go from 1.01 to 1.05; if you graph these they have the same shape as the stock MAF calibration. I haven't tried a normal calibration to see what the LTFTs will do yet but after a couple iterations, it's clear I'm going in the right direction. I've been making small changes to the low frequencies and they don't seem to be changing (I keep coming up with number around 1.01). The higher frequencies have dropped from 1.05 or 1.06 down to 1.03 but I've raised them more than 10% so it doesn't loop to me as if the BEN factor works as well here as it does with the VE table (in the case of updating VE cells, as soon as I got 50 or more data points to make an update to a cell, it would stay within a few percent for later rounds of VE tuning).

I ran across this interesting page:

http://www.allmod.net/hpt/

In the comments for the spreadsheet, he suggests putting the car in SD mode (according to the AutoVE tuning doc I guess this means just setting {C2901} "MAF High Frequency Fail 1" to zero) and then to log "Dynamic airflow" and "MAF Hz" Logging (calculated) airflow seems like a better idea since you don't have to worry about the fuel trims. His spreadsheet also does some fancy tricks to average values in boxes around multiple points.

Anyway, I'm hoping that at least a couple of experienced dudes still use their MAFs and could help get me on the right track.

[SSpdDmon]

Try using STFT's to adjust your low end maf frequencies. It really helped me dial in mine. Once you get close, only ajdust by half of the average % correction. It sounds like you're comfortable with using Excel. So, you could either create your own tool or you could use mine if you'd like.

With mine, I logged STFT % vs. MAF freq. vs. RPM. Set the RPM up in the column with one label (?,8000). Then, set the rows up to replicate the MAF chart and the cells to show the average STFT % correction. After you log, you just set a target LTFT %, set a minimum cell count (to exclude cells with little activity), paste in your stock maf table, current maf table, cell counts (N), and your STFT %'s (x). Give it a try...

[leres]

I assume you want to disable LTFT updates but leave everything else stock?

[SSpdDmon]

Yes. Get withing +/-10 with your LTFT's and then turn them off.