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View Full Version : HOW TO: scale your MAF [pics]



fusionchicken
03-05-2007, 05:49 PM
Credit goes to l2r99gst for fingering this out. I really don't know a ton about this, so hopefully other people can chime in for questions.


This is a step-by-step of how to change the scaling for your MAF.
This doesn't affect your map. It affects the way ecuflash reads your map and how you interpret it. Once you change this, it will apply to all maps that you load with ecuflash.


Step 1: Load up ecuflash and right click on MAF scaling. Select "edit map"
http://www.sscustom.net/evo/tutorials/mafscaling/step1.jpg

Step 2: Here is what the finished table should look like. Circled in red are the important things. Click on the "Scalings..." button to add your custom scale.
http://www.sscustom.net/evo/tutorials/mafscaling/step2.jpg

Step 3: Click on the "add" button to create a new custom scale
http://www.sscustom.net/evo/tutorials/mafscaling/step3.jpg

Step 4: Here is a pic of what comes up. This is the screen that you will edit to make your new scale.
http://www.sscustom.net/evo/tutorials/mafscaling/step4.jpg

Step 5: Enter in the values that I've circled in red. Click "ok"
http://www.sscustom.net/evo/tutorials/mafscaling/step5.jpg

Step 6: Now you're back at the "edit table" screen. Make sure that the Y axis load scaling points to the scale that you just created. Use the dropdown menu to select it.
http://www.sscustom.net/evo/tutorials/mafscaling/step6.jpg

Finished: Your old scale and your new scale. Old one begins with 192. New one begins with 19.
http://www.sscustom.net/evo/tutorials/mafscaling/step7a.jpghttp://www.sscustom.net/evo/tutorials/mafscaling/step7b.jpg



Here is an example of how you actually put it into action.

Step 1: First you need to datalog your short term and long term fuel trims at a given MAF reading. This tells you how far "off" you are. So if your trims are +10%, that means you need to scale the MAF by 10%. The reading can be in Hz, lb/min, L/min, L/sec etc. Ultimately we want to end up reading MAF in Hz because that is what we just scaled ecuflash to. I've included a chart which can get you a rough idea of how to convert to Hz.

Here is a shot of what I logged with my OBDII scanner.Â* Notice the long term fuel trim, short term fuel trim, and I have my choice of reading my MAF in lb/min or g/s. My OBDII scanner gives both these values. Yours might give a different one.
http://www.sscustom.net/evo/tutorials/mafscaling/example1.jpg

Here is a nice chart provided by l2r99gst that will help you convert whatever unit you are reading MAF to Hz used by ecuflash. For the example, you can see that with my OBDII log above, that I will use either lb/min or g/s to find the corresponding Hz value that ecuflash uses.
http://www.sscustom.net/evo/tutorials/mafscaling/example2.jpg



So...here is how you find out just how "off" you really are.
You add your long term trim and your short term trim together for any given MAF value. Here you see 12.5 + 10.9 when my MAF reads 0.327lb/min
http://www.sscustom.net/evo/tutorials/mafscaling/example3.JPG



I need to find out where my 0.327lb/min falls on the ecuflash map so I look at this chart. I find my lb/min value. It's very close to the one given on the chart. I look over to my right to see what value ecuflash has associated with that row. It's 18.75 (actually 19 because ecuflash rounded up)
Another example: If I were datalogging and found my MAF value to be 4.00 lb/min I would look at this chart and know that I would need to adjust the 200 Hz value in ecuflash.
http://www.sscustom.net/evo/tutorials/mafscaling/example4.JPG





So now that I know i'm working with the 19 cell...here is how I actually calculate the changes that I need to make in order to scale.

My long term trim + my short term trim = 23%.
I need to add 23% to my MAF scale.
At the 19 cell, the factory value is 145.
There is an 'adder' value that is used so always add 140 to the factory value.
145+ 140 = 285.
I want to add 23% of 285.
285 * 0.23 = 65.55
145(my original value) + 65.55 = 210.55
210.55 is my new value.
http://www.sscustom.net/evo/tutorials/mafscaling/example5.JPG

Here it is changed in the MAF scaling map.
http://www.sscustom.net/evo/tutorials/mafscaling/example6.jpg

Here is how I convert my lb/min to Hz.
I created a table in excel and did a "lookup" on that table.
http://www.sscustom.net/evo/tutorials/mafscaling/conversion.jpg

from: http://www.evolutionm.net/forums/showthread.php?t=249388