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Old 11-12-2019, 12:20 PM   #1
kareston
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Question MAF scaling on WRX 2.5

Hey guys. I have some question regarding MAF scaling, in logger I noticed that ecu reads MAF voltage up to 4.8v, but table in ROM ends at 4.69v and ECU reads air only to 4.69v. What should I do? Rescale MAF in open loop? Or is there some kind of way to transfer MAF scaling table from STI to WRX, as I saw STI MAF scaling goes up to 4.96v.
Car and specs: Impreza WRX Wagon, EJ255 with VF35 turbo, Mishimoto performance intake and front mount i/c
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Old 11-12-2019, 01:57 PM   #2
Bansheeboy11
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You can rescale your voltage values, the ECU does linear interpolation so it will continue to use the last cell's values based on the scaling you enter. You may lose resolution at a lower voltage/flow range but will have better value control at the higher numbers.
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Old 11-12-2019, 03:52 PM   #3
kareston
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Originally Posted by Bansheeboy11 View Post
You can rescale your voltage values, the ECU does linear interpolation so it will continue to use the last cell's values based on the scaling you enter. You may lose resolution at a lower voltage/flow range but will have better value control at the higher numbers.
As I understand, I can delete some of the lower values ie. second and fourth cell, move the rest and I'll have two open cells to extend voltage?
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Old 11-13-2019, 12:29 PM   #4
86Dreams
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Quote:
Originally Posted by kareston View Post
is there some kind of way to transfer MAF scaling table from STI to WRX, as I saw STI MAF scaling goes up to 4.96v.
yes you can copy the scaling from one rom to another. You may want to inspect them side by side in excel before hand.

if you are not reaching or exceeding the upper limits for MAFV with your set up then expanding the table is likely not necessary at this time.

Always make sure to use a wideband O2 sensor to calculate fueling error as the means for evaluating the need to change the maf scaling.
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Old 11-13-2019, 02:34 PM   #5
kareston
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yes you can copy the scaling from one rom to another. You may want to inspect them side by side in excel before hand.

if you are not reaching or exceeding the upper limits for MAFV with your set up then expanding the table is likely not necessary at this time.

Always make sure to use a wideband O2 sensor to calculate fueling error as the means for evaluating the need to change the maf scaling.
Yes, thats the problem. My MAF scaling table ends at 4,69 voltage=295,11 g/s. But during WOT MAFv goes up to 4,8v, so I guess that engine takes more air than ECU can see. I deleted few cell in scaling table lower part to make space in upper and copied scaling from the same model STI that goes up to 350 g/s. Tomorrow planned to go for a ride to see how it goes
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Old 11-14-2019, 08:42 AM   #6
kareston
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Yes, thats the problem. My MAF scaling table ends at 4,69 voltage=295,11 g/s. But during WOT MAFv goes up to 4,8v, so I guess that engine takes more air than ECU can see. I deleted few cell in scaling table lower part to make space in upper and copied scaling from the same model STI that goes up to 350 g/s. Tomorrow planned to go for a ride to see how it goes
For those who are interested. Car runs good in lower rpm, durin WOT ecu now sees abt 330 g/s and gives fuel as it should, so misson completed)
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