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3.5" Maf Scaling Table??

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Old May 14, 2011, 05:40 PM
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3.5" Maf Scaling Table??
I’m hoping some one here can give me a hand or a jump start with the maf scaling tables. I’m going to use a 3.5” maf housing that measures exactly 86mm ID. I measured the stock maf housing and I got 65mm ID. The new maf housing is roughly 31% larger. But from the treads I’ve been reading I think 31% increase to the table will be too much.
Anyone that doesn’t mind sharing there maf scaling tables for a 3.5” maf please post them.
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Old May 15, 2011, 06:14 AM
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1) use stock MAF
2) get trims and WOT afr logged
3) swap to 3.5" MAF, start with 1.4 multiplier
4) log trims and WOT AFR adjust scaling and smooth until you trims and WOT AFR match in step 2.
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Old May 15, 2011, 01:51 PM
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It really is that simple, worst case you want to overshoot a bit so it is on the rich side, then work your way back down leaner again to tweak it.

For reference I went with a 1.35 multiplier (35%) and trims are pretty close to what I had. Select the entries you want to change and choose "Multiply Data" under the edit menu and enter in the multiplier you want to use. I like to go to the View menu and do a "view graph" to verify they changed properly, the curve should be pretty much the same as before.
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Old May 15, 2011, 04:33 PM
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I had a little trouble finding these too, just happen to have them open so I'll share

evo10base.xml
Code:
    <scaling name="MAFVoltScaling" units="units" toexpr="x*5/1024" frexpr="x*1024/5" format="%.3f" min="0" max="5" inc="1" storagetype="uint16" endian="big"/>

    <table name="MAF Compensation" category="Fuel" type="2D" scaling="AirFlow16">
        <table name="X" type="X Axis" elements="40" scaling="MAFVoltScaling"/>
    </table>

    <table name="MAF Compensation #2" category="Fuel" type="2D" level="1" scaling="AirFlow16">
        <table name="X" type="X Axis" elements="40" scaling="MAFVoltScaling"/>
    </table>

    <table name="MAF Compensation #3" category="Fuel" type="2D" level="1" scaling="AirFlow16">
        <table name="X" type="X Axis" elements="50" scaling="MAFVoltScaling"/>
    </table>
52680015.xml
Code:
    <table name="MAF Compensation" address="5753a">
        <table name="X" address="615ea"/>
    </table>

    <table name="MAF Compensation #2" address="5758a">
        <table name="X" address="6163a"/>
    </table>

    <table name="MAF Compensation #3" address="575da">
        <table name="X" address="6168a"/>
    </table>
I settled on 1.39*stock values after starting at 1.48 (extra safe).

I'd just start at 1.4* just like tephra said. If you do the math, it works out:

area of circle: pi*r*r
inner diameter(stock): 2.8" (r=1.4)
inner diameter(primo): 3.3" (r=1.65)

area (stock) = 1.4*1.4*3.14 = 6.15 sq inches
area (primo) = 1.65*1.65*3.14 = 8.55 sq inches

conversion ratio (primo/stock): 8.55/6.15= 1.39

It is amazing how nicely the car runs on a maf this huge!
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Old May 15, 2011, 07:31 PM
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thanks for the help guys will try this tomorrow after work. Will post results or if i hav e any questions.
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Old May 16, 2011, 08:12 AM
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Originally Posted by scheides
I had a little trouble finding these too, just happen to have them open so I'll share

evo10base.xml
Code:
    <scaling name="MAFVoltScaling" units="units" toexpr="x*5/1024" frexpr="x*1024/5" format="%.3f" min="0" max="5" inc="1" storagetype="uint16" endian="big"/>

    <table name="MAF Compensation" category="Fuel" type="2D" scaling="AirFlow16">
        <table name="X" type="X Axis" elements="40" scaling="MAFVoltScaling"/>
    </table>

    <table name="MAF Compensation #2" category="Fuel" type="2D" level="1" scaling="AirFlow16">
        <table name="X" type="X Axis" elements="40" scaling="MAFVoltScaling"/>
    </table>

    <table name="MAF Compensation #3" category="Fuel" type="2D" level="1" scaling="AirFlow16">
        <table name="X" type="X Axis" elements="50" scaling="MAFVoltScaling"/>
    </table>
52680015.xml
Code:
    <table name="MAF Compensation" address="5753a">
        <table name="X" address="615ea"/>
    </table>

    <table name="MAF Compensation #2" address="5758a">
        <table name="X" address="6163a"/>
    </table>

    <table name="MAF Compensation #3" address="575da">
        <table name="X" address="6168a"/>
    </table>
I settled on 1.39*stock values after starting at 1.48 (extra safe).

I'd just start at 1.4* just like tephra said. If you do the math, it works out:

area of circle: pi*r*r
inner diameter(stock): 2.8" (r=1.4)
inner diameter(primo): 3.3" (r=1.65)

area (stock) = 1.4*1.4*3.14 = 6.15 sq inches
area (primo) = 1.65*1.65*3.14 = 8.55 sq inches

conversion ratio (primo/stock): 8.55/6.15= 1.39

It is amazing how nicely the car runs on a maf this huge!
how are your trims after this? i mean the 1.39 thing..i'm planning to put back in aem's bigger maf housing..i'm just getting all the info first before proceeding.
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Old May 16, 2011, 02:42 PM
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Guys, I used 1.4 multiplier for 3.5 inch maf, the trims are within 1.5-2%, but there is a big quetion. The car iddles at 0.4 volts, and in the maf scaling table values for 0-1.02 volts are 0-s. So basicaly when we are multiplying those values by 1.4 we are gettion 0 at the end. Does this mean that we are not scaling the MAF in 0-1.02 volts area. Am I missing something ?
Last edited by YaroRS; May 16, 2011 at 03:21 PM.
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Old May 16, 2011, 07:40 PM
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check your formula/address for MAFV.

idle should still be around 0.8
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Old May 16, 2011, 09:09 PM
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Originally Posted by tephra
check your formula/address for MAFV.

idle should still be around 0.8
will check evoscan formula, but in Ecuflash even 0.8 v = 0 ? If I multiply it I will 0 obviously. So does this mean we are not adjusting those values ?
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Old May 17, 2011, 07:08 AM
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Edit: nevermind. I read wrong.


But if you have a ROM ID, I can make sure your logging address is correct.
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Old May 17, 2011, 08:55 AM
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Originally Posted by golden
edit: Nevermind. I read wrong.


But if you have a rom id, i can make sure your logging address is correct.
53050009
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Old May 17, 2011, 09:41 AM
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Installing a velocity stack on the 3.5" maf will help the idle voltage. When doing maf calibrations from scratch TRUST THE MATH.
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Old May 17, 2011, 10:34 AM
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Just for reference it appears that the MAF voltage starts to hit 5v at around 300 ft/sec of flow, which means these are the rough crank HP limits based on pipe velocity:

550 crank HP = Stock MAF
650 crank HP = 3" MAF
900 crank HP = 3.5" MAF

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Old May 17, 2011, 09:35 PM
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Originally Posted by YaroRS
53050009
MAF Volts should be at 23808F48.

You need to log 2 bytes and use "x/1024*5" for your eval.
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Old May 17, 2011, 11:25 PM
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yup thats right..

older versions of evoscan had the 1byte/2byte confused...
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