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MAF scaling.. which data to relay on?


lepich

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For scaling purposes, you should set AFR to something richer since your MAF scaling is off. Your MAF scaling looks dangerous.

yes, it way off. i use drop-in KN filer, strange why it is so off from off-shell MAF scaling for a drop-in.

There are no bad people, just differeent.
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You are running way too lean...but you have enough info to scale the upper portion of your MAF scale.

 

Use Airboys sheet..you basically determine what the % error is between your target ARF (11.4 in your case) at each data point and maf V. Assuming there are no leaks, right now you are pulling in more g/s than your scale is seeing. You need to bump up the maf scale amounts accordingly.

 

Just watch your WB02 afrs...like MickeyD said, that is dangerously lean.

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yes, it way off. i use drop-in KN filer, strange why it is so off from off-shell MAF scaling for a drop-in.

 

Not unusual at all. I think enthusiast saw the same thing with just a purolator filter. Swapped back to OEM and everything was fine.

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Heres another handy spreadsheet tool from cobb. It has injectors scaler, intake calibration and some other stuff. Got to the intake calibration tab and there is a formula right under the Cobb logo that is pretty handy. Simply put in the requested and the actual AFRs and it tells you the multiplier to apply to correct the difference.

 

http://www.cobbforums.com/forums/images/AccessTUNERCalibrationTuningGuideWorksheetforSubarusv131.xls

 

There are some other semi-relevent Cobb tuning documents here(worded for StreetTuner not RR tuning):

 

http://forums.cobbtuning.com/forums/showthread.php?t=31091

Let's kick this pig!
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Ok, here is an update with a question, as usual :-)

After I've scalled MAF for OL, car runs great. with Meth, I am targeting 13.5-14.5 AFR in some areas, getting 12-12.5 on most WOT area.

However, at 3600 - 3800 RPM, 3.2 load still getting 11.5 -11.9 AFR (14.47 targeting there) .

If I would like to have 12-12.5 AFR there, is there is another way to make it lean, beside OL table? I do not have room for adjusting OL anymore, can't have more that 14.7.

 

So, I am thinking to change MAF scalling, lower g/s numbers in that area (3.8-4.0v), so ECU will inject less fuel in order to hit AFR target. Does it sound right? Can't think of any other way to make it run leaner.

There are no bad people, just differeent.
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Yes, I have scalled MAF without Meth, was hitting my OL AFRs.

Now, tuning for Meth, need to raise target AFR, so real AFR will be in 12-12.5 range.

But in some areas I cant rasie it anymore.

So, if I change my MAF to a lower airflow values, ECU will think - less air, less fuel needs to be injected. As a result, my real AFR in that area will go leaner.

 

Actually, I've tried this, and it works . 12 AFR with meth where I need it. Just not sure if this the best way to get AFR leaner.

There are no bad people, just differeent.
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I am trying to scale my K&N Typhoon right now. For closed loop I'm using RR tab for MAF.

 

Just want to make sure I am scaling for open loop low range correctly. I set WGDC to 0, using the simplified primary open loop fueling, with most of the targets at 11.0.

So I log at various speeds, 5th 50-70% throttle, and 3rd WOT. Lets say with my lc1 I see AFR of 11.2, target 11.0. So difference of 1.8%, I would then multiply the corresponding Mass Airflow g/s by 1.018 for that volts cell right???

 

How close, percentige wise, is good enough for scaling?

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^ Yes, for OL I did almost rthe same. except i did only WOT, from 2K to 7K RPMs.

several runs, corrected using these excels I've posted above, adjust, runs againa,.. 4 times like this.

 

Now need to do CL scalling, RR is not showing anything for me at that Scalling TABfor soem reson. will look into it closely

There are no bad people, just differeent.
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If you're injecting a lot of meth, you'll have to adjust you MAF values to compensate as you cannot target AFRs leaner than 14.7 to reach your target. A few others have done the same thing you're suggesting. I didn't have to as I'm running less meth than most (mainly because my Perrin system cannot handle anymore.

 

 

Yes, I have scalled MAF without Meth, was hitting my OL AFRs.

Now, tuning for Meth, need to raise target AFR, so real AFR will be in 12-12.5 range.

But in some areas I cant rasie it anymore.

So, if I change my MAF to a lower airflow values, ECU will think - less air, less fuel needs to be injected. As a result, my real AFR in that area will go leaner.

 

Actually, I've tried this, and it works . 12 AFR with meth where I need it. Just not sure if this the best way to get AFR leaner.

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