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Tuning for 3" MAF housing

6K views 43 replies 7 participants last post by  1turbofocus 
#1 ·
I currently have a MAFia and a stock MAF with a draw-through configuration.
I'm moving to a 3" housing and blow-through with no MAFia.
I know this will end up being a drastic change in the MAF Transfer table, which I can handle.
What I'd like is a suggestion on a starter tune for adjusting to the 3".

My thought was to reload the MTF and manifold volume back to stock, and then add 10% fuel to the MTF just to get started and see how it runs.
Perhaps load a 5%, 10% and 15% richer MTF tables into the xcal to save some time.

So my questions:
1) What can you all suggest as a starter MTF for the 3" housing?
2) What oddities should I expect to run into? (aside from leaner AFR due to lack of metering of the extra air)
3) Will any idle functions need adjusted?

All tips I'm looking for are regarding N/A tune.
However, if anyone has a suggestions for boost and 3" MAF tube I'll welcome those too.
My plan is to run with the wastegate open until the base tune is where I want it.
By then I should have enough data to make educated adjustments to the upper portion of the MTF table and start running boost again.
I should also mention my car is already tuned for 9.5psi boost with the draw-through setup.

Thanks all. [wrenchin]
 
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#43 · (Edited)
Thanks again to Tom for his help with my tune.
I have the SCT Pro Racer Package, and it was great to see how Tom tunes first-hand.
I approve 100% of how he does his tuning, and would recommend him to anyone.

Now, as for my 3" MAF issue: I could only get it to work properly when I used the stock air straightener and tuned it open loop.
For whatever reason it will not run well when attempting to use both the MAF and STFT.
Now it's running quite well and making more power than ever.

The reason I couldn't get a good reading from the 3" MAF was due to my pipe configuration.
Even though I had 10"+ of straight 3" pipe before the MAF there was a 2.5" 90* bend before that which opens up to the 3" pipe.
My BOV is mounted in that 90* bend, which also causes turbulence.

If I removed the MAF from the bend and ran it open it would idle and rev fine.
As soon as I put the MAF back the idle went erratic and the car would stumble like crazy.
The air straighter helped considerably, but still wasn't enough until I tuned it in open loop.

Bend:


Air straightener:
 
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