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Author Topic: Has anyone actually ran a blow-thru maf setup?  (Read 5810 times)
Mythbuster74
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« on: April 17, 2014, 06:35:24 AM »

I've been searching around the forum a good amount about this topic and I seem to only find people talking about this but no one following through to the end. 

I have a 1.8t a4 and i'd really like to move the maf to the intake side of the motor so that I can worry less about leaks and intercooler tubes blowing off (which is a big issue currently haha).  I'm running a t04e turbo so i'd be maxing out the stock maf anyways.  Right now I have the maf disconnected and it actually runs pretty well but is finicky and from what i can tell isn't actually reading boost levels, which scares me.

There's a couple people near me selling pro-m mafs but they're calibrated for mustangs with varying injector sizes.  Would I just need to contact pro-m and ask for there data points for that maf and then plug them into the maf scaling table?  I think i can get one for $50-$100.  I haven't researched this part much because I haven't decided what my actual plan is yet.
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Snow Trooper
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« Reply #1 on: April 17, 2014, 10:01:59 AM »

Yes lots of people have.  Not sure what you read but I suggest reading more.
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vwmaniac
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« Reply #2 on: April 22, 2014, 01:04:31 PM »

im running a blow thnru on my vr6 turbo using me7.1.
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Mythbuster74
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« Reply #3 on: April 23, 2014, 03:51:41 PM »

Yes lots of people have.  Not sure what you read but I suggest reading more.

Your actually the only person I've seen that has used a blow thru setup.  When I searched through the forums for those keywords I only found mostly theoretical things.  How did it work in your experience?  Did you use a bigger maf or did you just use the stock one and let the flow go off the end of the axis?  I'm mostly worried about getting the idle and ltft's correct right now, later on I'll switch to a bigger maf.

Also if you know of any threads worth reading, point me in the right direction haha.
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Mythbuster74
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« Reply #4 on: April 23, 2014, 03:53:52 PM »

im running a blow thnru on my vr6 turbo using me7.1.

Vr6 swapped Audi or gti/jetta?  (Just curios)

And how does it work out?  I think that since your car is NA to start with it might cope better, but I have no info on this.
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Snow Trooper
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« Reply #5 on: April 24, 2014, 12:02:34 AM »

Basically, if you run most audi/vw sensors they will read low, you won't go off the axis as you put it (btw, the numbers are all arbitrary with scaling, its all how they interact with other maps, they can be low, high, stock, whatever) you just need to tune accordingly.  The issues with stock sensors is they were not designed to take pressurized air and they can not handle super hot air.

There are a number of aftermarket companies that make a generic maf intended for blow through.  These will all work with tuning, as in setting up the needed maps to have that primary load input for the ecu to function accurately and fuel accurately.
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Mythbuster74
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« Reply #6 on: May 03, 2014, 12:07:32 PM »

Basically, if you run most audi/vw sensors they will read low, you won't go off the axis as you put it (btw, the numbers are all arbitrary with scaling, its all how they interact with other maps, they can be low, high, stock, whatever) you just need to tune accordingly.  The issues with stock sensors is they were not designed to take pressurized air and they can not handle super hot air.

There are a number of aftermarket companies that make a generic maf intended for blow through.  These will all work with tuning, as in setting up the needed maps to have that primary load input for the ecu to function accurately and fuel accurately.

In your opinion is it worth it?  Most people on here stick to the normal draw thru but I see a lot of advantages to it.  I just don't wanna invest a lot into this and then still have a car that runs like it does now.
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prj
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« Reply #7 on: May 03, 2014, 04:00:43 PM »

Keep in mind that you must disconnect your PCV from the intake if you run a blow-through setup as otherwise there will be oil vapours very quickly on the MAF and the reading will be wrong…

IMO don't bother. Either run speed-density if packaging is difficult or if it is not then run standard setup MAF.
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Mythbuster74
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« Reply #8 on: May 05, 2014, 05:18:33 AM »

Keep in mind that you must disconnect your PCV from the intake if you run a blow-through setup as otherwise there will be oil vapours very quickly on the MAF and the reading will be wrong…

IMO don't bother. Either run speed-density if packaging is difficult or if it is not then run standard setup MAF.
I already have the pcv disconnected from the intake.

To me, it doesn't matter much which maf method I use to tune.  My main problem right now is that when I plug the stock maf in it runs super lean at idle, but bringing the rpms up some brings the afr's to a reasonable 14 or lower.  I have a forge splitter which worked fine stock.  I've moved to about 10in from the throttle body with the recirc hooked up.  Its possible I have a small leak after the maf but it can't be very big.  Any thoughts on this? (Its a draw through setup)

Since my maf setup gives me problems and I have to drive the car everyday, I've been driving with it disconnected.  The problem with this is after I get to 22lbs of boost the throttle closes and if it goes back up that high again it puts the car into a soft limp with no codes.  Throttle opening is limited to about 30% from what I can see.  Is that from going over the map sensor limit?  Or maybe torque intervention?  Although I doubt its that fast.
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Mythbuster74
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« Reply #9 on: May 05, 2014, 05:41:01 AM »

Actually now that I think of it, the map sensor isn't actually reefing anything according to the torque app.  It just sits at 29.9 in/merc.  With the maf plugged in it does read correctly iirc.
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