NefMoto > Noob Zone > Noob Questions (Moderator: turboat) > 1.8t Stock -> VR6 MAF housing conversion
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Author Topic: 1.8t Stock -> VR6 MAF housing conversion  (Read 421 times)
rzyao
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« on: November 29, 2024, 08:58:21 PM »
2000 A4 1.8t ATW 4B0 906 018 P

I just finished installing a Frankenturbo and converting from the stock MAF housing to a 3 inch MK4 VR6 housing. I tried swapping MLHFM from an AFP engine (021 906 018 M) but the car is still running a bit lean at idle and rich when revving. Is there a better way to do this? Do I need to change anything beyond MLHFM? If it's just MLHFM, how do I get the correct values for my specific setup?
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prj
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« Reply #1 on: November 30, 2024, 01:12:29 AM »
It's not only the housing, in case of the VR6 MAF the element is different.
There are three different elements.
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rzyao
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« Reply #2 on: November 30, 2024, 06:26:53 AM »
Quote from: prj on November 30, 2024, 01:12:29 AM
It's not only the housing, in case of the VR6 MAF the element is different.
There are three different elements.
I'm aware the element is different, I've tried using the new MLHFM with both the VR6 and 1.8t elements inside the 3 inch housing.

When people do this swap, I believe it's common to reuse the 1.8t sensor, so there's got to be some way to do it properly.

I'd prefer to reuse the 1.8t sensor just because I know it's working, compared to the unknown VR6 element.
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prj
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« Reply #3 on: December 01, 2024, 01:15:45 PM »
If you want to use a random sensor in a random tube, then you need a flowbench to get an accurate MLHFM.
Everything you are doing right now is dumb. Buy a brand new Bosch MAF, done.

Is your time and life really that worthless that you want to spend hours upon hours of screwing with this over something like 50-60$?
And then when it goes bad, you're screwed again and have to do it all over again.
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rzyao
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« Reply #4 on: December 01, 2024, 01:52:21 PM »
Alright, you've told me what I probably needed to hear. However....

Swapping to the VR6 sensor/housing in the file with just MLHFM ported over still gives me a P0102 MAF too low code. Is this expected since the air velocity is lower? Can't test drive, but when I was driving earlier on the 1.8t sensor, it was overboosting and generally running kind of lean. Idle is the same.

P.S. in classic 1.8t fashion, it did get better after I found a vacuum leak

--EDIT--

Did some digging, looks like the CEL is a result of KFMLDMN (from http://www.nefariousmotorsports.com/wiki/index.php/ME7_Tuning_Information). My XDF doesn't have this defined, but I do have KFMLDMX. How do I adjust this map to make it run properly? Should I also find it from the VR6 file and copy that over? Will attach bin files in the next reply

I think the overboost is a result of a bad N75, unrelated issue since ME7logger shows a smooth MAF input. The lean issue is still worrying me though, once I get my wideband sensor wired correctly I'll attach a log (just need to find a spare O2 sensor pigtail)

Could my rough running just be the result of not adjusting KFKHFM after making the intake significantly wider?
« Last Edit: December 01, 2024, 05:20:29 PM by rzyao » Logged
rzyao
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« Reply #5 on: December 01, 2024, 03:28:46 PM »
My frankensteined 1.8t bin and a stock mk4 VR6 file I found which generously donated its MLHFM map to me, looking to transfer KFMLDMN as well
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prj
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« Reply #6 on: December 02, 2024, 03:16:16 AM »
Pressure test from turbo with everything connected (incl. the manifold) before tuning anything.

Otherwise everything you're doing in the ECU is a giant waste of time.
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rzyao
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« Reply #7 on: Yesterday at 07:45:56 PM »
Haven't gotten the opportunity to pressure test yet, but the car idles perfectly with the MAF unplugged. Tried flashing a stock bin with MLHFM from a VR6 file, and my fuel trims are all over the place but the car is close to being able to idle at stoichiometric, leaning out a bit under load. In another thread I found out that the offset for my MLHFM is likely wrong, so I moved it from 0x10D8A to 0x10D80 and now the car is running closer to normal. Haven't had the chance to do much driving, but is ~5% trim normal for idle and light load when messing with the MAF and intake? First time messing with fueling and I want to make sure I've figured out all of the business with MLHFM.

Moving MLHFM also appears to have fixed the MAF too low code, so I think the offset was actually wrong (plus, comparing to an 018CH, the same 0x30F8 appears immediately following the map, then 0xD007 which I assume is MLOFS?)
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tao13
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« Reply #8 on: Today at 12:13:29 AM »
keep your sensor from 2000 A4 1.8t ATW 4B0 906 018 P
put it into bigger maf housing
rescale mlhfm (dont forget the OFS)
this methode must work and will give you a good start to fine adjustemnt

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