Is the MAF the limit?

[486] · Jan 29, 2015

hatemi said:
Why not do it properly and change the MAF, linearization and diagnostic limits. Thats whats holding you back.now.

I've changed the map that robnitro refers to to get the smoke maps working above 1000mg/str, I haven't seen anything about raising the amount the computer can see, though.

I'll have to reread the thread, maybe I missed it.

ETA: reread the thread, unless further developments were made elsewhere, scaling the calibration is the way to read airflow past 1275mg/s

[486] · Feb 1, 2015

Code:

map axis V	3” linear	2.5” linear	3” linear 50%
1	1650	995	825
0.954	1319	818	660
0.918	1107	699	554
0.882	929	598	465
0.846	780	510	390
0.811	658	435	329
0.776	555	371	277
0.741	481	315	241
0.707	415	268	208
0.673	348	228	174
0.638	295	191	148
0.612	264	168	132
0.578	221	142	110
0.54	178	116	89
0.507	146	96	73
0.475	119	79	60
0.446	98	66	49
0.418	80	54	40
0.39	65	44	32
0.362	52	35	26
0.337	41	28	21
0.32	35	23	18
0.288	25	16	12
0.271	20	12	10
0.245	15	8	7
0.148	3	-8	2
0.123	2	-13	1
0.105	1	-17	1
0.068	0	-25	0
0.048	0	-31	0
0.025	0	-38	0
0	0	-47	0

So, with some help from the smart fellows in the GCC section of pirate 4x4 I was able to use the excel to make a reasonable approximation of a proper linearization (I hope)

The first column is the values in the axis of the map, the next three columns are the data, for the 3" MAF housing, then the stock 2.5" housing, then the 3" MAF housing scaled by 50%.

The computer has a diagnostic limit of 700 kg/hour, calculates out to 1167 mg/str at 5k RPM, fine for a plebian build, and just about the max that the 2.5" sensor housing will read to anyways. The 3" housing will allow the sensor to read 1650 kg/h, so that's some good capacity, but unusable without scaling as the computer refuses to see the light of airflow values above 700kg/h.

Thus the 50% scaled data, the sensor's apparent range is much more in tune with what the computer expects to see, you just scale your smokemaps' axis data by the same amount to compensate. Everyone's happy, and it'll now read an actual value of 2333 mg/str at 5k RPM, with no screwing around with the other maps, as the computer thinks it is really "just" 1167mg/str, which is well within the other 1275mg/str diagnostic limit

ETA: installing the 3" MAF body some time soon with the unscaled linearization to see if it is a good fit, got some datalogs with the stock MAF to compare to.

[486] · Feb 2, 2015

Right, got the volvo MAF body stuffed in there, not a good choice of donor vehicle, had to get really hacky to get it in there. Anyone who's looking for one should grab one from a later model 2.5 or something.

The linearization values look proper, it is reading about 40mg/s higher at idle, but that is most likely caused by turbulence from removing the "air horn" from the MAF inlet, as it was interfering with fitment of the MAF in the airbox cover. It smacks up against the 1275 limit in the same spot. Gonna load the scaled values tomorrow.

[486] · Feb 9, 2015

Finally got the scaled values in there and ran it again. Everything looks proper, at idle it's reading as it should (around 260 or so, so 500ish actual), on the absolute high end that the log shows, it runs through 670 mg/str of air, impressive, right? It is a little bit neater when you remember the values are scaled 50%, so 1340 mg/str

Next up is to screw with the pump voltage maps to hopefully get some more fuel so I can use the "new" air. Maybe time for the 12mm pumphead.

arazvan2002 · Jun 19, 2016

robnitro said:
I may have phrased it wrong. Pressure- resistance to flow is what makes more and more air flow through the somewhat restrictive C screen. If it were less restrictive (no mesh with angle as in C maf screen), it would be easier for the air to flow through. But when you go with a bigger and bigger housing, the air has less tendency to want to flow through that path?
Just thoughts... I'm an electrician (technician) by trade... so I'm thinking like ohm's law... if you have a really strong connection, that will take most if not all the current, compared to a small wire on the same potential. Of course it is nothing like air, and even water is not like air, lol.
To get rid of the 1000 mg/s limit that the smoke map looks at:
Open vagsuite and your file
Click search map content
Just hit ok. You get a big list. (some bug it doesnt find the map even when you enter a value from the map)
Click length to sort by length
Look for maps that have hex 140 length (or decimal 320)
On mine it is called 3D "blablablabla" C01C "blabla"

It has temp on top , left is values of 10000 etc, and map same values as the left. C01C seems to be common on other files, so that might help.
Right click, edit Y axis.
Change the upmost value from 10000 to 15000. Hit save.
Hit save on the map, and hit read. Make sure the 15000 is there.
Now replace that row with 15000.
Hit save, hit read. Do the same for all 3 maps that are similar.

Here is my map from vagsuite for MAF linearisation. I have to change the axis tot 15000 where now is highlighted 10000. Ok. What to do with the value that's now 1071?
I have already modified diagnostic limits for maf to 1500 but I don't know if I can use more than 1071 in smoke map.
For the moment I'm running on MAP smoke but for sure is a little laggy with it and the boost is not the best way to do it. I need to burn 75mg from 2750rpm to 4000 with ARL injectors.

ketchup · Jun 19, 2016

This isn't the map Robnitro is describing. You're looking for a 3d map in the long list of un-named maps

nicklockard · Jun 19, 2016

To the limit

arazvan2002 · Jun 20, 2016

I found the map, but is discovered already in my version of VAG Suite and newer EDC Suite (continued project of VAG Suite).
I check few files for AWX, AVF, ARL and that value is already 15000. For ATD wich had smalled MAF housing, is 10000.

This means that I can use more than 1071 values in Smoke limiter? In logs on channel 3 I can see only just 876 for requested MAF but I have the whole EGR map flat 1000, the highest value in IQ by MAF is 1500 (instead of 1051). So what's wrong.

ketchup · Jun 20, 2016

I don't think the values in the MAF linearisation map are mg/stroke but are possibly kg/hour? I didn't touch the MAF linearisation map and I don't think you have to.

I raised diag. limit from 1275 to 1500, extended the smoke limit axis and changed the map above like you have. I ignore requested MAF as I have no EGR. I just observe/log actual MAF.

Strange you're only seeing 1051. Have you extended the smoke limiter map axis?

arazvan2002 · Jun 20, 2016

I can see 1500 in actual because I extended diag limits. I will ignore the requested column and calculate my smoke map with real maf values in axis. Thanks

Sent from my HTC One_M8 using Tapatalk

Roma9009 · Feb 3, 2021

robnitro said:
Ok, scoured the A4 damos in winols and found the 2 switches that turn into MAP based smoke limiter. I also found the boost correction temperature map settings... it tells the smokemap by MAP when the air is "less" due to heat or more due to cold. Those numbers you see below explain it.

Manual MAF to MAP smoke limiter
Maf setting
05AD60: 03 0C 00 00 00 01 01 00 01 01 01 00 00 00 01 01
Map setting
05AD60: 03 0C 00 00 00 01 01 00 01 01 01 01 01 00 01 01

Your address may vary.
In Vagedcsuite, open your file, Click view file in hex. Click search, click hex. Type in 01 01 00 01 01 01 00 00. You will find it 3 times (manual, auto, auto). Those last two 00's should be changed to 01 01 if you want to do MAP based smoke limiter. Do it for all 3 to be sure, unless you know exactly the offset of your maps.
Hit save on top, hit verify checksum on top of vagedcsuite.
Then edit the smoke limiter by MAP:
Manual IQ by map (VAGsuite shows it in the unknown maps.
Example, smoke map manual is address 5c9ec (279372 in decimal mode)- this is at 5cd50 (380240 in decimal) for my ECU. You will see that it is filled in with 5000 or 5500, its IQx1000 for the values... and the top is pressure, side is rpm. You can change those values.

Also the boost correction by temperature should be adjusted if you want IAT to regulate fueling (hotter air is less dense!).
You can copy my map, I got the values from a PD that used map limiter- it calculates correctly (I double checked the values with an online calc), and they use 50C as a center point. Make sure you change the temperature axis and pressure first, hit save, read, before putting in these values!

Here's my maps... it's set for around 16.5-17.5 afr, but 51 mg on my tune turns out to be more like 75 or so... so its around 1.4-1.5 x off... if you are running different nozzles, you should tune it for WOT smokefree, then scale back the other values- maybe a little less iq if you want more afr for lower end (economy).

In maf logging, I saw that with a proper functioning maf, MAF (mg/s)= 480 x (abs boost in bar). In higher rpm it drops, because its harder to push air in. If you run a less restrictive turbo, it might hold 480mg/s per bar higher up.

Good day! Please tell me how to fill in the smoke map? I switched MAF to MAF, found card 380240, all indicators are 5000. How to fill it in correctly? Thanks.

Is the MAF the limit?

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