NefMoto

Hey guys,

I have been lurking on this forum for quite sometime, but tried to avoid going this route. A las, I have come to the point where I feel it might behoove me to learn from the knowledge you guys have gained and so freely shared.

My car currently runs ev14 52lb injectors @ 4 bar, 90mm MAF. I see the base stage 3 tune circulating on this forum is for 60lbers with a smaller MAF.

I figured by now someone would have probably started work on migrating to a 90mm/52lb setup. I would really appreciate if you could share your map with me, so that I can have a base to start with.

Otherwise, any solid suggestions for converting from the nyet base would be helpful.

Thanks.

if you currently have a tune with the 52lbs and 90mm, just read out the bin and post it up, from there you can learn how to modify and code certain sensors out.

I'm pretty sure in his tune everything is moved around... so it's not of too much use.

Welcome! You can read and post your tune. I'm not sure we'll be able to make much sense of it, but we can try. You'll probably end up starting from scratch like I did, it's easier in the end.

Read this to get started and familiar with the tools/software you'll need:

http://www.nefariousmotorsports.com/wiki/index.php/Getting_Started

Then read Nye's tuning wiki article to familiarize yourself.

http://s4wiki.com/wiki/Tuning

Start with a stock M box file.

MAF scaling:

I have an 83mm RS4 MAF housing and originally attempted to scale the stock MLHFM MAP by calculating a correction factor:

73mm (stock MAF housing) / 83 (RS4 housing) = 0.8795

I then multiplied all of MLHFM by 0.8795. This worked ok, but my AFR would vary between gears.

So I redid the MLHFM by scaling from Tony@Nefmoto's 85mm MAF housing file. Copy Tony's MLHFM then calculate the correction:

85mm (stock MAF housing) / 83 (RS4 housing) = 1.024

Then multiply the whole table by a correction. This seemed to work better for me. You will calculate using 90 instead of 83, obviously. Try either of these routes and see how they work for you. I still have a stock KFKHFM MAF correction table.

Injector scaling:

You will want to get the datasheet for your injectors, if possible. You will need to edit KRKTE and maybe TVUB.

There is a calculation for KRKTE although a few of us have kind of just been estimating it and altering the value based on LTFTs. My gasoline 60lb Deka @ 3 bar KRKTE was 0.101, for reference.

My 1000cc EV14s came with a datasheet. I used the dead time specs for TVUB. When I had 60lb Dekas I used a stock TVUB.

I think your scaling math is wrong :)

1) you want to scale UP for a larger maf
2) you have to scale by the area, not the diameter

so, technically, it is (85*85)/(73*73) = 1.355

Isn't the area of a circle pi(radius squared)?

yes, but pi/pi is 1 :)

to be clear, if r=d/2:

pi(D0/2)^2/pi(D1/2)^2 = (pi/4)/(pi/4) * (D0^2/D1^2) = (D0^2/D1^2)

make sense?

For the example given, from 73mm to 85mm:

3.14(42.5*42.5) = 5671.625
3.14(36.5*36.5) = 4183.265

5671.625 / 4183.265 = 1.355

Got it.

I think recalibrating MAF for new tube can't be as simple as multiply by any constant value.
Regargless how this constant was estimated.
And this was many times confirmed by live experiments.
As example compare MLHFM curves for Bosch S4 MAF and 1.8T 150ps ME7.5 400BB (4B0906018AL or similar)
Both MAF using the SAME insert-sensor and differs only in tube diameter.
What about this?


   

Yes. Its a terrible approximation... but without a flow bench, there is no other way to calibrate it.

I've tried it both ways and gotten better results with your first method, similar to tony's stage 3 base file, and then tweaking kfkhfm.

The "first" method isn't really a method. Its totally wrong. It is equivalent to an unscaled MAF file (albeit less unscaled than totally unscaled)


you mean after tweaking KRKTE :)

tweaking both actually.  and i know it's not correct, but i was getting way higher numbers than I should have on the top end... so i massaged the top and bottom of mlhfm and then used kfkhfm to fine tune along with krkte

Out of curiosity, how high? Until recently, I have been running an unscaled MAF file (with an 85mm MAF) and im in the process of scaling it.

So, I tried this MAF scaling. So far so good. I have not made any MAF corrections yet, still unsure of the process, but WOT fuel is a lot more consistent in gears 2-4. Thank you for the correction/suggestion.

always seemed to go rich... i can't remember, and those logs are long gone.  I'll give it another go with using the correct way and see if i can get some better results.   I've figured out a few other things since then, so maybe i was just being dumb.
Sometimes people just need to slap me around a little to make me see what's up.
I'll report back... might do some 85mm testing tonight and see what i come up with... starting with all 1's in kfkhfm.  I have very consistent fueling now using the other "nonway" and everything jives, but i hope i can get a little better results using the r^2 .

Do you have this data handy? I'd love to see what Bosch does for tube diameter scaling!

I just dug around a bit, and it seems the scaling should be done by diameter, and not area, in MLHFM? It looks like I was operating on some bad assumptions about the units of MLHFM.

Comments?

Sorry, I never got any logs back from my test file... someone got a bike.
Did u look at an rs4 vs an abox maf?
I think that's why I got better results using diameter vs. Area scaling.

Not sure, but I just went to diameter scaling and my KRKTE is more or less where I would expect it should be for my injectors. I can't explain why, but if it works, it works.

Little help here please... I am going to be installing the vast performance 90mm intake elbow into my car and my question is... when scaling my maf I want to scale by diameter right? according to nyet.
So does that mean I just take 90/73 = 1.2328767123287671232876712328767 which is what I would multiply my MLHFM table by right?

I guess what I need to know is if this is the right approach?
AND
What decimal place should I round my number to?

3 decimals is more than sufficient.  i believe you wan to start with tony's stage 3 mlhfm and multiply by (90/85)

Next question... If I want to migrate ev14 52lb injectors into my current tune do I just have to alter TVUB and KRKTE? For example I found a stock m box bin that is fueled with ev14's so can I theoretically take the TVUB and KRKTE values from that bin and add them to my bin? Or is it more complicated then that?

If the bin used 52# ev14's you can simply copy the tables...

Which tables though? Just TVUB and KRKTE?

approx. fuel pulse = load % * krkte+ tvub
you have to copy both or your ltft's won't be close to centered.
after driving for a tank of gas, take your LTFT's and search for my dynamic excel tool to help you recenter your KRKTE and TVUB values.
what air intake setup are you using?  its likely you need to set FKKVS, KFLF, and KFKHFM to constant 1.00 even if you are running the stock airbox.

are you using a bosch or hitachi sensor?  assuming hitachi.

I will be using a bosch sensor in the vast performance 90mm intake with open element filter on the end..
so copy both the krkte and tvub values over and then I should be good right? or do I have to calculate something?

So today I added my 90mm vast maf housing to my tune and after installing and reflashing I went for a test drive and noticed one thing... Before I upgraded to the 90mm maf housing my boost gauge would spike to ~23 psi and hold 20 but now I am only seeing a 20psi spike and holding ~17-18 psi. Is this because my maf scaling is slightly off or what?