NefMoto

Before I start, I'd like to point out that I know how to search the forum and I know how to read and I know where the S4 Wiki is and I am not asking for someone else to tune my car.

Back Story: I bought a B5 S4 with VAST Stage 3 RS6 setup. The emissions is not properly coded out. I want to make my own tune. Hardware is as follows.

VAST RS6 Turbos
Bosch EV14 52lb injectors
Stock FPR
Walbro 255lph
RS4 MAF housing (hitachi sensor)
JFonz SMIC
3" Catless Turboback
Currently running a MBC set to about 23psi but can switch back to N75
**A bunch more irrelevant stuff**

Starting with Tony's Base Stage 3, I multiplied the MLHFM table by 0.9534948096885813

For the fueling I just directly copied nehalem's values from this post (http://nefariousmotorsports.com/forum/index.php?topic=320.msg27838#msg27838) to use as starting values.

Question time!
1. Is this a good start? Should I worry about implementing the RS6's right away?
2. Why are people using such different TVUB values in the EV14 thread?
3. Do you use Blocks 32 & 33 in VCDS to adjust idle and partial throttle fueling and then log your wideband to adjust for WOT fueling?
4. How rich should it get during WOT and full boost?

I'm trying to learn how to try and learn here...

My opinion is - and this is not to put you off:
1. Learn how a forced induction operates.
2. Then go fiddling with the electronics.
3. Learning on a Stage 3 car where everything is changed from stock while asking such basic questions as "what AFR should it run" is quickest way to tears. I'd personally start on some hardware that is less expensive to blow up.
4. Copy-paste is not tuning. Injector parameters you can get, but MAF you will have to tune through logging.

1. I'm fully aware of how forced induction operates  ;)
2. I am fiddling around with the electronics  ;)
3. I have a stage 3 car so I will learn on a stage 3 car  ;)
4. I copy and pasted injector STARTING values  ;)

Also, I am fully aware that AFR is critical to get right on a forced induction engine. I am also aware that under a lot of boost the AFR should be around the 12:1 area depending on different factors like how well the ICs work.

Allow me to ask a different question. If this was your car, with these specifications, how would you go about getting a base file setup?

If you have an RS4 MAF, use the MAF table from the RS4 file. You can't modify a hitachi MLHFM for use with a bosch sensor, the linearization sin't even close.

It's an Hitachi Sensor in an RS4 housing (83mm)

Then you have given yourself a head ache :)

Is there reason I shouldn't just scale the housing diameter as I described in the OP?

Changing everything at the same time is not smart, you will never dial it in "quite right" at this stage if you do.
If you assume that your injector parameters are 100% right, then you can try taking the base curve, multiplying it by something to get somewhere close, and then doing fine adjustments using logs and kfkhfm.

As for fuel - if you knew FI concepts, then you would also know that the mixture is mostly a tool to combat high EGT.
There is no huge difference in power on gasoline on the 5v engines until you go below 0.8 lambda or above 0.9, although with the latter your EGT's will be sky high very quickly.

There is no "ideal" mixture. You tend to pick something that is lean enough to not hamper the engine from producing power and rich enough to keep EGT's down. Once EGT's exceed a critical point, you enrich the mixture or reduce boost - whichever makes more power.
Where those points are heavily depends on hardware setup and fuel used. This is why anyone asking for an "ideal afr" in my opinion has no idea of tuning, and I tell them to familiarize themselves better with the concepts first.

I simply adjusted for the for the difference in MAF housing diameter and pasted in some starter fueling values. Did I do something wrong besides having no idea what I'm doing?

Considering this is your first experience with tuning you should start with a maf with a known transfer sheet. You're just asking to learn the hard way otherwise. Master the basics, then move on to more advanced aspects of tuning.

Adjusting for the difference in MAF housing diameter is never just a simple multiplication.

Hmm. It seems like it would be  :-\

Do you think it would be a good idea to find a 85mm maf housing, then start with Tonys file again? One less difference to worry about.

I would personally start with a stock file and understand every change you are making and why you are making it...

It is not hard at all to tune the MAF, but you need to LOG and then make changes based on the LOG.
Not by guesstimating numbers. You guesstimate once, then you log and see how it worked for you, and adjust the areas that need adjustment.
Rinse and repeat.

The reason why this is not as clear cut as you'd think is that the actual air measuring part of sensor can end up in different spot of pipe (not exact middle) which in itself changes the read out significantly. For a given total air flow in a pipe, the air moves fastest exactly in the middle and slower as it approaches walls. Placing sensor in different spots will give you different readings even though total flow is exactly the same.

What he said.

Also, the way the intake is set up, if you have bends before or after the MAF makes a difference.

I'm also working on getting my MAF correct and so far it seems as if it is just easier to change all the MAF mapping accordingly for the correct sensor and housing combo instead of just scaling for a larger housing and using the ori sensor and log log log...spend less time getting it right I guess anyway.

I don't understand how the MAF will be giving the ECU accurate readings if settings are gained via logging the MAF? I guess I haven't found that thread yet or something. I mean if I purchased a brand new MAF sensor and housing combo I can probably rely on its readings being 100% accurate as long as I transferred all the MAF maps accurately into my file.
 
If I took that brand new sensor out and put it in a different housing, what other parameters can I use to figure what the MAF should be reading @ x rpm?

If I know what g/s the MAF should be reading @ idle, how does that help me @ higher rpm?

Compare your logs with the new MAF to previous ones, tweak until everything lines up. This assumes you have previous logs.

That's why you change one thing at a time.

You take a stock maf in stock housing and tune the injectors to perfection.
After that is done, you change the MAF, and now since your injectors are calibrated, you tune the MAF.

If you change both things at the same time there is no way to know whether it is fully right or not.
That said, I am not convinced it's that important that things are always 100% "right". As long as the values are more or less on target and the car responds well, I don't see a problem. Does not really matter from a performance standpoint if your load is underscaled by 3% and injectors overscaled by 3% or similar.

It requires lots of experience to get such things to perform though. It is a lot easier to change one thing at a time.