S-AFC2 Based Tuning Question

[mnetwork]

I have got my turbo and all the other mods I needed (except for the manifold that's on back order).. anyway, on Sat I decided to put the S-AFC in to get that over with and I was playing with it today. I'm going to put my 680 injectors in before anything and leave them in for a week or two to get the feel of tuning so when I get the turbo it won't be all new to me. Getting to the point.. I was playing with it a little today and I am using the "Definitive Piggyback Tuning Guide" and I had a question about the one part to make sure I understand it correctly...

...Since the STFT directly effects the LTFT, then you can just add the two together, and tune from there. For example, if the LTFT is +20%, and the STFT is -5%, you are at approximately +15%.

Is the above just what it says? Do I always look at the two values and add them to make zero? It doesn't really mention the STFT after this, it just says to look at the LTFT. And should I be waiting for the LTFT to change for a certain amount of time before I make my adjustment on the S-AFC, because this doesn't exactly change quick? I just need this cleared up, I'm just a little confused.. Thanks.

 

[eclipse_gst_99]

There is good information here. http://www.dsmtuners.com/forums/showthread.php?t=58403

 

[mnetwork]

Um, that is what I said I was using... I need clarification on it as I mentioned above...

 

[out there]

i haven't tried using the fuel trims to tune... i'll try that when i get home next week.
i technique that i've used was very simple... i just figure out how much bigger my new injectors are and then figure out what percentage cut will even out the fuel.
example:
680-450=230
230/680=33.8%
experiment with how much fuel you remove, but it should drive just fine at -33 or -34 for low throttle. my high throttle is not much more than than just because i still have the stock turbo and don't boost higher than 20psi (in cool weather).
if you still have the stock turbo and everything was running fine before... try putting the 680s in, set it to -33 or -34 across the board and see what happens

 

[kawboy]

i haven't tried using the fuel trims to tune... i'll try that when i get home next week.
i technique that i've used was very simple... i just figure out how much bigger my new injectors are and then figure out what percentage cut will even out the fuel.
example:
680-450=230
230/680=33.8%
experiment with how much fuel you remove, but it should drive just fine at -33 or -34 for low throttle. my high throttle is not much more than than just because i still have the stock turbo and don't boost higher than 20psi (in cool weather).
if you still have the stock turbo and everything was running fine before... try putting the 680s in, set it to -33 or -34 across the board and see what happens

Good Advice, but also remember, he has the stock turbo which is a 14b which can boost to 20psi, while you have the t25 which will only safely boost to 16psi. Therefore your fuel trims on high throttle should be a bit lower than his.

 

[mnetwork]

So just doing that calculation should take care of the low throttle settings? And I assum you just tune for knock in high throttle because your a 1st gen... Any advice on high throttle for 2nd gen because I have to tune for timing advance..

 

[mnetwork]

Good Advice, but also remember, he has the stock turbo which is a 14b which can boost to 20psi, while you have the t25 which will only safely boost to 16psi. Therefore your fuel trims on high throttle should be a bit lower than his.

And why would that matter.. at low throttle the turbo doesn't have any effect on the car anyway.. wouldn't that only matter at high throttle??

 

[kawboy]

Yea, I was talking about high throttle, if you re-read it

 

[mnetwork]

Sorry, didn't see that

 

[mnetwork]

What would you recommend the Ne-Points and Throttle Points to be set at.. I wish I could just go 1k, 2k, 2.5k.. etc, but you can only raise the rpms in 200rpm increments. And I keep hearing different things about the throttle points, I don't know what I should use..

 

[mnetwork]

Anyone have their own input on afc tuning?? I basically need to know how to tune low throttle and what to set my ne-points at..

 

[GVR4592]

Tune the low throttle according to the guide. It's very straightforward. Get your fuel trims correct before you do anything with the high throttle. Anybody that says not to use fuel trims doesn't understand what they are doing.

More Safc tuning:

http://www.roadraceengineering.com/newafc.htm
http://www.roadraceengineering.com/newafcsetting.htm

http://www.dsmtuners.com/forums/showthread.php?t=111005&highlight=tuning+guide

 

[mnetwork]

Tune the low throttle according to the guide. It's very straightforward. Get your fuel trims correct before you do anything with the high throttle. Anybody that says not to use fuel trims doesn't understand what they are doing.

More Safc tuning:

http://www.roadraceengineering.com/newafc.htm
http://www.roadraceengineering.com/newafcsetting.htm

http://www.dsmtuners.com/forums/showthread.php?t=111005&highlight=tuning+guide

I don't understand the Definitive Piggyback Tuning Guide though.. I don't unerstand how STFT comes into play. It mentions that you add the two to make 0, but STFT is always chaning and do you wait for LTFT to change after adding or removing fuel? Also, after that it never mentions STFT again. It just says to look at the LTFT and make it 0. I just need this little part explained to me..

 

[out there]

you don't need much adjustment for the low throttle, because it's the same all across... unless you feel like experimenting to get more "driver-friendly" below 2000rpm (with a 3" pipe mine feels a bit odd).
with the high throtte, tuned for knock and o2 voltage; timing was my last concern. i just set a generous amount of fuel (after increasing boost), then followed the butt dyno and o2 voltage to lean it out until knock started showing up. the ne-points make it handy to adjust fuel all the way up the curve.
personally, i set mine pretty rich a little past where i normally shift so that i have less fear about doing damage should i forget what i'm doing (and who hasn't? )

 

[mnetwork]

I'm going to have to tune low throttle when I get my injectors and I just need someone to explain that concept in the Piggtback Guide...

 

[mnetwork]

I just need help tuning using fuel trims. I need an explanation on the correct way to tune low throttle using fuel trims so I can understand..

 

[CanadianTSi]

Get your STFT to 0 or as close as possible for each rpm value up to 4kish and then just carry that setting all the way up.

 

[mnetwork]

Get your STFT to 0 or as close as possible for each rpm value up to 4kish and then just carry that setting all the way up.

So I don't use the LTFT??

 

[CanadianTSi]

Not to tune your low's no, if your STFT is always around 0 your LTFT will come down over time as well.

 

[mnetwork]

So when does LTFT come into play??

 

[mnetwork]

Any comments on this?

 

[mitsugst97]

here is a question for you, why does the RRE guide say to start at +39 on low setting with 550 injectors? (on a 2g) i was thinking it should be slightly under 0. and then on the next example it starts at -2. I can't possibly see the adjusting screw and honeycombs making that much difference.. is that a typo?