NefMoto

I recently started tuning my car's ECU for an efficient and more powerful boost profile. After doing a little research, I decided to peek at one of the tuned files in the subforums here (namely the mbox 91 oct stage 1 bin). I was looking at the KFMIRL values and was comparing them to my stock ones and something just didn't make sense to me. In the stage 1 mbox bin, all of the values for '0%' (from 400 rpm to 7000 rpm) are above zero. This seems odd to me because wouldn't it mean that there is always going to be load requested, even if you are at idle or off of the gas? Could this be a potential wear issue for the turbo to have load requested at all times, or does it not matter since it is such a small amount (around 7 or 8 for each rpm increment).

Please, school me if my thinking on the matter is wrong. I know a lot of work was put into that mbox file, but values other than 0 for 0% just don't make sense to me.

Calling the torque "requested" is kind of a misnomer, it should really be called "maximum possible requested" torque is anything. Your foot and henceforth  the throttle position really dictates current actual torque and that's what really matters.

In the context of tuning, the KFMIRL map is nothing else than a limiter of maximum possible torque at any given RPM/load request.

you can put 500 everywhere and the only issue you will have will be that the car will be very jumpy off the bat since the ECU won't moderate turbos anymore and will try to make the most boost/torque all the time when there is enough load to actually move turbos which is pretty much when you step on it significantly.

Well, today, while testing non-zero values for the 0% row, I noticed that I had about 2hg less vacuum (about 20.5 when normal for me is 22 or 23) than normal and that I could also hear my turbo trying to spool while the SAI was on while warming up (foot off of the pedal). I'm going to reset those values to 0 and see if those two things go back to how they were.

Am I right in thinking that KFMIRL is used to dictate what load to give at a certain RPM and pedal position, and then LDRXN sets a limit on the maximum allowed load for a given RPM? It seems like if you mess with KFMIRL too much and set values too high for partial pedal position then you are not going to get the fuel you need to support the boost it is providing. Is this where you would need to dial in the fuel to compensate for the added boost at a partial pedal position?

http://s4wiki.com/wiki/Tuning#Boost

Yes, I've read (and loved) the wiki many times, but I was looking for a more in-depth description than what was provided in there. The info in there is incredibly helpful, but I was trying to get a better feel for how the map works so I could file it away neatly in my brain. For now, through experimenting with various values, I have figured out what values are working best for myself and my car.

Thank you for the help, I'm sure I'll have some better questions as things progress.

Have you read the MDFUE module yet?

http://www.nefariousmotorsports.com/forum/index.php/topic,555.0title,.html

Unfortunately, I have not gotten to LRDLMX (contains map LDRXN) yet, but the translated PDF should give you a general idea.

Don't get me wrong, I think there should be more discussions like this, but its really late and a general understanding of the Funktionsrahmen is the best place to start.

Yes


No.  KFMIRL does not need adjusting for upto 1.2 bar boost. The max load requested here is 190, which is roughly 1.2 bar.  Your MAF and injector calibration control the fuelling, KFMIRL has nothing to do with it.  My car runs 22psi currently.  To do this, I increased the requested load to 210 at  the 100 percecent requested torque.  For requested torque of 50% and above, i increased the requested torque by the same percentage.  For example, 100% requested torque was 190, now is 210.  That's roughly a 10% increase.  If 50% requested torque was 90 load, then it should be increased by 10% to 99.   

This ensures you have a smooth linear throttle and boost response.  You should ONLY touch KFMIRL if you need more than 1.2 bar of boost, otherwise leave it.  Use LDRXN to cap the boost/load. 

The MAF will compensate for any extra boost with added fuel - unless you go off the scale.

Rick

Phila - Thank you for linking me to those modules! I will have to go through them when I'm done with exams at school.

Rick - That makes a lot of sense. Looking back at what I said earlier made me realize that I wasn't taking into account that the MAF would still be metering all of the air that is coming into the system and adding fuel as necessary. Thanks for clearing that up for me. Also, I thought that KFMIRL was requesting quite a bit of load stock, so LDRXN must be working as I first believed. I was kind of hoping to be completely backwards about something because I'm running into some weird surging issues when I'm getting to 15-16psi or so, but I'm thinking it may be a hardware issue or limitation of some sort.

Don't guess. Log.