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Author Topic: Opinions: using KFLBTS vs LAMFA for fuel all the time?  (Read 385466 times)
Rick
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« Reply #75 on: October 07, 2011, 04:38:37 PM »

You can use BTS, but when the turbo is in it's spool zone, say below 4500 rpm, you would want lambda to be around 0.85 anyway.  Once above the boost threshold you're not going to see a measurable difference in spool whether you're at 0.78 or 0.85.

Rick
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nyet
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« Reply #76 on: October 07, 2011, 05:03:05 PM »

Agree 100% with Rick, as usual Smiley
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« Reply #77 on: October 13, 2011, 12:29:17 PM »

i dont feel like this thread has closure...


i dont have anything to add as I havent played with it much yet beyond building the axis map in my definitions and then changing it, but I still am asking myself why audi didnt use lamfa.  Or am I mixed up?

any setup tips on the map?  Say we change the axis to 0,20,40,60,80,100... then what?  Would filling all the values with 100 be just like when it was all 1s?   I have read this thread alteast 3 times and something just isnt clicking for me, when I look at the map I am not even sure what values i would want to build it with.  are the values lambda, AFR?  herp derp help please  Smiley
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nyet
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« Reply #78 on: October 13, 2011, 12:40:13 PM »

iSay we change the axis to 0,20,40,60,80,100... then what?  Would filling all the values with 100 be just like when it was all 1s?

Nope. Because if you don't fix the axis, LAMFA will ALWAYS be used if its lower than BTS, regardless of throttle position.

So the idea is, set up the "100" row to follow the curve you'd like to see based on rpm.

The problem is, you don't have a load axis, so you can't tailor it based on how "late" the driver mashed the throttle. IMO you really dont need to though. Just set it up so you get the fueling you want assuming the driver mashed the throttle WAYY before your boost really starts to build.
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« Reply #79 on: October 13, 2011, 12:55:17 PM »

holy crap, i need to go do something really basic and then come back to this.  I am really confused...

So currently I mash the gas and the engine starts to increase RPMs which increases my spool, builds boost and then the car fuels off calculated EGTs, which are off load(boost).  this is all part of the BTS stuff.  I have fueling figured out there and I have it so that as boost builds it drops basically from 14.7 at partial load to mid 12s and then to mid 11s as boost peaks and holds.

what will lamfa changes do for me?  i guess thats where my disconnect on this topic is happening.  is lamfa supposed to smooth something out in the transitions?  Is the goal here to prevent from going too rich too fast or the opposite.

I am sorry i am being retarded, i really just cant digest something correctly here.
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nyet
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« Reply #80 on: October 13, 2011, 01:07:55 PM »

I think the problem is, in order to get BTS to get you enough fuel soon enough, you have to set the load threshold pretty low... and then you'll have really shitty fuel consumption part throttle, when the driver *isn't* mashing the gas.

This way, you can set up LAMFA to get fuel going early, BUT ONLY if the driver mashes the pedal.

Then, you can use BTS for ONLY high load situations, regardless of pedal position.

Make sense?
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phila_dot
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« Reply #81 on: October 13, 2011, 02:46:25 PM »

Using BTS only without changing the temp threshold, I don't see enrichment until about 14 psi (K03's) sometimes.

I set the mrfa_w axis values to 50, 60, 70, 80, 90, 100. I am planning on installing my ZT-2 this weelend and I will try to get some logs up. The file I will be using will enrich via lamfa to 12.5 AFR and further enrich into the 11's as needed via BTS.
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« Reply #82 on: October 13, 2011, 03:16:21 PM »

YES!

Thank you Nye, now I have my head wrapped around it.  Thanks!
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elRey
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« Reply #83 on: October 15, 2011, 08:41:23 AM »

I think the problem is, in order to get BTS to get you enough fuel soon enough, you have to set the load threshold pretty low... and then you'll have really shitty fuel consumption part throttle, when the driver *isn't* mashing the gas.

(using boost in lieu of load, I know it's not correct but easier to follow)

So, what you're saying is that there are times when 12psi doesn't need enrichment and times when it does, right?

If BTS is set to enrich @ 11psi, then 12psi will ALWAYS see enrichment, even when it doesn't need it. Thus, bad gas mileage.

On the other hand, if BTS is set higher eg. 17psi, and LAMFA is used. 12psi will only see enrichment if driver smashes the pedal (i.e. when 12psi needs enrichment according to you).

And since LAMFA does have a RPM axis so you're not enriching at very low load, I can see your point.


note: I've always assumed EGT threshold for BTS would be set low in order to use it for main enrichment - for the poster that mentioned only seeing enrichment @14psi
« Last Edit: October 15, 2011, 08:43:37 AM by elRey » Logged
Tony@NefMoto
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« Reply #84 on: October 18, 2011, 11:20:06 AM »

I agree with nyet. The lambda enrichment maps for exhaust temp, knock, intake temp, etc all enrich based on a condition that has already occurred in the engine. LAMFA can be used to respond to the drivers input before the engine conditions have changed.
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« Reply #85 on: October 23, 2011, 01:21:57 PM »

Awesome. Finally got my fueling where I want it. LAMFA now anticipates peak torque without having to lower the EGT threshold too far. Notice the improvement the most on a long multigear pull... less knock under initial boost spike after a shift. Good stuff.
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« Reply #86 on: October 27, 2011, 03:36:14 PM »

Just out of curiosity's sake, what are you guys setting your MRFA_W values to?  I would like to revisit my enrichment method to use LAMFA a little more effectively instead of relying on BTS.

(on a ME7.5 1.8T)


Also curious what you're setting EGT threshold at and where you see enrichment from BTS at that point.
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masterj
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« Reply #87 on: December 05, 2011, 01:27:32 PM »

Nice topic over here Smiley Now one thing i do not understand yet is how to make my fuel mixture leaner when there's almost no torque request (idle for example)? Right now I'm using E85 with KRTKE +30% and o2 sensor is always keeping me at stoich, when i would like to have leaner mixture at idle and low rpm and richer mixture at high loads
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Rick
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« Reply #88 on: December 05, 2011, 02:05:34 PM »

you have to disable closed loop.
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masterj
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« Reply #89 on: December 05, 2011, 02:08:16 PM »

you have to disable closed loop.

so there's no other way? I mean, maybe there is some map which has lambda signal coefficient or something so i could adapt it for idle and on wot car goes to open loop anyway...
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