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prj
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« Reply #105 on: January 28, 2012, 08:44:10 PM »
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I feel this thread lacks a summary a bit.
Obviously I understand that everything can be done in many ways, after reading through this, but the factory approach has emissions as nr 1.
For an approach that favors power/torque more than emissions, I would based on my research:
Leave EGT threshold for LAMBTS close to stock, and use LAMBTS as it was intended, for component protection.
Use LAMFA, and make it mimic the driving pattern. Usually the driver will go WOT at low RPM's all the time, but it is a bad idea to enrich there, as it will hurt fuel economy. I would tune LAMFA to enrich to around lean best torque, over a certain RPM where turbo spool up becomes instantaneous, and where the driver does not go unless he is flooring the car.
To get from lean best torque, to rich best torque and a bit below it (around 12:1), I would use KFLAMKR/KFLAMKRL.
So during a WOT pull (obviously they are all combined, but to illustrate my idea):
14.7 to 13.3 - regulated mostly by LAMFA initially at high requested load and RPM > turbo lag threshold
13.3 to 12.3ish - regulated further by knock control
12.3 and lower - caused by component protection.
LAMFA is used to get maximum torque from the engine during high demand conditions and to reduce the initial onset of knock during gear changes, KFLAMKR/KFLAMKRL are used for further enrichment to make best torque and LAMBTS is used to protect engine components. This way the ECU is geared towards best torque in all high load/high rpm conditions, while still being economical and having good emissions when the car is being babied.
Just throwing some ideas around, feedback appreciated.
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« Last Edit: January 28, 2012, 08:49:32 PM by prj »
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nyet
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« Reply #106 on: January 28, 2012, 09:04:57 PM »
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fwiw i find that on 91oct you have to go a LOT richer a LOT sooner (well before peak torque) to prevent knock... more like 12-11.5
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TTQS
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« Reply #107 on: January 29, 2012, 04:28:50 AM »
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I feel this thread lacks a summary a bit. That's a good summary. I haven't had time to further analyse what method other than LAMFA and LAMBTS Revo has used to go below lean best torque at WOT but the lamfaw-lamkr method certainly seems valid enough (Tony uses it). I need to do a lot more logging when I get a new battery for my laptop, but lamfawkr_w isn't currently in the list of variables in ME7logger. Thanks for a good summary of the position. Once I've deduced Revo's strategy in full, I'll update the 'understanding tuning' guide with a summary of all the salient points of this excellent thread. TTQS |
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« Last Edit: January 29, 2012, 04:34:43 AM by TTQS »
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prj
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« Reply #108 on: January 29, 2012, 04:52:49 AM »
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fwiw i find that on 91oct you have to go a LOT richer a LOT sooner (well before peak torque) to prevent knock... more like 12-11.5
Yea, I know. But I am in Europe, and I have 93 everywhere. And you never really "prevent knock", it's always riding the limit anyway. You don't gain much by going richer than 12. The additional advance is negated by slower flame speed inside the cylinder. |
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nyet
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« Reply #109 on: January 29, 2012, 10:39:27 AM »
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Agreed. Especially on 91. "prevent" is definitely more the wrong word.
On 91 oct, you need that much fuel preemptively just to STAY above 0 degs at peak tq.
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prj
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« Reply #110 on: January 29, 2012, 09:04:42 PM »
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On 91 oct, you need that much fuel preemptively just to STAY above 0 degs at peak tq. But you are not gaining really gaining much (if anything) by running it that rich. As you get richer than about 12.2 flame speed starts to decrease. Going richer means that while you can add more timing than before, you actually *need* more timing than before to make the same power, because laminar flame speed is decreasing and thus PCP occurs later with the same timing advance. Sure, slightly richer mixture has the benefit of cooling the cylinder, but at some point you will get to the 50 cent "get rich or die trying" scenario. If you try varying mixture levels on a dyno while adjusting timing to suit, at some point you will hit the barrier, you will also see, how there is almost no difference between 11.5 and 12.0 at knock limited MBT, so in that range you tune for best EGT. Your EGT's will eventually go up as well when going richer, as fuel starts burning in the EM... Sorry for the nitpicking, just sharing some experience  |
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« Last Edit: January 29, 2012, 09:07:43 PM by prj »
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nyet
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« Reply #111 on: January 29, 2012, 10:26:33 PM »
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thanks for the advice... i will definitely try to back off to 12 AFR again, but on my car, i was making more power from more timing all the way to 11.5 on 91oct.
i also tried less peak boost, but that also didn't work.
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s5fourdoor
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« Reply #112 on: January 29, 2012, 10:35:52 PM »
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Hi - I like the theory discussion, very fascinating. My experience is much like Nyet's, WOT AFR's higher than 12.0 seem to exaggerate timing interventions. Certainly we'd all like to minimize the extra richness required to run safely, but I tend to err on the side of precaution while tuning this safety margin item.
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nokiafix
Full Member
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« Reply #113 on: January 30, 2012, 08:03:22 AM »
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Hi - I like the theory discussion, very fascinating. My experience is much like Nyet's, WOT AFR's higher than 12.0 seem to exaggerate timing interventions. Certainly we'd all like to minimize the extra richness required to run safely, but I tend to err on the side of precaution while tuning this safety margin item.
I have noticed the same with a few 1.8T AMK & BAM engines, when going richer to 11.9:1 - 12:1 I tend to get more timing correction than 12.4:1 at the top end. Used to keep adding fuel to reduce CFs, but over the last year or so I have found its not always the case. I tune via LAMFA 99% request set to 1 just over 3000rpm then .89 upto 4500rpm then .84 to the red line, then all other load point over 75% I will tune to .91 upto 4500rpm and .85 to the red line. All values below 75% set to 1 and .89 over 5000rpm. Then KFLBTS to dump me to .81 with egt threshold set to my own findings, stock manifold, stock cat stock exhaust a lower trigger vs performance manifold and full turbo back exhaust a temp higher trigger. I find the 1.8T engine make better power and run less correction the closer i get to 12.4:1 |
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prj
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« Reply #114 on: January 30, 2012, 12:31:38 PM »
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I think this is where I like Tony's approach a lot.
I also added LAMFA to the tune and gave initial WOT enrichment via LAMFA to about lean best torque from 3000 rpm.
The result should be that it gets initial WOT-enrichment from LAMFA, and then the rest of enrichment is LOAD and knock based.
It starts a bit leaner than rich best torque (12.6) and gets richer with knock.
I keep LAMBTS as intended for component protection only with a fairly high trigger.
This way the ECU basically tunes it's own fuel and timing to maintain 11.6-12.6 AFR. It just rides the sweet spot
EDIT:
Edited some rescaling info, as that affects other maps.
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« Last Edit: January 30, 2012, 01:11:47 PM by prj »
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nyet
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« Reply #115 on: January 30, 2012, 01:18:00 PM »
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prj: i agree on the whole with your approach (and Tony's approach).
All I am saying is that rich best torque isn't rich enough for 91oct if you expect to get ANY timing at peak torque.
On 91 oct, you have to pre-emptively go super rich. I know, it sucks, but thats 91oct.
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« Last Edit: January 30, 2012, 04:22:00 PM by nyet »
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s5fourdoor
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« Reply #116 on: January 30, 2012, 03:52:27 PM »
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prj: i agree on the whole with your approach (and Tony's approach).
All I am saying is that rich best torque isn't rich enough for 91oct if you expect to get ANY timing at peak torque.
On 91 oct, you have to per-emptively go super rich. I know, it sucks, but thats 91oct.
oregon 91-92 here and also not a fan of it... can somebody write a concise methodology for tuning via "tony's method?" i'll re-read but again, as prj mentioned, this thread doesn't seem complete yet... food for thought. the rs4 has a TABGBTS threshold of 700... the stock s4 has a TABGBTS threshold of 500... so my gut feeling tells me prj's ideas are right, but i get the same nasty interventions that nyet experiences. |
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prj
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« Reply #117 on: January 31, 2012, 03:39:07 PM »
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The RS4's TAGBTS is 750, not 700. I've logged it quite a bit now, since it's my daily hack  The TAGBTS comes from turbocharger specification. The K04's were engineered to withstand higher EGT temperatures than K03's AFAIK. It's really there to protect the turbos. |
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nyet
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« Reply #118 on: January 31, 2012, 04:27:25 PM »
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This is what I dont get: how does going super rich protect the turbos |
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s5fourdoor
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« Reply #119 on: January 31, 2012, 06:35:04 PM »
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This is what I dont get: how does going super rich protect the turbos lol, its quite counter-intuitive. truth is that you are adding more fuel to an explosion. LOL.... |
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