eazydaz
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« on: November 06, 2012, 12:18:32 PM »
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please for definition FKKVS map(function,meaning,axis etc.)
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s5fourdoor
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« Reply #1 on: November 06, 2012, 12:36:18 PM »
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rpm versus pulsewidth in ms.
values represent the multiplicative modification of the pulsewidth calculation.
for instance: 1640 rpm / 6.00ms if you have a value of 1.00 then nothing occurs. if you have a value of .9 then
for your car: pulsewidth effective = pulsewidth calculated * .90 thus you are injecting less fuel than was calculated.
don't tune with FKKVS until your KRKTE and TVUB are set to your car for near-zero LTFT's with the car fully warmed up.
also don't tune FKKVS to try and mask a cold-start leanness issue. there are tables for that too.
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« Last Edit: November 06, 2012, 12:39:10 PM by nehalem »
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eazydaz
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« Reply #2 on: November 06, 2012, 12:50:53 PM »
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can this map cause problems with rpms? after remap I have problem with slow descent,sometimes when I pressed clutch when I shifting,rpm´s remain standing 3-6seconds,or when I put foot down from gas pedal,engine start brake after about 5seconds
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s5fourdoor
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« Reply #3 on: November 06, 2012, 01:20:48 PM »
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can this map cause problems with rpms? after remap I have problem with slow descent,sometimes when I pressed clutch when I shifting,rpm´s remain standing 3-6seconds,or when I put foot down from gas pedal,engine start brake after about 5seconds
this can absolutely be related. although, if i had to guess, the inaccurate fuel mixture during engine vacuum conditions is causing the timing to get cut and / or lambda control to adjust itself to attempt to get the engine into good closed-loop range. it sounds like your krkte and tvub aren't accurate yet and you are getting some type of intervention. maybe it's even torque monitoring, but honestly - i can't comment any more than i have because i'm close to speculating... i know that for my car when krkte and tvub weren't near correct it ran like total shit, especially during part-throttle lift-situations in the vacuum operating range. the "eletronic throttle" becomes very noticable when things aren't tuned correctly, because the car does NOT respond how a poorly tuned throttle cable car would. it sort of bucks and gives non-linear judders which confuse the driver, expecting some kind of linear response to a linear throttle push. |
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« Last Edit: November 06, 2012, 01:23:07 PM by nehalem »
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eazydaz
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« Reply #4 on: November 06, 2012, 01:32:02 PM »
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otherwise engine running good,only problem is the rpm´s slow descent,when I flash original file,every is ok..car was remap on dyno maha lps3000,anyone dont know where is the problem
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catbed
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« Reply #5 on: November 06, 2012, 01:42:29 PM »
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rpm versus pulsewidth in ms.
values represent the multiplicative modification of the pulsewidth calculation.
for instance: 1640 rpm / 6.00ms if you have a value of 1.00 then nothing occurs. if you have a value of .9 then
for your car: pulsewidth effective = pulsewidth calculated * .90 thus you are injecting less fuel than was calculated.
don't tune with FKKVS until your KRKTE and TVUB are set to your car for near-zero LTFT's with the car fully warmed up.
also don't tune FKKVS to try and mask a cold-start leanness issue. there are tables for that too.
Isn't this map used for injector correction for returnless fuel systems? So there should be no need to touch it if you use a return system right? |
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k0mpresd
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« Reply #6 on: November 06, 2012, 01:44:25 PM »
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unitronic modifies it in there s4 stg2+ (k04/stock injector) files.
this map is the route i was planning on taking for this w8 turbo im about to start work on. fuel trims are only a little off using stock injectors @ 6psi.
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prj
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« Reply #7 on: November 06, 2012, 01:54:06 PM »
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Isn't this map used for injector correction for returnless fuel systems? So there should be no need to touch it if you use a return system right?
No. I use this map to pull fuel for my meth system, as it's IDC based and this is the best map to do this. |
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catbed
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« Reply #8 on: November 06, 2012, 02:41:42 PM »
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No.
I use this map to pull fuel for my meth system, as it's IDC based and this is the best map to do this.
"According to Bosch documentation, FKKVS is for compensating for pulses in returnless fuel system. This could be why it is all 1s in M-box, since S4s do not have returnless fuel systems." Grabbed that right from the wiki. Why is the map all 1.00 in my B5, and in B6s they are not? Not trying to argue here, just genuinely curious. |
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masterj
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« Reply #9 on: November 06, 2012, 02:43:18 PM »
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"According to Bosch documentation, FKKVS is for compensating for pulses in returnless fuel system. This could be why it is all 1s in M-box, since S4s do not have returnless fuel systems."
Grabbed that right from the wiki. Why is the map all 1.00 in my B5, and in B6s they are not? Not trying to argue here, just genuinely curious.
FKKVS is always used in ecu calculation. You can disable it by setting all 1s or use it to fix fueling |
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catbed
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« Reply #10 on: November 06, 2012, 02:48:07 PM »
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FKKVS is always used in ecu calculation. You can disable it by setting all 1s or use it to fix fueling
I understand that, I'm just wondering what bosch meant for this map to be used for. |
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s5fourdoor
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« Reply #11 on: November 06, 2012, 03:24:51 PM »
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injector's didn't always have super-clean linearity and low pulse-width response/recharge ---- whatever the technical term is someone help.
therefore perhaps older injectors required fine-tweaks. prj - for instance - said he like's to use this map for methanol fueling adjustments.
i'm assuming that means he likes to take the bottom right hand of the 16x16 matrix, say the lower-right 4x4 surrounding his WOT pulsewidths.
my guess is that it's a map designed to allow the engineer one clean opportunity at a high-level in the motronic system to semi-accurately increase / decrease fuel in the range surrounding a "problematic pulsewidth".
potential case in point. the k-box from the rs4 has more resolution at low pulsewidth. in fact, the fkkvs is used on the stock rs4 tune.
the injectors used in the stock rs4 were probably non-linear at low pulsewidths. i can't guarantee this, but audi uses the table on the best and latest factory tune - which to my knowledge - had a return-less fuel system as well.
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prj
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« Reply #12 on: November 06, 2012, 03:52:53 PM »
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I understand that, I'm just wondering what bosch meant for this map to be used for. The FR are posted on this site, why don't you just read them? The english translation is horrible, the german text is much more accurate: FB RKTI 11.40 Funktionsbeschreibung
Die Funktion berechnet aus der relativen Kraftstoffmasse rk_w,rk2_w und dem Faktor frkte die effektive Einspritzzeit vor
dem Feinabgleich tevfa_w, tevfa2_w. Bei idealem Kraftstoffversorgungssystem m¨usste mit diesem tevfa_w + tvu_w, tevfa2_w + tvu_w
ein Lambda von 1.0 im Brennraum entstehen, bei Vorsteuerung auf Lambda = 1.0 und Neutralwerten aller Gemisch-Adaptionen.
In der Praxis kann durch Nichtlinearit¨aten von Einspritzventilen bzw. Pulsationen im Kraftstoffkreislauf eine Lambdaabweichung
auftreten. Diese Abweichung in Abh¨angigkeit von Drehzahl nmot_w und effektiver Einspritzzeit tevfa_w, tevfa2_w
werden ¨uber das Kennfeld FKKVS korrigiert. Die korrigierte effektive Einspritzzeit ist te_w, te2_w. Specifically: In der Praxis kann durch Nichtlinearit¨aten von Einspritzventilen bzw. Pulsationen im Kraftstoffkreislauf eine Lambdaabweichung
auftreten. Diese Abweichung in Abh¨angigkeit von Drehzahl nmot_w und effektiver Einspritzzeit tevfa_w, tevfa2_w
werden ¨uber das Kennfeld FKKVS korrigiert. It is used to correct for fuel system pulsations and injector non-linearity. |
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marcellus
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« Reply #13 on: November 06, 2012, 04:26:37 PM »
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rpm versus pulsewidth in ms.
values represent the multiplicative modification of the pulsewidth calculation.
for instance: 1640 rpm / 6.00ms if you have a value of 1.00 then nothing occurs. if you have a value of .9 then
for your car: pulsewidth effective = pulsewidth calculated * .90 thus you are injecting less fuel than was calculated.
don't tune with FKKVS until your KRKTE and TVUB are set to your car for near-zero LTFT's with the car fully warmed up.
also don't tune FKKVS to try and mask a cold-start leanness issue. there are tables for that too.
Why would you mess with FKKVS if your KRKTE and TVUB are set and your LTFT are near zero? Well, other than the meth example. |
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nyet
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« Reply #14 on: November 06, 2012, 05:47:16 PM »
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Why would you mess with FKKVS if your KRKTE and TVUB are set and your LTFT are near zero? Well, other than the meth example.
If you hit max ps_w, you can still compensate in FKKVS ... not that that is the right way to do things... Or, if you are running out of pump, but it does have enough juice to get you over the edge if you just bump up FKKVS enough... Both examples are probably bad tuning practices, though. So yea, if you have to tweak FKKVS, something is up with the rest of your tune and probably isn't set up right... unless you know for a FACT your fueling system is so jacked that you cant model it correctly with only KRKTE and TVUB... and you're pretty confident your KFKHFM is correct. |
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ME7.1 tuning guideECUx PlotME7Sum checksumTrim heatmap toolPlease do not ask me for tunes. I'm here to help people make their own. Do not PM me technical questions! Please, ask all questions on the forums! Doing so will ensure the next person with the same issue gets the opportunity to learn from your ex
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