NefMoto

please for definition FKKVS map(function,meaning,axis etc.)

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.

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.

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

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?

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.

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.

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.

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.

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:


Specifically:

It is used to correct for fuel system pulsations and injector non-linearity.

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.

somebody help us tie KFLF into this discussion...

A4 b5's have a fuel return and b6's have a returnless fuel system.

The RS4 has FKKVS corrections because it's injectors are non-linear.
Once again people, FKKVS is used for linearization of the fuel system. Forget this "returnless" business, it has nothing to do with it.

what prj said.

ive named and used this map for injector linearization since about 1.5 year back.

i use FKKVS to counter STFTs.. the lambda-correction.
even tho the LTFTs show 0-0.3% and everything is set up right in TVUB and KRKTE, you can still have STFT fluctuations of +-10% or even more with some injectors without adding to the LTFTs, tuning FKKVS will fix this, and once corrected will generate very linear fueling.

I'm still not you are all actually dialing out fuel injector non-linearity. IMO you're generally dialing out MAF non-linearity.

If, on the other hand you have a fuel injector that you KNOW is non-linear and it can't be compensated for via TVUB, then fine.

PRJ: what non-linearity other than latency do you think you are correcting for?

Certainly pressure related non-linearity can't be compensated for by FKKVS anyway.

More importantly, when you are doing fueling corrections based on trims, how do you know if you should correct the MAF or the injector?

Injector non-linearity.
Please read about injectors and their parameters. Offset is something different to non-linearity...

Come on, this is first principles.

knowing the oem MAF and injectors were calibrated pretty much "spot on", and then swapping injectors ONLY, with a known MAF, intake tract etc tuned by the bosch-engineers.
once injectors = spot on after tuning FKKVS, and fueling is linear, i swap the MAF, tract etc and correct this one.. or the other way around.. one piece at a time.


TVUB can never compensate for non-linearity, that is voltage offset and adds to the OVERALL pulsewidth.. yikes.

what do you do when 14ms pulsewidth at 3000rpm gives you 10% less fuel then its supposed to.. but 13ms and 15ms gives you the correct amount..
well, you log injector DC, rpm, STFTs and O2s.. and you tweak the FKKVS accordingly.

Has anyone here logged a dead stock car with both a wideband and the normal variables?  I'm curious how spot on requested is with actual AFR on the stock calibrated hardware.  Anyone know?

On my RS4 it was bang on.
Then again, my RS4 is probably what you guys call Stage 3+.

On all the stock s4's i've logged, also dead on


Oh please. Stock RS4 is weak.

No. Latency is one component of non-linearity. For all solenoids, it is the single most dominant source of non-linearity. Look at any injector spec; they're most "wrong" at the bottom of their range, independent of duty cycle, and directly dependent (but also not linearly so) on pulsewidth.


Yes. So answer the question. It should be easy. What kind of non-linearity? If you *know* what it is, you don't have to tune empirically, which is what I said in my original post (but you edited it out).

And, as I pointed out, if you modified your MAF or intake, you definitely can't tune injector non-linearity empirically, because you don't know if your trims are non-zero due to MAF or injectors.

Says the person who probably never drove one :p

You really want to tell me that the only characteristic of an injector is flow and offset?

I am not going to bother arguing about this.

I've tuned them. On 91oct, you run out of injector almost immediately.

No. I said most (not all) of the non-linearity comes from solenoid latency

It makes 450 hp before you do.
And I am making 500+ on meth with IDC to spare.

I said 91oct. No meth. Not sure why you absolutely have to turn this into an e-peen contest. It's stupid, off topic, and counter productive. We all know exactly what stage3 cars can do. It isn't rocket science, and it doesn't take special ability to tune a K04 car, let alone a K04 car with meth.

You seen one K04 tune, you've seen them all.

Fuel. Timing. Boost. Not magic, not special pro tuner sauce. I definitely don't know what "before you do means", but like I said, im uninterested in e-peen contests.

(http://nyet.org/cars/images/2012-10-11-dyno-nyet/2012-10-11-2.png)

I never turned it into an e-peen contest, you just said a stock RS4 is weak, I just said that you have never driven one. And I was right :)
As for that dyno chart - there are a lot of things wrong with it - I've seen it before, and you can choose to believe in fairytales if you like, but this is irrelevant to this discussion.

Stock RS4 is weak. Like I said, not enough injector to run more than 18psi at redline. 350 wheel on 91oct, at best. Give it some real injectors, and it makes the same power as a k04'd S4. There isn't anything magical about the RS4.

Not sure where you got your information from about whether i've tuned one or not.


Obviously absolute dyno numbers mean nothing - the only thing that matters is relative numbers.

Would you like to see a chart from an RS4 on the same dyno?

(https://sphotos-a.xx.fbcdn.net/hphotos-ash4/285750_4669626345855_2105070972_n.jpg)

Gee, what is wrong with that fuel curve after 6000 rpm? Could it be the injectors are maxed?

Why are you so defensive? We're all on the same team here. No need to get all riled up.

I'm curious about that RS4 dyno. So the red line is dead stock, right?  Did you happed to be logging at the same time as the stock run?

I have no idea. It was the existing tune when we got the car on the dyno. I don't think it was stock.

Your RS4's fuel pump is probably dead or on it's way out.
I've run 20 psi at 95 IDC to redline on mine for close to a year, before I fitted a meth kit, but I have a 044.

312whp is 100% stock on RS4. Or there is something wrong with the car.
In fact if you maxed out IDC at only 18 psi, there is 100% something wrong with the car.

And I can surely say this, because I have mapped a few of them.
As for your dyno numbers - you don't make 500 crank nor 450 whp with 5-12 timing at the boost.
Instead of king kong banging on your chest, an experienced tuner would look at the numbers, realize that something is a miss and then inspect the base settings on the dyno that were made for that run.

However, this probably did not even occur to you. Nor do you care as long as you can wave your e-peen around.
I wonder what my car would make on that dyno, as I am running more boost and more than twice the timing than you are - on the "weak" stock injectors.

Could be. But i've done several other S4's with RS4 injectors, and they all ran out of fuel at 18 psi, a few with new fuel pumps (including 044)


What AFR?


I'm unsure of the original "tune". I'd guess from the fueling that it wasn't much different from stock. It might even have been stock. It definitely wasn't very strong. BTW stock S4s do about 200-205 wheel on that dyno.


Could be.


Road pull with ECUxPlot says around 400. Shrug. I'm actually uninterested in absolute numbers; I'm only comparing it with other cars on the same dyno. Honestly, I'm not here to say my car is fast. Just observing that rs4 injectors aren't as big as, well, bigger injectors. Go figure.


You're welcome to visit any time. I'd love to tune a few cars with you as well.

Well, I've tuned several RS4's and none of them ran out of fuel at 18 psi, unless you ran something like 10.5 AFR.
I run about 11.8-11.7 AFR on them to redline and there is enough room to enrich to 11.1-11.3, as that is what I run in BTS. 19-20 psi.
My point is just that something is wrong with that number. Either it was made in a low gear, the dyno had incorrect loading or there was overcorrection for some reason.
I've mapped enough 2.7T that I know they don't make that power at 5-12 timing and boost.
My RS4 runs 14-25 timing at 1.7 taper 1.5 and I would not rate my car much over 500 crank... Then again, I have up to 550cc of pure meth going into the engine (50/50 mix and 1100cc total flow.)
IDC stable at 95% and no EGT issues.

I am not trying to have a dig at you, I am all for people making power, it's just to me there is something wrong with that graph, and I don't like you saying that a stock RS4 is "weak" when clearly there was something wrong with fuel delivery on that car...