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Author Topic: KVB fuel consumption constant  (Read 18235 times)
carlossus
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« Reply #15 on: March 29, 2011, 04:11:54 PM »

The rising rate fuel pressure regulator handles keeping the fuel pressure the same relative to the intake pressure.

Perfect, thanks.
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nyet
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« Reply #16 on: March 29, 2011, 07:12:10 PM »

Perfect, thanks.

As an aside it is common to put boost gauges on the FPR pressure line... which is where the FPR gets the "reference" manifold pressure.. and which might be different from MAP readings, since the MAP is pre-throttle plate.
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TTQS
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« Reply #17 on: April 05, 2011, 05:43:04 AM »

Hmm. Well I just calculated my offset from the six refuels since my remap and the average was 111.1% and there was good cluster around the mean.

So I plugged in my laptop and VCDS and followed the procedure I uploaded only to find that I couldn't test the new value. Instead I got an ERROR message. I checked back with the original remappers to see if they locked out any access to change adaptation channels and the answer was no.

I'll try logging in to the ECU see if that makes a difference, but I'm not hopeful. Maybe an e-mail to Ross-Tech will shed some light on it...

TTQS
« Last Edit: October 22, 2011, 02:40:41 AM by TTQS » Logged
carlossus
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« Reply #18 on: April 05, 2011, 06:09:49 AM »

Do you need to log on with your Security Key code (SKC) first? Just a punt.
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TTQS
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« Reply #19 on: April 05, 2011, 07:12:27 AM »

Do you need to log on with your Security Key code (SKC) first? Just a punt.

Well I eventually got it to accept 110 so I suspect that despite the pop-up windows telling me the value could go up to 115, I suspect that (on my ECU at least), the limit is 110.

Some hours later...

Another go reveals that it will accept 115%, so perhaps it can only deal with 5% increments which isn't very useful because that leaves a choice of only 105%, 110% or 115%. I've e-mailed Ross Tech support to see what they say.

TTQS
« Last Edit: October 22, 2011, 02:40:53 AM by TTQS » Logged
Tony@NefMoto
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« Reply #20 on: April 05, 2011, 01:38:09 PM »

Did you try using Lemmiwinks? Lemmiwinks bypasses the limitations imposed on the adaptation channels and writes directly to memory.
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TTQS
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« Reply #21 on: April 05, 2011, 02:34:33 PM »

No, I haven't progressed beyond VCDS just yet.

Andy at Ross Tech replied requesting an Auto-Scan log to see which controllers the car has got and whether there are any fault codes which I've just supplied. There were no unexpected fault codes, just historic stuff relating to an alarm activation and a faulty brake pedal switch which I replaced several months ago.

I don't think this will shed any light on the situation. I also had a problem with installation of the VCDS drivers but deactivating my anti-virus software sorted that. Full of hope, I tried again with the fuel consumption correction, but still the same result. Sad 10% is good enough, but it would be nice to get to the bottom of this.

TTQS
« Last Edit: October 22, 2011, 02:41:41 AM by TTQS » Logged
nyet
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« Reply #22 on: April 05, 2011, 05:48:29 PM »

FWIW i didn't bother to "derive" my KVB from first principles. I just filled up to a full tank, reset the MPG trip, drove till it was empty, refueled, calculated my actual MPG, compared it with trip MPG, and changed KVB by the percentage error.

Only had to do it twice, and it converged fine after two tweaks.
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Please 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 experience.
TTQS
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« Reply #23 on: April 06, 2011, 12:52:53 AM »

Andy at Ross Tech confirmed that the factory repair manual states that the increments are indeed 5%, not 1% (for the TT 8N at least) as allowed by VCDS, so it would appear that you would be better off adjusting KVB to get the displayed fuel consumption to read correctly.

TTQS
« Last Edit: October 22, 2011, 02:41:50 AM by TTQS » Logged
carlossus
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« Reply #24 on: May 26, 2011, 06:42:35 AM »

Well I corrected KVB after running a few tanks for MPG calculation.

I was quite suprised that the error was 24%. I hadn't previously checked, but looks like my tune had not  corrected KVB for 3bar -> 4bar fpr conversion.

So the reality is that I'm averaging mid 20's for a stage1 1.8t. It got me thinking a bit about the big name tuners. There is such a wide range of mpg's banded about on the cupranet forum (20s to 40s) that is largely populated by APR, REVO and Custom code tunes that I wonder if these guys make any correction at all from stock?
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julex
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« Reply #25 on: May 26, 2011, 04:59:50 PM »

I'll add to this thread.

Standard KVB value can go only up to 776cc injector size due to reaching the maximum value it accepts.

To accommodate injectors larger than that you have to also change FKVA "Constant conversion factor for consumption display", S4 Mbox 8bit at 0x1A4D5, conversion 0.062500*x.

This is a multiplier for KVB. I have it at 2.00 in my tune and KVB around 500 to accommodate my 1000cc injectors. It works Smiley

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BDK
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« Reply #26 on: May 26, 2011, 05:52:37 PM »

I can't tell you much about the constants and formulas as you guys are way out of my league but in the vag-com method since the adaptation is done through the clusters adaptation channels I'm pretty sure the base calculation is in the ecm but the correction adaptation is done in the cluster.  

If I'm right flashing the ecm won't affect your correction factor even if adaptation channels get reset and it means even if a tuner locked out any channels in the ecm you'd still be able to adjust it.  

In addition I don't think lemmiwinks would allow greater than normal tolerances as I believe it only works on kwp2000 me7 ecms, most if not all of the clusters I have seen are kwp1281.  

However, I'm not sure if all clusters support this function as the documentation I've seen doesn't always mention it depending on the car.  you may be able to make adjustments manually to the clusters eeprom and write them back though as I suspect they are visible somewhere in a binary file if you played around a bit to locate them.  This method may allow greater than normal tolerances if needed 

If there is a login required to access the adaptions channels in the cluster 13861 is the only login I know of, other than the skc to reach channel 21 for key programming in an immobilizer car. 
« Last Edit: May 28, 2011, 08:34:25 AM by BDK » Logged
julex
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« Reply #27 on: May 26, 2011, 09:53:11 PM »

stuff

No pun intended but please, use paragraphs if you want people to actually read what you're saying.

And yes, each cluster has a small adjustment range to accomodate off-fueling system that might come out of factory. But this is peanuts, I think around 10% either eay or so.

Most high HP cars like run of the mill Stage 3 is already 2x over factory power with fueling system delivering around 200% (in case of 660 cc injectors) or slightly less than that of fuel. Cluster doesn't hae enough range. Binaries for ECU need to be changed for cluster to show MPG accurately....

or you can leave it as is, enjoy virtual 100% Smiley
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BDK
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« Reply #28 on: May 28, 2011, 08:44:40 AM »

Sorry about my crappy grammar.  You were right.

I wasn't implying that the vag-com method was the end all fix.  I realize you guys get way outside normal tolerances.  I just wanted to correct a couple misconceptions I read in the thread.
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NOTORIOUS VR
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« Reply #29 on: July 15, 2011, 08:05:29 AM »

I'll add to this thread.

Standard KVB value can go only up to 776cc injector size due to reaching the maximum value it accepts.

To accommodate injectors larger than that you have to also change FKVA "Constant conversion factor for consumption display", S4 Mbox 8bit at 0x1A4D5, conversion 0.062500*x.

This is a multiplier for KVB. I have it at 2.00 in my tune and KVB around 500 to accommodate my 1000cc injectors. It works Smiley



Arg! Thank you! lol... I was all confused why it wasn't going higher... then I figured there was a limitation on the value itself.

Thanks for the tip.. I'm going to try that now.
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