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Changed XDS & starting vibration vcd settings, significantly less gas mileage.

rcnacura Sep 8, 2016

  1. rcnacura

    rcnacura US Spec 8V

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    http://www.audi-sport.net/xf/index.php?posts/2811776

    For those that were interested in this. Preface, I did change my rims to 20inch also, but filled up my tank today and usually get about 24mpg per fill up. This fill up I got 17mpg for this tank with 80% sport ads city driving. I log all my gas mileage manually.

    Changed the XDS along with the starting vibration. Will set them back and see what the next tank gets but so far I've felt an acceleration difference ever since I've changed the XDS. Think this is definitely pushing more power to the rear first on aggressive starts causing the lowered mpg.

    Anyone else seeing this that have changed the vcd settings?
     
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  3. Rob2k68

    Rob2k68 Well-Known Member VCDS Map User

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    Interesting feedback - I wonder which change has reduced your mpg? I've also changed XDS to the middle setting, moderate I think, and will be fuelling up in the morning. I just brim it and then work and mileage done given the litres it needed to fill.

    Could it be that the 20 inch wheels have messed up your ODO readings - how does the rolling radius compare with what you had fitted before ?
     
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  4. Rob2k68

    Rob2k68 Well-Known Member VCDS Map User

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    It does seem to put the power down better though :yahoo:
     
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  5. rcnacura

    rcnacura US Spec 8V

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    Went from the stock 18 to 20. Roughly around the same weight and overall dimensions of previous tire circumference.

    And yes car puts the power down, just differently now. I think I set the XDS to the rs3 level (maximum maybe, I forget but will check tomorrow).

    When I refilled I only had 5 miles left showing on the trip computer, so it was about 13.5 gallons.

    Sent from my SM-N910V using Tapatalk
     
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  6. Rob2k68

    Rob2k68 Well-Known Member VCDS Map User

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    That's brave trusting the fuel computer to 5 miles !!

    You're talking U.S gallons then ;o)
     
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  7. rcnacura

    rcnacura US Spec 8V

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    I've driven about 20 more miles when i just got the car looking for a has station while it showed 0 before so I know there is some reserves. Most nerve racking experience ever ! And ya us gallons.

    Sent from my SM-N910V using Tapatalk
     
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  8. Rob2k68

    Rob2k68 Well-Known Member VCDS Map User

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    Just fuelled up - same 280 miles per tank as usual so I don't expect the XDS setting to be the cause of what you are seeing.
     
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  9. rcnacura

    rcnacura US Spec 8V

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    So weird stuff going on, but changed everything back to stock and the car feels a lot faster, like how fast it felt prior to the changes. Changed the Steering back to normal and the XDS to weak instead of medium.

    When I floored the gas with the XDS/Steering settings, the car would go fast, but just didn't feel AS fast. With the settings back to stock, the "butt-dyno" makes the car push you back into the seat far more. Kinda weird.

    Maybe because the car was trying to put the power down to all 4 tires with a better power distribution, thats why the car felt less quick, compared to having more of the power going to the front and then to the rear? Did quick a bit of aggressive acceleration "test" too along with highway passing and it feels just like when I had the smaller 18 inch oem rims.

    Going to play around a little more with changing the steering settings independently, then the XDS independently to see if any of those have correlation. Will report back.
     
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  10. Rob2k68

    Rob2k68 Well-Known Member VCDS Map User

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    That does sound kinda both strange and interesting - you probably read the same as me the the Golf R and RS3 have XDS to moderate by default - I think it definitely gets the power down better but still have wheel spin changing up to third gear.

    Changing things one at a time sounds like a good plan.
     
  11. rcnacura

    rcnacura US Spec 8V

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    Its interesting also that there is deactivate setting for xds. Wonder if this essentially makes the car a front wheel only car?

    So did another acceleration "test" while going into corner, traction control definitely killed power and the light came in after the corner and letting off the accelerator. This being on default factory settings. Will have to find an empty parking lot to do better test.

    Sent from my SM-N910V using Tapatalk
     
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  13. rcnacura

    rcnacura US Spec 8V

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    Think I figured it out, which makes better overall sense.

    Set the xds to maximum/strong and there was no difference in how the car felt on hard acceleration - No lowered power output feel.

    So that makes me believe that the steering adaptation was sapping power because it was trying to prevent crazy launches/wheel spin by removing throttle input and/or applying the brakes.

    Speaking of brakes, when I did change the xds, the car smelled like something was burning a little bit. Don't know if it was the car or just a surrounding vehicle.

    Going to change the steering adjustment to max to see if that lessens computer intervention on hard acceleration since lowering increased the "nanny" correctors.

    Sent from my SM-N910V using Tapatalk
     
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  14. 73pop

    73pop Registered User

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    Anybody found this in vcds
     
  15. vamos

    vamos Registered User

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    Would be interested if that smell was the brakes slightly cooking - that could be the esp applying braking to wheels it detects as spinning - hence reducing the power to that corner.
     
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  16. rcnacura

    rcnacura US Spec 8V

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    Find the XDS coding at: http://www.audizine.com/forum/showt...ne-Options?p=11823682&viewfull=1#post11823682

    Another observation from setting the XDS to "Strong", the front of the car lifts far higher than before on launching/hard acceleration. This is allowing me to believe a significant amount of power is being sent to the rear first instead of the front. Going to try some launches "Not activated (think this would make the car act as FWD only), and weak since I've tried Standard, Medium and Strong.

    Lastly, this would also really change the need for aftermarket sway bars since I'd think you could obtain more oversteer instead of understeer because power is being distributed "better".
     
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  17. Rob2k68

    Rob2k68 Well-Known Member VCDS Map User

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    Interesting test results - thanks for this.

    I have Eibach ARBs front and rear and can vouch for those - they're also two position adjustable.
     
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  18. S3 Turbo

    S3 Turbo Registered User

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    Thanks guys for testing this out!

    Been really curious myself.

    I understand it as xds medium or strong makes a significant difference.

    How about starting vibration reduction.
    Did you notice any improvement, and if so what setting are you using??

    Also worried of getting very little or no TCS+ESP intervention during an emergency situation as some posts on other forums suggest. Don't know if correct... Get conflicting information on this one...

    Also I understand it as this makes most traction gains on a gti or other fwd car but less significant with awd?
     
    Last edited: Sep 11, 2016
  19. Rob2k68

    Rob2k68 Well-Known Member VCDS Map User

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    I have XDS at medium which I considered low risk given that I'd read that the 7R and RS3 have this setting as default.

    It certainly seems to get the power down better so I think it'll be a keeper.
     
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  20. S3 Turbo

    S3 Turbo Registered User

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    Sweet!
    Really tempted to do this.

    Have you changed the starting vibration reduction setting as well or keeping at stock?
    (My safety concern was mainly on this one.)
     
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  21. vamos

    vamos Registered User

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    As a lay man I could imagine in a LC that one of the front wheels may spin - the xds applies the brake on that side - the excess torque is fed to the other front wheel and could cause it to spin itself. That could naturally lead to a oscillation back and forth between the front wheels. Of course with Haldex I'd imagine it would step in and pass more power to the rear. So by turning the xds to max you are getting the Haldex more involved. Although I'd imagine a true change to the Haldex would be more ideal..
     
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  22. vamos

    vamos Registered User

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    As an extra - after pondering a bit more - xds has nothing to do with Haldex and making the car fwd only - infact turning xds down may also get more power to the rear via the Haldex -
     
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  23. Rob2k68

    Rob2k68 Well-Known Member VCDS Map User

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    No I've not changed the SVR it wasn't available to me on my list of adaptation channels or I probably would have tried it.
     
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  24. Rob2k68

    Rob2k68 Well-Known Member VCDS Map User

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    Can you elaborate ?
     
  25. S3 Turbo

    S3 Turbo Registered User

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    I think both of you are right...

    http://en.volkswagen.com/en/innovat...sary/elektronische_differenzialsperrexds.html

    '
    The XDS electronic differential lock is an extension of the familiar EDL function. However, XDS responds not to loss of traction but to the unloading of the front wheel on the inside of the corner when cornering fast. XDS applies pressure from the ESC hydraulics to the inside wheel to prevent it from spinning. This improves traction and reduces the tendency to understeer. The level of pressure applied ranges from approximately 5 to 15 bar. The impression when driving is similar to that of a limited-slip differential in toned-down form. The precise, one-sided build-up of brake pressure makes cornering even sportier, quicker and more accurate.
    '

    I.e. effectively working as a front limited slip differential, reducing inner wheel spin and giving more power to outer wheel, and thus making the car less understeering when taking turns under acceleration.
     
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  26. vamos

    vamos Registered User

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    Yeah - strikes me that xds is a separate system to Haldex - it's part of the brake / esp sub system - it simply detects a wheel losing traction and applies the brakes on that corner - further if it's like the mclaren idea it's taking in that the car is cornering ( maybe reading steering angle) and applies brakes to the inside wheel to decrease understeer. The Haldex behaviour is a reaction to what this xds is trying to achieve - it may shuffle some of the excess torque to the rear. In fact LC may not be affected at all if it detects no cornering. Then again I maybe talking tosh..;)
     
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  27. gamegenie

    gamegenie Eazy-E CPT OG from the Otherside

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    XDS is the fancy wording for torque vectoring. I remember reading that when I was looking up the Haldex-5 info and found through Audi's press pages that explained the the new Audi TT and Golf-R haldex-5 all wheel drive has rear wheel bias adjustment accessible through Dynamic/Sport mode on Drive Select equipped vehicles.

    A lot of peeps on this forum claim that the press-statements were bogus fluff but I believe it. I don't normally drive in Dynamic because it gives my 2.0T weaker fuel economy, but whenever I do, the car comes alive and is a lot more sportier and game and torquery from the back.
     
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  28. Rob2k68

    Rob2k68 Well-Known Member VCDS Map User

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    So I've been struggling with lots of wheel spin lately and trying a whole load of tyre pressure combos to try and reduce it. Whilst connected to VCDS to close my exhaust valves after having the D/P fitted not sure why but went back into the ABS module and noticed that the XDS differential lock adaptation had somehow became 'not activated' which is very odd - anyhow changed it back to medium and will see how it drives tomorrow.

    May be worth checking this from time to time.
     
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  29. rcnacura

    rcnacura US Spec 8V

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    About to fill up the gas tank, seeing if mileage got better... Will report back, next few days.

    Sent from my SM-N910V using Tapatalk
     
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  30. RS200Z

    RS200Z Registered User

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    Starting Vibration Reduction and Starting Vibration Reduction-Torque Limitation adaptation channels are now available with latest VCDS 16.8.3
     
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  31. Rob2k68

    Rob2k68 Well-Known Member VCDS Map User

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    Great - thanks for the heads up ;o)

    What settings would you recommend ?
     
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  32. rcnacura

    rcnacura US Spec 8V

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    So I just went to Laguna Seca and did one session on normal and then on strong... I didn't really feel that it made much difference.

    Gas mileage stayed about the same on my last fill up too.

    Sent from my SM-N910V using Tapatalk
     
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  34. RS200Z

    RS200Z Registered User

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    I haven't change mine yet to be honest. Am still trying to figure out why my XDS settings changed to Deactivated on it's own after I set it to Medium. I am thinking it could have change due to the Audi Drive Select mode changes. As in different mode calls for different XDS settings.
    Will do further testing and confirm.
     
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  35. Rob2k68

    Rob2k68 Well-Known Member VCDS Map User

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    That's interesting mine did that too think I mentioned that earlier but I put it down to having my ECU flashed from stage 1 to 2 but I've also set it back to medium - good theory could very well be ADS related.
     
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