Grip bug thread

Discussion in 'Gran Turismo Sport' started by GT_Alex74, Jan 9, 2018.

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  1. GT_Alex74

    GT_Alex74

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    This thread is there to gather all the informations forum members found on a bug which can potentially have a huge impact on the game in the same place and in an organized way, in a hope Polyphony Digital can use this to identify and solve this issue in the best possible conditions. I will ask you to refrain from posting rants about the game or devs as that won't help in any manner and I'd like this topic to remain as clean as possible to allow further discussion if needed. I myself didn't do much except watching and asking a few questions, credits goes to those who did the research and RA1784 for taking his time to do all the tests.



    - What is this bug ?

    Basically, it is a bug which seem to change the physics of the game, allowing people who benefit from this lap times around 3 seconds or more faster than what they would achieve in regular conditions. It allows to brake much later and accelerate sooner than normal, while giving superior stability, as if the car was on rails.

    - How was it discovered ?

    Courtesy of some fellow GT Planet members and regular top 10 scorers for years. These guys noticed new people putting up abnormally fast laps above regular world records, so they started watching closely the replays and noticed something was wrong. It was publicly called out by Spurgy on GT Planet (link), and after some exchanges on the bug report thread, RA1784 invited people who showed interest in the investigation into a PSN chat (part 1/part 2/part 3/part 4) to clear things out. RA1784 was asked to perform various tests until we found where it came from.

    - What we know :

    * it is directly related with the game progress save file (deleting it and not loading it back removes the glitch)
    * it is not related to the game settings save file (deleting it doesn't change anything)
    * uninstalling and reinstalling GT Sport doesn't remove the glitch
    * it is not related to console hardware
    * it is not related to the temporary files cache
    * it works even on the softest tyre compound
    * it is not caused by a set of driving assists
    * it is not linked with liveries (including custom wheels) or gifted cars
    * it is not caused by internet connexion speed
    * it works both online (lobbies and sport mode) and offline with all cars
    * it might be connected to another bug (driving preferences such as ABS, FFB and transmission always resetting, as well as the view) - If you experience this bug, please contact me by sending a PM here.
    * at least 4 different users were spotted driving with this glitch thanks to suspect lap times in the top 10 leaderboard replays, but there might be naturally slower drivers outside of top 10 infected with this bug as well
    * it effects lap times by around 3 or 4 seconds per lap
    * it is not connected to the debug menu glitch

    - What we don't know :

    * what triggers the bug
    * what exactly it does to the physics
    * if using a T100 wheel had any effect (most probably not but that wasn't thoroughly tested)
    * if an update can corrupt a savefile
    * how many people exactly are touched by this



    As regular players, I think we did pretty much everything we could do with the tools we have access to and the much appreciated cooperation of RA1784. It is now in the hands of Sony and Polyphony Digital to identify precisely what's wrong in the saves, figure out the technical details and work to solve this issue.

    @Spurgy 777 You may want to put your videos and other stuff directly in this thread, I'll edit this post to add them here if necessary.
    @RA1784 If you could upload your save file backup there as well, that would be ideal (EDIT : we discussed this and thought it would be better to keep it offline until someone from PD asks for it to prevent any hacking possibility)
    @MINKIHL @zzz_pt @Shottah072 @Rick23 GT @kubstar @nissman @Tidgney @Iceman If you have anything to add in there, don't be afraid to do so as well.
    @Jordan if you have any way of contacting Kaz or someone at Polyphony Digital directly, the community would appreciate if you pointed them to this thread.

    If I missed something or wrote something wrong in there, please correct me, but I think for now that's pretty much all what has been said and done.

    EDIT : MINKIHL sent me the pictures comparing his braking points with RA1784's braking points in better quality than what you can see in the PSN chat screenshot, so here they are (and RW stands for soft tyres in German, they're not wet ones). From his own words : "Its the frame where we both hit first time full brake."

    [​IMG]
    [​IMG]

    Also, here's a post from Spurgy with a few videos showing laps done with the bug :


     
    Last edited: Jan 11, 2018
  2. Jump_Ace

    Jump_Ace Staff Emeritus

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    Thank you all for taking the time to figure this all out :tup:


    Jerome
     
  3. zzz_pt

    zzz_pt Premium

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    Looks fairly detailed IMO. Great job Alex.

    Would just add here that the settings @RA1784 mentioned were: ABS, transmission (manual goes back to auto) and FFB settings.
     
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  4. Nando deBem

    Nando deBem

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    This seems pretty big.
    Did anyone notice if it affects grip levels during daily races and FIA sessions?
     
  5. zzz_pt

    zzz_pt Premium

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    It affects lobbies so I'd guess it also affects sport mode.
     
  6. Voodoovaj

    Voodoovaj

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    I KNEW IT!!! Is it connected to the debug menu bug? Are the player who have the debug menu also experiencing the extra grip? Is there some other common thread like Beta test users or some other special group?
     
  7. Shottah072

    Shottah072

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    Apparantly it is not.

    Great report @GT_Alex74 not much to add really. Hope PD can figure it out. And thanks to @RA1784 for helping and trying to understand what is wrong.
     
    Last edited: Jan 9, 2018
  8. Nando deBem

    Nando deBem

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    I remember checking some strange laps in the top 10... and then trying to mimic them and not being able to come near the same time. I thought it was just my own lack of skill though. Should have payed more attention.
     
  9. GT_Alex74

    GT_Alex74

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    RA1784 started to play end of october. Also he didn't have the debug menu thing, I added that to the check list in OP.

    It looks like it does indeed.
     
  10. iFerrari

    iFerrari

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    Keep in mind that it's clearly visible whoever has this bug usually it's through braking zones, when RA had it he could brake 40 meters later than normal through corners
     
  11. CJ1045

    CJ1045

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    Top analysis - just hope PD sees, analyses and acts.

    CJ
     
  12. Stotty

    Stotty Premium

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    Great find guys!!

    Also...

    Waits for half the people playing the game to suddenly think the reason they aren’t the fastest in the world is because everyon else is exploiting this bug ;)
     
  13. Nando deBem

    Nando deBem

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    Yep... I remember that. I tried changing brake balance, but I would never get the same braking power. And the replay I remember used some strange low gears through some corners.
     
  14. Voodoovaj

    Voodoovaj

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    He mentions that he has the CD version of the game. Has that been ruled out as a culprit? For instance, are all folks with the bug CD users?

    CD builds have to go out much earlier than download versions and maybe an early build didn't get a proper patch.
     
  15. RA1784

    RA1784

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    I used the same CD on the same PS4 with my 2nd account with no bug. So probably yes CD is ruled out
     
  16. zzz_pt

    zzz_pt Premium

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    Nothing to do with CD. RA made another account, playing with the same CD, and had no issue. The problem was with the game progress save file.
     
  17. Seikenfreak

    Seikenfreak Premium

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    Hmm interesting. Not sure if you've done it already but it'd be helpful to see a direct side by side comparison of a single corner for example to demonstrate how this actually looks.

    Because I'm watching a replay over here on the US boards from today, and it definitely looks like a computer is driving it based on the telemetry. The person takes a horrible line on some corners and overall it looks like a bad lap, yet is somehow a second faster than some of the fastest people we have in our region. But it doesn't necessarily look like the braking distance itself is an issue to me. It's like, the whole thing is poor driving in general. Like I said, looking at the telemetry/HUD while they run, the inputs seem inhuman and digital. And CSA is flickering on while driving in a straight line? Weird stuff.

    I'll say I don't think I have the bug because my braking distances suck :lol:
     
    Last edited: Jan 9, 2018
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  18. phil_75

    phil_75

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    I have disc and not affected.
     
  19. iFerrari

    iFerrari

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    @MINKIHL should have a clip if I'm not mistaken, CSA has nothing to do with the bug RA was driving without it.
     
  20. Voodoovaj

    Voodoovaj

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    I was looking for an affect the other way, not that all CD users are affected, but that those affected are all CD users. But that's been ruled out.
     
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  21. kubstar

    kubstar

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    great work Alex! nothing more to add atm.:cheers:
     
  22. FPV MIC

    FPV MIC

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    Back in GT 6 days @kilesa4568 had some success getting through to PD about the SRF bug in QM's. He reported it on the Playstation Europe forums with a link to the thread with the evidence here on GTP, and MastrGT from the forum (he apparently has a line to PD somehow) got the info to them. It was never resolved but this may be a way of getting the info to PD.

    @kilesa4568 , @Tassie_tiger : Could either of you help with this? (I'm not good with this kinka stuff:O)
     
  23. Sean Renon

    Sean Renon

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    That would explain one of the top 10 times I was watching where honestly it looked like he had no idea what he was doing but his brake points were drastically later than I could achieve and the power went down with no loss.
    Can't remember the name.
     
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  24. JacksHerer

    JacksHerer

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    Now that more people are going to be aware this issue exists, we can all look out for it and save replays to analyse. And share if there is something worth seeing.

    I have had occasions where I've been amazed how someone could stop their car during a sport race, but it wasn't a competent player and was in DR:B so if they had this bug they won't have known, they must have wondered why everyone else was so bad on the brakes but so good everywhere else.

    Hats off to you guys for identifying it and especially thanks to the guy with it for his openness and honesty to discuss it.

    Edit: I just read page 4, I do wonder if that PS3 wheel is related, if the game has hidden abilities to help controllers compete against wheels, and the initial game Config thought he was on a controller and giving him hidden benefits which weren't reset when he switched to g29.

    Is there anyone out there with T100 to help eliminate.

    Did the guy say if his times improved after switching to the g29 from t100, or were quick even before changing wheel.?
     
    Last edited: Jan 9, 2018
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  25. Jump_Ace

    Jump_Ace Staff Emeritus

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    So much this :lol:


    Jerome
     
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  26. dabz343

    dabz343

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    Interesting to say the least. Great find and ongoing analysis. I thank all those involved to alert PD, especially RA1784 for being transparent and a willing lab rat. Even if this means losing all of his progress.

    Now how will PD respond up to shore up the integrity of GTS?
     
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  27. Tidgney

    Tidgney Premium

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    Great job everyone :)
     
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  28. Corsa

    Corsa Premium

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    That's why I'm so slow, I knew it wasn't me!
    Definitely going to be keeping an eye out for this and saving/uploading replays if I come across it.
     
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  29. andryush

    andryush

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    I remember, when I was playing closed beta back in mid 2017. Back then, game had some input lag issues related to server performance. Some of you may also remember case of different physics online vs offline in GT5 and GT6, and that bug I have experienced in GTS Closed Beta was something very similar to it in my opinion.

    So it was like one day cars felt heavy and unresponsive, and other day driving was super smooth. Feeling change was colliding with server side updates by PD, and connection latency change - for example standard ping for me was ~80ms, then PD updated servers and then suddenly I had 20ms ping but driving felt worse, cars were unresponsive and felt heavier. (better ping should result in more responsive online experience). Then ping changed again, back to 80ms, but overall lagged heaviness in steering remained unchanged.

    I know you mentioned that this bug isn't related to connection speed, but PING isn't the same. And basing on my experience with beta, handling change wasn't related directly to ping or internet connection speed. Rather that ping change was one of the symptoms of server update which caused major feeling change. Maybe @RA1784 is experiencing something similar? Better console - server connection? Does GTS have this PING indicator in retail version?

    Also less lag would explain why these guys from top of the leaderboards have very late braking points - they simply have better controller response.
     
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  30. JacksHerer

    JacksHerer

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    He didn't have the problem on his sub account, so network can be eliminated.
     
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