Circumventing GT4's Save System

[TeaKanji]

Hello all, many of you are probably aware of how GT4's save system works. Your save is tied to one memory card only, and if the game tries to save and it detects a 'different' GT4 save, it will prompt you before saving over it. If you choose to overwrite the save, it will delete all the cars in your garage except the one you were currently driving. You can't change cars either before this happens, as the game tries to save as you get into a different car.

I wanted to know if there's a way to circumvent this, using cheat codes or modding. From what I can tell, there are two main options:

• prevent the game from checking to see if the current game state matches the save file before saving
• prevent the game from deleting your garage when overwriting a different save or creating a new save

I assume there must be some flag or checksum that the game checks for before saving. I'm not knowledgeable about how PS2 save files are structured, but I'd be surprised if GT4 was doing expensive I/O for every autosave. If there was a way to override that check and make it return true every time, surely that would do the trick.

As for option 2, I assume the garage is stored somewhere in local memory (it's how those 'full garage' cheat codes would have to work). I'm guessing that, when the game creates a new save, it wipes the garage from memory and saves with only the one car that you're currently in. If there was a way to prevent this wipe from happening, I guess that would work too.

There are a lot of uncertainties in this post, and I'm sure I'll be corrected on a few things. As for why I'm curious about this, I was doing some car tuning comparisons with save states, then I went back to the menu with an older save state and I was prompted to overwrite. Didn't realize that the game would wipe my garage so I didn't make a backup of my save file, and now I'm stuck with save states that I can't save with. I wasn't the only person who fell for this, and I doubt I'll be the last either. Yes, backing up is a solution, but it shouldn't have gotten to that point to begin with. Thanks for your time and knowledge.

 

[666666]

I used to mess about with GT4 saves but I made sure I had more than one memory card think I had 3 . I had one card labelled master and used then others to write over.
Think that’s the best way to solve the problem

 

[60fpshacks]

I would guess that all cars except the current one you are in (in-game) are compressed to the memory card.

 

[tankuroded]

Well... coincidentally...

 

[60fpshacks]

@Nenkai

What happened? Why was it taken down?

https://github.com/Nenkai/PDTools.SaveFile/GT4

Edit: Nevermind. I see it is here: https://github.com/Nenkai/PDTools/tree/master/PDTools.SaveFile/GT4

Could you compile it and post a link for us?

And speaking of its layers, I am pretty sure that was done because the GT3 garage editor revealed a hidden Porsche and a Lamborghini (I know, the JGTC was supposed to be only in the Japanese version right?) to exist.

 

[Nenkai]

It's still a work in progress.

Allows full hybridding at the moment, but I want to work on event unlocks among other progression based things.

It'll be properly released once that is done.

 

[60fpshacks]

It's still a work in progress.

Allows full hybridding at the moment, but I want to work on event unlocks among other progression based things.

It'll be properly released once that is done.

Sounds like this one will be better than the old (but still good) GT3 garage editor.

One thing I noticed while searching for values years ago using pcsx2 and Cheat Engine was if you put a race car engine in a car you must also install the racing exhaust as well or it will freeze up when trying to race.

Though, you have probably already found more than most others know about it. And since this is about GT4, I was wondering if you and maybe @TheAdmiester were planning on releasing any mods for this game like what was done with GT6's engine sounds.

Also, yours and others' work on things like this is much appreciated. Thank you much.

 

[TheAdmiester]

Sounds like this one will be better than the old (but still good) GT3 garage editor.

One thing I noticed while searching for values years ago using pcsx2 and Cheat Engine was if you put a race car engine in a car you must also install the racing exhaust as well or it will freeze up when trying to race.

Though, you have probably already found more than most others know about it. And since this is about GT4, I was wondering if you and maybe @TheAdmiester were planning on releasing any mods for this game like what was done with GT6's engine sounds.

Also, yours and others' work on things like this is much appreciated. Thank you much.

The potential is there, I don't have any solid ideas for tweaks myself yet though. No plans but never say never.

 

[Nenkai]

https://github.com/Nenkai/GT4SaveEditor/releases/tag/0.1.2

May break, needs testing. Should have plenty to do with for now.

 

[60fpshacks]

Very interesting:
1. Narration (I had no idea this could be disabled.)
2 Enable AC3. (I wonder if this has something to do with the PSP.)

I figured that you would find more in the save data than was previously known and maybe unused. It seems I was right about the other non-current car data being compressed back to the memory card. I guessed this because when hacking and making GameShark codes for this game I could not find known values for the other cars.

I was wondering, when you update it again if you could add support for .psu save container support and an option to save the decrypted save data files.

Very much thanks to you for this great tool.

 

[60fpshacks]

@Nenkai

"Important Notes!
-The garage file cannot be decrypted as it depends on shuffled crypto which might differ between hardware."

Importing the save from PS2 OPL VMC to pcsx2 memory cards cases no issues, loads, and works fine.