Gt4
GT4 is a game printed on DVD9
Assuming that we are taking about the "ahem cheap" games.
This is available in
GT4 NTSC/J (Japanese version)
GT4 NTSC/J (Chinese version)
GT4 PAL (English version)
GT4 NTSC/UC (English version did not worked)
In order for this game to run, everything have to be in tip top condition.
Console; condition of the laser lense.
"ahem cheap" games
The disk has to be in good condition, as these are "ahem cheap" games, there is just no quality quality control.
Mod Chip has to support DVD 9 (most of the mod chip, 2 years ago already support DVD 9)
From these messages, a calculated guess is that most of your console is not in ultimum condition. This point to the laser.
Your options are,
1) If your console is running well, especially with DVD9 movies. Buy an original GT4. Think it is 300plus.
2) If your console is running well, especially with DVD9 movies. Send your console for repair, tweaking (tunning) of the laser. But be warn that, this might break your console as it comsume lots of wear on the laser lense, especially playing DVD 9 games.
3) Change the laser lense. Costly, think it could cost from 240 to 480.
4) Buy a brand new bear set unit.
Why can DVD 9 movies work and not GT4.
The "ahem cheap" movies, unlike games, had the regional code lock ripped off in the software. Movies run sequencialy. Games is different as the data are packed randomly and you move from place to place (depending on where you navigate in the game). You can listen to the movement of the laser lense when it tracks & focus on the disk eeeeeeh, subbbbb sound.
My personal recommedation is if you must play GT4, then go for option 4. Use the new console only to play games that do not run on the old console. Use the old console for games until it total died down, discard. This shall save you more $ and less headache. There are certain life spent on each and every equipment, just use the PS2 for games. DVD are very cheap to buy.
The solution that I had taken is that, I saved all these $ on repairs and got a Kotal-X made by abang Bill. I am paying Fonza Motorsport. It is much better that GT4 and less costly and less headache in the long run.
** this is just my personal opinion, just sharing