Hi folks, been reading a lot about carbon build up on direct injection engines lately (GDI) and as I've just bought a car with one of these, have been doing a bit of research. This guy on YouTube seems to do a pretty good job of explaining the problem, see linky:
https://youtu.be/_1CK6aBFSXA?si=MMaMQ9vkpbwzlUvUInterestingly, he mentions at the end of the video, (at 14min 24sec) that this is far more common with larger engines and slower revving engines, which ties in with what I've seen, eg: lots of US based owners with 2.5 - 4 litre engines having issues.
Luckily mine is a smaller engine, so hopefully will not have too many issues.
Just thought the info might be useful to some people. Cheers