You must perform the steps in this video if you would like to avoid carbon deposits on intake valves, piston crowns, catalytic converter and always follow manufacturer's instructions before performing anything seen in the video.
Stp pro series intake valve cleaner is a great intake valve cleaner to use. How to clean carbon buildup with Liqui moly valve clean or crc GDI Intake Valve Cleaner. How to stop carbon buildup on a GDI engine? You can't completely stop it from building up but you can make it significantly easier to remove.

свернуть