If you’ve been following the development of direct injection engines, you know there’s great performance and economy gains, and you’ve probably seen that maintenance of those engines is a little more unique.
The direct injection (DI) engine, by virtue of it’s design, does absolutely nothing to keep the intake valves clean. A port injection (read: ‘normal’) engine sprays it’s fuel above the intake valve, which aids in keeping it clean. The DI engine injects, surprise, directly into the cylinder, and when you couple this with the exhaust gas re-circulation (EGR) systems that are coming back into play, and you’ve got a recipe for gunk.
We’ve added the capability of cleaning those valves off and restoring lost drivability, power and economy. Those deposits rob you of airflow, and in a modern engine, airflow is everything.
We use a system that sprays crushed walnut shell into the intake port, with the valves closed, and a special vacuum system to keep it all contained. A spray wand allows us to accurately clean things, and by using crushed walnut shell, we avoid any contamination and there’s no risk to the soft aluminum cylinder head or the intake valves themselves.
We’re recommending this service for any medium to high mile 2015+ WRX before dyno tuning, and especially if we’re adding an Air/Oil Separator (AOS) and updating the Tumble Generator Valves (TGV) or Exhaust Gas Re-circulation (EGR) systems.
This service isn’t limited to the WRX, it applies to ALL direct injection engines, so at the time of this post, for Subaru, that’s the 2015+ Subaru WRX, 2012+ BRZ, 2017+ Impreza, and the 2014+ Forester XT.
A 10k mile FA20DIT before cleaning…
… and after cleaning!