In retrospect, a bit of fuel does move over the valves but it's in the form of oil/fuel vapor, recycled from the emissions system which initially causes the problem. However, there is no steady stream of injected fuel that washes over the intake valves, as in a port injected engine.
Most fuel additives will not help with the
intake valves. However, such treatments will keep the injectors and exhaust valves clean. A direct reduction in blowby, (oli/fuel/water vapor) via a CC and a sharp reduction in stop and go traffic and short trips will do the most good. Along with this, hard acceleration to speed limits on at regular intervals, will help reduce the carbon deposits.
There are some engine treatments like;
Cerma, which will combine a nano molecular barrier to metal and form a barrier coating on intake valves and other internal engine parts. This will aid in reducing carbon from sticking to the intake valves. A BG FI/engine treatment every 15K miles, will further aid in the removal of carbon on intake valves as well.
It's the best we have to combat GDI issues. Besides, I enjoy a good romp on the throttle to blow out the cobwebs.
