Yes. Because the fuel/air mix is directly injected, it does not enter the combustion chamber via the inlet valves and does not clean them. As a result, carbon can accumulate on the inlet valves.
Search the web for 'direct fuel injection history' and two prominent results will often materialise: Leon Levavasseur and the Mercedes-Benz 300 SL. Their prevalence is understandable. Levavasseur is ...
Direct injection, as the name suggests, refers to a type of fuel system which introduces fuel directly into an engine's combustion chambers. This differentiates it from conventional injection systems ...