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 ...

Modern engines are cleaner and more efficient than the ones you grew up with, yet many drivers are discovering a new headache ...

How does direct fuel injection work? Instead of having injectors in a throttle body, or in the intake manifold, a direct injection system makes use of an injector that fires into the combustion ...