Engine valves accumulate carbon deposits. Why?
Todays design of the engine comprises means of injecting called “direct injection”, wherein instead of a mixture of fuel and air in pre-combustion chamber is injected at a low pressure of the fuel, it is injected at high pressure directly into the cylinder where it is mixed with air which has already entered. The advantages of direct injection are: better fuel economy, efficiency and productivity.
However, a disadvantage is that the fuel does not pass through intake valves and for this reason they are not cleaned. When you take into account that the inclusion of the system for exhaust gas re-circulation (EGR) is included, which increases the amount of unused fuel, oil and other deposits that enter the intake ports is not surprising that the valves are dirty. A car that has carbon deposits on valves can not display a warning on the dashboard of the vehicle and diagnostic codes that. The first signs are likely to be mild and gradual reduction of dynamics and fuel consumption and smoke may increase.
Clean carbon deposits on valves without dismantling using Carbon cleaning technology, which is quite cheaper alternative compared to dismantling and removal.