The direct injection motor is great at making power and getting great gas mileage. However, there are some extra maintenance steps required for long term engine health and performance. Since fuel is injected directly into the combustion chamber, there is nothing to "clean" the carbon buildup off of the intake valves. This carbon buildup can decrease performance by causing knock or per cylinder timing corrections. Therefore, it must be manually cleaned as needed, or roughly every 30,000 - 50,000 miles by a blasting media cleaning process. Below, you can see a before and after picture that shows how big of a difference this can make!