GDI Engine Cleaning
Gasoline Direct Injection or GDI has seen rapid adoption by the automotive industry over the last several years in lieu of multipoint fuel injection systems due to advantages in fuel efficiency and reduced emission levels.Many of the best new engines have incorporated GDI to see a savings of up to 35% reduced fuel consumption, 20% fewer emissions, and 10% increase in power. However, now that GDI has been in engines for several years, engine builders are seeing issues caused by these systems as well as many facts and fictions surrounding why these problems exist and how to solve them.
The most well-known issue that direct injection has is the injector is located behind the valve instead of in front of the valve so you don’t have that mechanical cleaning of the backside of the intake valve that you would on a multipoint injection. These droplets of oil and small amounts of dust and dirt make their way through the intake ports, which are coated with sticky oil and creates a plaque layer that builds up thicker and thicker and thicker.
Many people think that when your valve is open and the fresh air passes over it, that’s what cools the valve. Your valve really cools when it’s in contact with the seat through heat transfer. The water jackets around the seat pull the BTUs out of the valve. These valves are running hot, so when oil droplets come through the intake port and pass through the cylinder head they’ll stick to the backside of the intake valve.
When carbon builds up on the backside of the valves, it works like an insulator not allowing the valve to cool down properly when it’s in contact with the seat. That causes the valves to get red hot and the valve heads to pop off resulting in a dropped valve down in the cylinder. Even if the valves do not pop off, the build up will continue to increase until the valves can no longer seat correctly causing a drop in cylinder pressure, reduced efficiency, misfires, and poor burn off. The problems worsen exponentially as the buildup increases. The more build up there is, the hotter the valves become and more carbon and oil adhere to the existing build up in an ever worsening cycle.
GDI Maintenance Solutions
Carbon will start accumulating within 5,000 miles. We have seen failure in GDI engines due to this buildup before 60,000 miles. At that point the only solution is to disassemble the top of the engine, remove all the valves, sand blast them clean with a special abrasive material, service all the injectors, then reassemble the engine.
To deal with this build up requires a GDI Induction Service. This uses a certain chemical applied with via a specialized machine that vaporizes the cleaning agent. This vapor is introduced to the vehicle's air intake system while the engine is running. The vapor passes through the air induction chamber, across all surfaces, and over each of the valves until it is ignited in the combustion chamber. This chemical fog breaks down the carbon and debris much as dentist removes plaque from your teeth. A second chemical is added to the fuel tank. This works to treat the remaining parts of the fuel system, remove residual deposits soften by the previous cleaning steps and will continue to clean until the next fuel fill up.
This is the before and after on a 2015 Kia Sorrento with only 57,000 miles. The vehicle was kept in excellent shape but the customer never did any GDI maintenance and the engine ultimately failed.