If you have been following discussions concerning direct injected engines and the formation of carbon deposits, you are right to be concerned. Many of the late model Subaru engines are direct injected and routine cleaning is recommended. If you decide to have this service preformed at a shop expect to pay 175.00 to 200.00. If the problem is real bad the price can sky rocket. Do it your self kits are available (SeaFoam) but in the case of Subaru Turbo motors not possible due to the location of the intercooler. There is a solution for the do it yourselfer. Locate the MAP sensor located on top of the intake Manifold. It is held in place by a single 10 mm screw. Carefully remove the sensor leaving it connected. What you now have is a nice 7/16 hole direct into the intake manifold. Purchase a Rubber cork size 00. which will fit the hole nicely. Purchase a can of SeaFoam spray with the long red tube attachment . Drill the cork and insert the tube thru the hole. Place the cork into the manifold hole and there you have it. Start the engine and have an assistant hold the RPMs around 2000. Hook the can to the tube and start cleaning inacordance with SeaFoams instructions. Things to keep in mind. Prevention is key . Do not wait until carbon becomes a issue. Better to clean early in the deposit cycle before the carbon sets up. Have used this method on several club members cars with good results and have experienced no problems. Hope this info helps.
Yeah, keeping the intake valves clean on a GDI engine is a problem, but it looks like you’ve come up with a pretty slick solution. I’ll have too check to see if my wife’s Soul and my Tiguan are still using MAP sensors.
Ford has come up with an interesting solution to this problem on their 2.7 liter
They run port injection at an idle to clean the valves & GDI above an idle for the better performance.
believe it or not Subaru also has a solution but as far as I know its only available on their new 2 wheel drive sports car. Subaru it seems is working with Toyota using the same concept you just mentioned.