I’m wondering if you could recommend me something. I have a 2010 Prius with 186k on it. Yesterday, I took off the intake manifold and egr tube to clean out the carbon buildup. I wanted to. Lean the egr valve and cooler as well, but couldn’t get access to it. The carbon buildup was awful. Inside the engine I could see a lot of thick carbon buildup that I couldn’t get to. I’m wondering if there’s anything I can spray through my throttle body or put in my oil that can clean this carbon out, primarily through my egr system.
No. There's no magic spray. That stuff is removed with a process called walnut blasting. The cost isn't all that bad .... around $200.
https://www.rivercitymotors.ca/walnut-blasting/
Otherwise, you can get bore brushes (the brass ones would work well) that mount on your drill, and a few cans of brake cleaner, and go to town.
