I can remember cleaning cylinder chambers of hard carbon deposits the kind that’s like coaking the rock hard shit you need a Jack hammer on. Sounds like wife’s tail but works, get ATF fluid slow drizzle pour down the throat while keeping it running it wants to stall also make shit load of steam and cylinder pressure go ballistic if not controlled it can expand the goods and start stuffing rings and piston skirt. It does work. Once done if you had open headers or zombies you would have all the black carbon shit everywhere. And if it was pinging and detonated if done right, would be gone. Not for your average bozo to try or could ruin the engine.