Direct fuel injection, which sprays fuel directly into the cylinder to mix with incoming air. (autoweek.com)
Also things such as incoming air temperature, engine core temperature (coolant), and, valve size are all factors in maintaining cylinder pressure. (mechanics.stackexchange.com)
The role of a cabin air filter is to remove dust, pollen, mold, and other pollutants from incoming air before it reaches you. (citytoyota.com)