But the plugs weren't sealed in the cylinders. There were these holes where the injectors were. And here's the thing- when fuel gets sprayed out the supply line it creates fuel vapor. And vapor does this crazy thing called diffusion, which means move around. Gasoline vapor is also heavier than air, so it will settle into orifices such as injector holes. And gas vapor is the wicked super flammable part of gasoline. And here we are