when you turn the key off alot of stuff should stop getting power. the computer should go from an ative mode to a standby mode, the injectors should go open, and the coil should stop recieving voltage from the coil. it is not like an old carbed car where if you were to leave power at the coil it would just keep on running. i bet it is your switch, there is alot of things that need to stay on. does your bat go down if you leave it parked for a long period of time?