Ok i was hearing terriblie knock knock knock when i would turn off the car.....bought some injector cleaner and the noise stop ....now when the car is on and off i here knock....knock.....knock....knock...... So know i don't know wat the heck the noise is !help please

 

Are you sure its not just heat expansion? THAT's normal. Is the engine shaking when your shut it down? THAT's a problem