Diesel engine does not have an ignition coil mechanism. Diesel engine is also known as compression ignition engine. The heat of compression is used to burn fuel that has been injected into the combustion chamber.
Contrary to popular belief, lemon is not a hazard for an inflamed larynx. Lemon is known to help reverse voice loss. If you are suffering from a sudden loss of voice; all that you would need to do is to mix a few drops of lemon juice and honey in a glass of lukewarm water. Alternatively, one could even dissolve a few drops of lemon juice in a glass of warm water and add a pinch of salt.
The straw technique may be the answer to your vanishing voice. This method involves blowing or humming through a straw, like you did into your milkshake as a kid. It's an effective way to invigorate tired vocal chords because it works the muscles that give your voice its regular projection abilities.