Posted on 5/30/2025
If you’ve driven both gas and diesel vehicles, you’ve probably noticed a few key differences in how they operate. One question that often comes up is: why don’t diesel engines have spark plugs? Since spark plugs are necessary for starting a gasoline engine, it might seem odd that diesel engines don’t use them at all. To understand why, it helps to look at the fundamental differences in how diesel and gasoline engines create combustion and why diesel engines are designed to do things differently from the very start. The Role of Spark Plugs in Gasoline Engines In a gasoline-powered engine, air and fuel are mixed together in the intake system and then drawn into each cylinder during the intake stroke. Once inside, a spark plug ignites this mixture at precisely the right moment, triggering combustion that pushes the piston down and keeps the engine turning. Without that spark, combustion won’t happen. This is why spark plugs are essential ... read more