* Spark Plugs: They don't directly contribute to power, but they are crucial for igniting the fuel-air mixture, which is the very foundation of the engine's operation.
* Camshaft: The camshaft itself doesn't create power, but it controls the valves that let air in and exhaust out. Without the camshaft, the engine wouldn't be able to cycle air and fuel, rendering it useless.
* Timing Belt/Chain: While it doesn't generate power, it ensures the crankshaft and camshaft rotate in perfect synchronization. Without it, the engine would be completely out of sync and unable to function.
So, depending on how you define "no purpose", there are several components that are essential but don't directly contribute to the engine's power output.
