Ignition timing is determined by the crankshaft position.

• A. Crankshaft
• B. Camshaft
• C. Piston
• D. Flywheel

Answer: (A)

Ignition timing is set by the crankshaft position because the spark must occur at a precise crank-angle as each piston moves, ensuring the air–fuel mixture ignites at the right moment for efficient combustion. The engine uses a crankshaft position sensor to provide this angular reference to the control unit, so spark timing is tied to where the crankshaft is in its rotation.

The camshaft controls valve timing, not when the spark fires. While piston position is related to crank angle, the system uses the crank position as the standard reference for ignition. The flywheel plays a role in inertia and starting, not in determining when to spark.

So the crankshaft position is the best and most direct reference for ignition timing.