What occurs at or near the end of compression stroke and just before the power stroke?

• A. Fuel injection
• B. The intake stroke of the engine
• C. The exhaust stroke
• D. Crankcase ventilation

Answer: (A)

Fuel injection timing is the key here: in a diesel engine, fuel is injected at or near the end of the compression stroke when the air in the cylinder is highly compressed and hot. This timing allows the fuel to ignite almost immediately upon contact with the hot compressed air, initiating the power stroke as combustion drives the piston downward. If injection happened too early or too late, ignition would be mishandled and engine efficiency and smoothness would suffer. The intake and exhaust strokes occur at other parts of the cycle, and crankcase ventilation is a separate system, not tied to when the power stroke begins.