How does direct injection differ from port injection in metering?

• A. Direct injection meters fuel at high pressure directly into the cylinder, while port injection delivers fuel at lower pressure into the intake port; both use ECU control but different spray strategies.
• B. Direct injection uses mechanical meters; port injection uses no sensors.
• C. Direct injection injects only air, port injection injects fuel.
• D. Direct injection and port injection are identical in spray strategy.

Answer: (D)

Direct injection and port injection differ in where fuel is metered and how it’s sprayed into the engine. In direct injection, fuel is metered and injected at very high pressure directly into the combustion chamber, requiring a high-pressure fuel system and precise timing to place fuel right where combustion occurs. In port injection, fuel is metered at a lower pressure into the intake port (or manifold), where it mixes with incoming air before entering the cylinder, using different spray characteristics and mixing behavior. Both systems are controlled by the engine computer using sensors, but the spray strategy changes because the fuel’s entry point is different. The idea that they are identical in spray strategy isn’t correct because the injection location and pressure create distinct atomization, mixing, and combustion effects.