🔍 Key Concepts

• Fuel injection nozzle problems and how they affect combustion • Relationship between firing pressure and quality of combustion in a diesel cylinder • How exhaust temperature changes when fuel burns too early, too late, or too slowly

💭 Think About

• Think about what happens inside the cylinder if extra fuel is entering continuously instead of as a clean, sharp spray at the correct moment. • If combustion is poor and incomplete, would you expect the gas pressure at peak firing to be higher or lower than normal? • If burning continues later into the power stroke and possibly even into the exhaust, what would that do to the exhaust gas temperature?

✅ Before You Answer

• Compare which options show high vs. low firing pressure and decide what poor, leaking injection would most likely cause. • Check which answer choices pair high exhaust temperature with low firing pressure, and which do the opposite. • Remember that compression pressure is mostly about the condition of the piston/rings/valves, not directly about nozzle leakage—use that to rule out distractors.