🔍 Key Concepts

• relationship between injection pressure and timing in diesel engines • how spring tension and opening pressure affect when the injector starts spraying • effects of injection timing on combustion and exhaust temperature

💭 Think About

• If the valve opens at a lower pressure, will fuel start to flow earlier or later in the compression stroke? • How would earlier vs later fuel injection affect how completely the fuel burns and the resulting exhaust temperature? • Which of the options is a direct, primary result of the change in opening pressure, rather than a secondary effect?

✅ Before You Answer

• Be clear whether lower opening pressure makes the injector start injecting sooner or later relative to piston position. • Think about whether high exhaust temperature is a cause or an effect of improper injection timing. • Verify which choice describes the immediate mechanical consequence of changing the opening pressure, not the longer-term engine symptom.