Which of the conditions listed would cause...

🔍 Key Concepts

• Relationship between injection timing and peak cylinder pressure vs. exhaust temperature • How fuel quantity (rack setting) affects both firing pressure and exhaust temperature together • What happens to cylinder pressure and exhaust temperature during light-load operation and with long exhaust valve opening

💭 Think About

• Ask yourself: which condition would make combustion occur earlier in the stroke, raising the pressure near TDC but giving the gases more time to expand and cool before the exhaust valve opens? • Which option would most likely cause both firing pressure and exhaust temperature to increase together, rather than one high and the other low? • For each choice, think through: does this tend to increase or decrease afterburning in the exhaust stroke, and how would that affect exhaust temperature?

✅ Before You Answer

• For each option, decide whether it tends to make peak firing pressure higher or lower than normal. • For each option, decide whether it tends to make exhaust temperature higher or lower than normal. • Look for the one condition where high pressure in the cylinder happens at the same time as relatively cooler gases leaving through the exhaust (low exhaust temperature).

Which of the conditions listed would cause simultaneous high cylinder firing pressure and low exhaust temperature?

Improper fuel rack positioning.

Lengthy opening of the exhaust valve.

Excessively early injection timing.

Extended light load operation.

🔍 Key Concepts

💭 Think About

✅ Before You Answer