During main engine performance testing it is noticed that the firing pressure in one cylinder is lower than the average, but cylinder compression pressure and fuel pump delivery rate are normal. Which of the following would most likely be the cause?

Correct Answer: Option A — Late fuel injection

Late fuel injection delays the combustion process, preventing peak pressures from reaching normal design levels while leaving overall compression pressure and fuel rack delivery unaffected. This thermodynamic anomaly results in lower maximum cylinder firing pressure and reduced indicated mean effective pressure.