Question 34Motor Plants - QMED

The correct answer is B) oil in the air charge. Pre-ignition in a diesel engine can be caused by oil in the air charge. The presence of oil in the air can lead to hot spots that can cause the fuel to ignite prematurely, before the normal ignition timing. This premature ignition is known as pre-ignition and can result in engine damage. The other options are incorrect because: A) Excessively late fuel injection would not directly cause pre-ignition. C) Water in the fuel would not lead to pre-ignition, but could cause other issues like poor combustion. D) Injection continuing after the fuel charge is ignited is a normal part of the diesel engine cycle and does not cause pre-ignition.