Technician A says that glow plugs assist in starting a diesel engine and are turned off immediately after the engine starts. Technician B claims they are turned off once a flame is detected. Which technician is correct?

Glow plugs play a critical role in starting diesel engines, as they help raise the temperature of the air in the combustion chamber to facilitate ignition during cold starts. However, the assertion that glow plugs are turned off immediately after starting the engine is too simplistic.

Technician A's statement suggests that glow plugs are deactivated right after the engine starts, but this does not encompass the full operation of glow plugs, which can remain active for a short period even after the engine has started, particularly in colder conditions. This is done to assist in smoothing engine operation and ensuring stable combustion.

On the other hand, Technician B's claim that glow plugs are deactivated once a flame is detected also lacks accuracy, as modern diesel engines may not directly control the glow plugs based solely on flame detection. Instead, they are typically controlled by the engine management system, which considers various factors, including temperature and engine speed.

Thus, neither technician presents a complete or accurate description of the operation of glow plugs, leading to the conclusion that the correct response is that neither Technician A nor Technician B is correct.