Proper mixture control and better economy in the operation of a fuel injected engine can be achieved best by use of?

The utilization of an exhaust gas temperature (EGT) indicator is crucial for achieving proper mixture control and optimizing the fuel economy of a fuel-injected engine. EGT provides real-time feedback on the combustion efficiency and allows the pilot to make informed adjustments to the fuel mixture. By monitoring the temperature of the exhaust gases, the pilot can lean or enrich the mixture to maintain the optimal fuel-to-air ratio, ensuring efficient combustion.

When the mixture is lean, the exhaust temperature rises, indicating that the engine is running efficiently. Conversely, if the mixture is too rich, the exhaust temperature will drop, signaling that there is too much fuel compared to the air being used for combustion. Thus, using an EGT indicator enables more precise tuning of the engine's mixture settings, leading to better performance and fuel economy.

Other options may play a role in engine operation but do not provide the same direct insight into mixture control. For example, a fuel flow gauge can help monitor fuel consumption but does not give information about the combustion efficiency in real-time. Manifold pressure and RPM settings are important for adjusting power but do not convey the information needed to optimize the mixture for fuel efficiency. A throttle position indicator is also less relevant as it indicates only the position of the throttle lever