Which of the following can be corrected by tuning the engine?

Tuning an engine primarily involves adjustments that can optimize its performance, efficiency, and emissions. One of the most significant results of a proper tune is the improvement in fuel efficiency. When an engine is tuned, parameters such as air-fuel mixture, ignition timing, and valve timing can be recalibrated to ensure that the engine runs more efficiently, leading to better combustion and, consequently, higher fuel efficiency.

This improvement happens because a well-tuned engine operates closer to the ideal combustion conditions, which minimizes fuel wastage and enhances power output from the available fuel. Consequently, if a vehicle is experiencing poor fuel efficiency, tuning can help restore it to optimal levels by ensuring that the engine components are working harmoniously.

In contrast, while increased noise levels, excessive exhaust odor, and engine overheating can signal underlying issues or malfunctions that require different interventions—such as mechanical repairs or component replacements—these issues are not typically resolved through tuning alone. Therefore, tuning is a vital corrective action for improving fuel efficiency.