What is a "timing light" used for?

A timing light is a diagnostic tool used specifically to check the ignition timing of an engine. This tool stroboscopically illuminates the timing marks on the engine's crankshaft and timing cover, allowing a technician to see if the timing is set correctly. Proper ignition timing is crucial for optimal engine performance, as it ensures that the spark plug fires at the right moment in the compression cycle. If the timing is off, it can lead to decreased performance, increased fuel consumption, and possibly engine damage.

In contrast, measuring fuel efficiency primarily involves different diagnostic tools and methods focused on evaluating the amount of fuel consumed relative to the distance traveled. Analyzing exhaust emissions would utilize sensors and equipment designed specifically to measure pollutants and emissions released from the engine. Adjusting tire alignment, on the other hand, involves equipment that assesses and adjusts the angles of the wheels for optimal vehicle handling, which does not pertain to engine timing at all. Thus, the specific purpose of a timing light as a tool is correctly identified as checking the ignition timing of an engine.