Which technician is correct regarding testing spark advance?

Testing spark advance is a crucial aspect of engine performance as it involves understanding how the ignition timing affects engine efficiency and power output. Technician B is correct because one key point in testing spark advance involves using a timing light to check the ignition timing while the engine is running. This method allows for precise measurements of when the spark plug fires relative to the position of the crankshaft. It's essential to ensure that the ignition timing aligns with the manufacturer-specified settings for optimal engine performance.

Additionally, testing can reveal whether the spark advance varies with engine conditions, such as RPM and load, which can indicate proper functioning of the ignition advance mechanisms, such as the vacuum advance or electronic control units. A technician's ability to correctly interpret the readings from the timing light is vital for diagnosing ignition system problems effectively.

Understanding how to recognize correct and abnormal spark advance helps in tuning the engine properly, which can lead to improved fuel efficiency and reduced emissions. This makes Technician B's assertion relevant and critical for assessing engine performance during diagnostics.