What specification is important to maintain during the ignition timing functional test?

Maintaining OEM specifications during the ignition timing functional test is crucial because these specifications are established by the manufacturer to ensure optimal engine performance and emissions control. OEM (Original Equipment Manufacturer) specifications provide a precise timing range that corresponds to the engine's designed parameters, which helps in achieving efficient combustion and minimizing harmful emissions. Deviating from these specifications can lead to increased emissions and potential engine performance issues, making it essential to adhere to the guidelines set by the manufacturer. This is particularly important in the context of smog checks, where adherence to emissions standards is required for compliance.