Which term describes the maximum degrees the PCM will advance the timing?

Which term describes the maximum degrees the PCM will advance the timing?

• A. Rate of timing advance
• B. Total advance
• C. Boost retard
• D. Initial spark timing

Answer: (B)

Ignition timing is controlled by the PCM by advancing the spark before top dead center. The maximum degrees the PCM will advance—the total advance—equals the base timing plus all additional advance the PCM applies as engine speed and conditions require. For example, if the baseline timing is 10 degrees before TDC at idle and the PCM adds 25 more degrees as RPM rises, the total advance is 35 degrees. This total value is what determines the most the spark can be advanced under running conditions, within the safety limits set by the engine’s maps and knock protection. The rate at which timing changes with RPM is a separate idea (how quickly timing advances), while initial spark timing is simply the baseline before any dynamic advance, and boost retard refers to dialing timing back under boost.

Ignition timing is controlled by the PCM by advancing the spark before top dead center. The maximum degrees the PCM will advance—the total advance—equals the base timing plus all additional advance the PCM applies as engine speed and conditions require. For example, if the baseline timing is 10 degrees before TDC at idle and the PCM adds 25 more degrees as RPM rises, the total advance is 35 degrees. This total value is what determines the most the spark can be advanced under running conditions, within the safety limits set by the engine’s maps and knock protection. The rate at which timing changes with RPM is a separate idea (how quickly timing advances), while initial spark timing is simply the baseline before any dynamic advance, and boost retard refers to dialing timing back under boost.