Which term describes the PCM's adjustments during start-up and open loop?

Which term describes the PCM's adjustments during start-up and open loop?

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

Answer: (D)

Initial spark timing is the base ignition setting the PCM uses before any feedback or dynamic adjustments. In start-up (cranking) and in open-loop operation, there’s no O2 feedback to tune timing, so the ECU relies on a pre-programmed map that sets this base timing. That base value determines how much spark advance is available at low RPM and during starting, and the system can add more advance later as conditions allow, but the starting point remains the initial timing. The other terms describe how timing changes once the engine is running (rate of timing advance), the total amount of advance after all adjustments, or a condition-specific retard such as under boost, which isn’t about the baseline used during start-up or open-loop.

Initial spark timing is the base ignition setting the PCM uses before any feedback or dynamic adjustments. In start-up (cranking) and in open-loop operation, there’s no O2 feedback to tune timing, so the ECU relies on a pre-programmed map that sets this base timing. That base value determines how much spark advance is available at low RPM and during starting, and the system can add more advance later as conditions allow, but the starting point remains the initial timing. The other terms describe how timing changes once the engine is running (rate of timing advance), the total amount of advance after all adjustments, or a condition-specific retard such as under boost, which isn’t about the baseline used during start-up or open-loop.