The PCM advances the spark timing upon engine startup.

The PCM advances the spark timing upon engine startup.

• A. True
• B. Sometimes
• C. During Startup
• D. False

Answer: (D)

Ignition timing during startup is controlled by the PCM using a dedicated cranking map that varies with temperature and speed. It isn’t guaranteed to be advanced at startup; in many systems the timing is kept at a safe value or even slightly retarded during cranking to prevent kickback, pinging, or excessive cylinder pressure. As the engine starts and RPM and temperature rise, the timing shifts toward the normal running values. So the statement that the PCM always advances spark timing upon startup isn’t generally correct.

Ignition timing during startup is controlled by the PCM using a dedicated cranking map that varies with temperature and speed. It isn’t guaranteed to be advanced at startup; in many systems the timing is kept at a safe value or even slightly retarded during cranking to prevent kickback, pinging, or excessive cylinder pressure. As the engine starts and RPM and temperature rise, the timing shifts toward the normal running values. So the statement that the PCM always advances spark timing upon startup isn’t generally correct.