Spark advance

How many crank degrees before top dead center the spark plug fires.

Spark advance is the timing, measured in crank degrees before top dead center (BTDC), at which the plug fires relative to piston position. Because combustion takes time, the charge is lit early so peak cylinder pressure lands just after TDC, where it does the most work. More advance generally makes more torque, up to a limit, but too much pushes the engine into knock. In HP Tuners VCM Editor you edit it in the Spark tab, primarily the main high-octane spark table mapped by RPM versus cylinder airmass or MAP, plus low-octane and various correction/adder tables. In VCM Scanner you log the actual commanded value via the Spark Advance PID. Safety-wise, advance is the single most dangerous parameter to add blind: change it in small steps (1-2 degrees), watch knock retard, and never chase torque past the point where the engine starts pulling timing.