Ignition timing

The ignition map is determined in an engine control of a spark ignition engine the ignition angle ( ignition timing ) of the individual cylinders. The ignition map is a three-dimensional structure consisting of the X-axis (rotating speed ), the Y-axis (motor load, usually obtained from the air flow, the intake manifold or the angle of the throttle valve ) and the Z- axis ( advance angle ). The firing angle is always in sync crankshaft and cylinder individually calculated in relation to top dead center ( TDC). In the development of an engine the ignition table is set with an application system so that the gasoline engine load and speed range with respect to combustion and power works best in each. To achieve an optimal operation of the engine, the resolution of the reference points of the X and Y-axis should be selected as small as possible. Since due to the limited memory and fixed-point arithmetic are mostly used in the engine control units no arbitrarily small resolution of the axes of Zündkennfelds is possible interpolation routines are used to calculate intermediate values. These functions in the software of motor control are usually in terms of maturity optimized to deliver even at high speeds always the correct interpolation.

In the application ( optimal setting ) of a ignition characteristic by means of a delivery system, consisting of a GUI and hardware that allow access to the motor controller in real time, the application programmer must make sure that it moves in a range when adjusting the firing angle of the engine causes no harm. To this end, minimum and maximum limits for the ignition angle are specified in the application system, which can not be exceeded and the application programmer.