Abstract: An engine analyzer for an internal combustion engine includes an analog-to-digital (A/D) converter which digitizes an analog input waveform representing, for example, a secondary or primary voltage waveform of the ignition coil of the internal combustion engine. The sampling rate of the analog digital converter is determined by dividing the waveform time period by the desired number of samples. An adjustment factor C is used to provide a buffer period during the sampling period of the waveform. A display for displaying the waveform has a buffer region which corresponds to the buffer period. Thus, a variation in the speed of the engine which causes the engine to slow down and extends the period of the engine waveform does not cause a loss of data collected from the waveform because the buffer period provides a margin of error.