Engine analyzer with cylinder triggering of oscilloscope display having fixed-time sweep

A system for analyzing the operation of a multi-cylinder internal combustion engine in which the cylinders are fired in a predetermined firing order beginning with a no. 1 cylinder, said system comprising:

• sensing apparatus for coupling to an associated engine for generating a cylinder clock signal indicative of the firing of each cylinder and a sync signal indicative of the firing of the no. 1 cylinder,
• a waveform acquisition circuit for coupling to the associated engine for receiving analog input waveforms therefrom and generating digitized waveform data representative of such analog waveforms,
• a memory for storing the digitized waveform data,
• means responsive to the cylinder clock signal and the sync signal for identifying cylinder firings,
• a display device having a screen display with a fixed-time sweep for displaying stored waveform data,
• a processor coupled to said memory and to said display device and operating under stored program control for controlling storage and display of the waveform data for a period of time beginning with the firing of a preselected trigger cylinder, and
• a switch coupled to the processor and operable for selecting any one of the cylinders as the trigger cylinder for triggering the display device.