Data acquisition for use in determining malfunctions of cylinders of an internal combustion engine

Apparatus for use in determining malfunctions of cylinders of an internal combustion engine, comprising:

• means for providing a succession of electrical pulses respectively corresponding with successive crankshaft positions as the crankshaft of said engine rotates through at least one engine cycle, the time duration between successive said pulses corresponding with the time interval occurring as the crankshaft moves through the associated successive crankshaft positions, and wherein one engine cycle includes a plurality of power periods corresponding in number with the number of cylinders in the engine being tested and wherein each power period includes a plurality of said crankshaft positions;
• time interval measuring means responsive to said pulses for measuring the time interval between successive said pulses such that N successive time interval measurements are made for each engine cycle having N successive crankshaft positions;
• means for providing N successive time interval samples for each engine cycle wherein each said sample has a value corresponding with an associated measured time interval;
• means for utilizing said interval samples for determining cylinder malfunctions of a said engine;
• and,
• said time interval measuring means includes first and second counting means, a source of evenly time spaced clock pulses, first gating means responsive to a first crankshaft position pulse for passing said clock pulses to said first counting means to be counted thereby while blocking passage of said clock pulses to said second counting means, second gating means responsive to the next succeeding said position pulse for blocking passage of said clock pulses to said first counting means while passing said clock pulses to said second counting means.