Inventors:
Zoltan Voross - Elgin IL
James R. Caruth - Des Plaines IL
Yam C. Leung - Blommingdale IL
Assignee:
Sun Electric Corporation - Chicago IL
International Classification:
G01L 326
Abstract:
The disclosure describes apparatus for disabling selected cylinders of an internal combustion engine operated by periodic cycles of ignition signals. The apparatus prevents one or more predetermined ignition signals in each cycle from energizing engine components, such as spark plugs, which normally receive the ignition signals. In order to achieve this purpose, a clock pulse generator generates a uniform pulse in response to the receipt of each ignition signal from the engine. Three bistable flipflop circuits are used to produce output signals having states representative of the number of clock pulses received from the clock pulse generator. Gating circuitry returns the output signals to an initial state after receipt of a predetermined number of clock pulses, such as the number of cylinders in the engine being diagnosed. As the apparatus commences operation, removable setting means set the output signals to their initial state by means of a setting pulse generated by one of the ignition signals. The repetition rate of the setting pulse is divided before being applied to the flipflop circuits in order to improve the diagnostic usefulness of the system.