Abstract: A self-contained handheld peak ignition breakdown voltage probe locates faulty sparkplugs in an internal combustion engine. The probe has a novel dual-polarity detection system suitable for all ignition systems, distributorless or distributor types. Each nanosecond peak breakdown ignition event is signalled by a high-intensity LED lamp lit for a fixed period of time. An adjustable calibrated threshold level provides precise control of acceptance level. Other problems such as cabling, plug gap, and relative compression may also be inferred. The simple arrangement of integrated circuits provides a novel and useful tool for locating ignition problems.

Abstract: A semiautomated diagnostic apparatus primarily used with ignition systems on internal combustion engines is novel in that every firing is examined for peak breakdown voltage level in a synchronized sequential manner to create a display of abnormalities and sequence number identification. Normal conditions can also be displayed in sequence when desired. A variable input permits examining relative peak voltages for further user analysis. An acoustic alert is provided as is an RPM indication and novel realtime indication of spark advance angle. The system operates at any engine speed.