Detonation Sensor
- Connect an adjustable timing light or magnetic timing light to the engine. Start engine and run it to at least 1200 RPM. Connect an auxiliary vacuum supply to vacuum transducer and apply 16 in. Hg. Tap lightly on intake manifold near detonation sensor with a small metal object.
- Using a timing light look for a decrease in spark advance. The decrease in timing should directly respond to the strength of the tapping. The maximum decrease in timing is 20 degrees. Shut off engine and disconnect timing light.