Detonation Sensor Test
- Connect a variable timing light to engine. Start engine and run it on second highest step of fast idle cam (about 1200 RPM). Connect an auxiliary vacuum supply of 16 in. Hg to the vacuum transducer.
- Using a small wrench, tap lightly on manifold, near the sensor. With timing light, look for a decrease in spark advance. The amount of timing decrease should be in proportion to the strength and frequency of the tapping. Maximum decrease in timing should be 11°. Turn engine off and remove timing light.