Chart 2 Detonation Check

Chart 2 Detonation Check:

Ignition System:

Circuit Description

The detonation check test for proper knock sensor operation: Possible causes of detonation include knock sensor, wiring, or PCM faults, poor fuel quality or engine mechanical conditions. This chart required J 39200 voltmeter and J 35616 jumper kit.


Notes on Chart

1. Tapping on the engine block simulates that noise created by detonation.

2. The knock sensor produces on A/C voltage proportional in amplitude to the loudness of the knock condition.

3. The PCM uses the knock sensor information to estimate the octane level of the fuel heing used. The PCM selects a spark calibration for either 87, 90, or 93 octane.

4. Fuel with an octane level below 87 may cause detonation even with properly operating engine. Engine mechanical problems such as low oil pressure, worn rods or main bearings or valve train problems may cause a knock condition.