Component Inspection
If the engine "pings" excessively and base timing is okay, check the on-board diagnostic system. If either knock sensors or knock control unit experience a problem, malfunction code 05 will set.
To perform a basic check, hook up a timing light and tap on the engine block near either sensor while observing the timing marks. Timing should retard when the artificial "knock" created by tapping is detected by a sensor and relayed to the knock control unit.
Knock control unit input voltage can be checked at ECU terminal 2M. With ignition "ON" and engine running at idle, voltage should be 4.0 - 5.0V.