Operation CHARM: Car repair manuals for everyone.
Manuals through 2025 now available!

Our trusted friends have launched a new website named LEMON, which has newer manuals. It also contains all the CHARM manuals.

LEMON is the spiritual successor to CHARM, I recommend you try it!

Link: lemon-manuals.la or lemon-manuals.org.ua

(Some people have issue connecting. LEMON is investigating. For now, use Firefox or change your DNS server)

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Knock Retard

RANGE 0-90 Degrees
The Adaptive Knock Retard indicates the long term amount of the spark advance the PCM removes from the Ignition Control (IC). The PCM responds to the Knock Sensor (KS) signal.