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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Deceleration Valve: Testing and Inspection




1. Start and operate engine at idle.
2. Close off air intake port of the anti-afterburn valve and ensure engine speed does not change.
3. Increase engine speed and quickly decelerate. Air should be sucked into the intake port for 1 to 2 seconds after the accelerator is released. If air is not sucked into the intake port, replace anti-afterburn valve.