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 Fuel Cut-Off

Deceleration fuel cut-off is a function of the ECU. When the throttle is closed, the reduced air flow through the air mass sensor causes the ECU the reduce the duty cycle to the fuel injectors, which reduces the amount of fuel injected. If the idle switch is closed and the engine speed is greater than a specified rpm, the ECU cuts the duty cycle to the injectors until either the idle switch is opened again, or the engine speed drops below the specified rpm, then fuel injection is resumed.