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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Fuel Injection Control


Fuel injection is controlled in two ways; open loop control and closed loop control. During open loop control, the air/fuel ratio is determined by fuel delivery time, which is controlled by the ECU. During closed loop control, the air/fuel ratio is feedback controlled by the ECI system including the exhaust oxygen sensor.