Yamaha FJR1300N 2001 Service Manual page 40

Air-fuel ratio compensation equipment
An O sensor is provided in the exhaust pipe upstream of the catalyst, to enable the catalyst to
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operate at a high degree of efficiency. The O
gen remaining in the exhaust gases.
A high level of oxygen concentration signifies a lean air-fuel mixture, and when the O
detects this condition, it inputs a lean signal into the ECU. Conversely, when the level of oxygen
concentration is low, the O
The ECU system applies minute corrections to these signals so that the injection volume (the dura-
tion of the current applied to the injectors) comes to be within the vicinity of the stoichiometric ratio.
Thus, the system is designed to maximize the cleaning function of the catalyst.
Illustration is for reference only.
È The ECU determines the basic injection volume based on the signals that are input from various sensors
and regulates the duration of the current applied to the injectors.
É Current is applied to the injectors, enabling them to inject fuel.
Ê The engine undergoes combustion and exhaust.
Ë The O
sensor detects the level of oxygen concentration in the exhaust gases, and outputs a lean or rich
2
air-fuel ratio signal in accordance with the detected data.
Ì In accordance with the signals from the O
tion duration, determines the subsequent injection volume, and provides instructions to the injectors.
The above processes are repeated in order to maintain the mixture at the stoichiometric ratio.
sensor detects the level of concentration of the oxy-
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sensor inputs a rich signal into the ECU.
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Feedback compensation circuit
Prolongs the duration of the current
applied to the injectors
Injection duration correction circuit
Shortens the duration of the current
applied to the injectors
Basic injection duration circuit
Signal from
various sen-
sors
Injector
sensor, the ECU applies minute corrections to the basic injec-
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FEATURES
Air-fuel ratio
judged as
lean
Lean signal
Air-fuel ratio
Rich signal
judged as
rich
O sensor
2
GEN
INFO
sensor
2