Air/Fuel Ratio Control - Mazda RX-8 2004 Service Highlights

Air/fuel Ratio Control

• Controls the fuel injection amount so that the actual air/fuel ratio is close to the target air/fuel ratio, to boost
purification of the catalytic converter.
• air/fuel ratio feedback and target air/fuel ratio feedback are adopted for precise control of the air/fuel ratio.
• The air/fuel ratio feedback compares the air/fuel ratio in the exhaust manifold detected by the front HO2S and
the target air/fuel, and feeds back the air/fuel ratio difference to the final fuel pulse width (fuel injection amount).
• The target air/fuel ratio feedback compares the air/fuel ratio in the catalytic converter detected by the rear
HO2S with the target air/fuel ratio and feeds back the air/fuel ratio difference to the stoichiometric air/fuel ratio
(λ = 1). Due to this, the optimum target air/fuel ratio is determined.
• Repeats feedback to the target air/fuel ratio and final fuel pulse width (fuel injection amount), and by constantly
calculating the optimum target air/fuel ratio and final fuel pulse width, purification of the catalytic converter at a
high level has been achieved.
TARGET AIR/
FUEL RATIO
FEEDBACK
01–40–20
CONTROL SYSTEM
TARGET AIR-FUEL RATIO
STOICHIOMETRIC AIR/
CORRE-
FUEL RATIO (λ=1)
CTION
COMPARING
ACTUAL
AIR/FUEL RATIO
REAR HO2S
FRONT HO2S
CATALYTIC CONVERTER
PCM
FINAL FUEL PULSE WIDTH
(FUEL INJECTION AMOUNT)
COMPARING
ACTUAL
AIR/FUEL RATIO
λ (lambda) = (actual air/fuel ratio) / (stoichiometric air/fuel ratio)
AIR/FUEL
RATIO
FEEDBACK
FUEL INJECTOR
ENGINE
CHU0140S082