Specifications

CONTROL SYSTEM [LF]
01-40–3
Mazda MX-5
• When the following conditions continue for 10 s or more:
— Vehicle is stopped.
— Engine speed is 6,500 rpm or more.
— Engine coolant temperature is approx. 40 °C {104 °F}.
Note
• The PCM determines that the driver continues to unintentionally depress the accelerator pedal
Determination of fuel injection time
• Fuel injection time is set to 0 (fuel cut).
Deceleration fuel cut zone
Purpose
• Improved fuel economy
• Prevents overheating of the catalytic converter
Control conditions
• When the engine conditions are as follows (10 s or longer after engine start):
— Fully closed throttle valve
— When the engine speed is at set value or more (differs depending on the ECT) (charging efficiency at fixed
value or more, mass airflow sensor normal)
Determination of fuel injection time
• The fuel injection time is set to 0 (fuel cut).
Calculation method list for fuel injection time
A: Fuel injection time base, B: Correction for fuel injection time
Contents
(Fuel injection time, calculation method, or determination method)
Control zone
Injection time at start Set value according to engine coolant temperature (low engine
coolant temperature→long injection time)
A
Basic injection time Basic injection time = charging efficiency x fuel flow coefficient AA
Fuel cut Fuel injection time = 0 AA
Ineffective injection
time
Set time according to injector performance
AAA
Volume increase
correction at engine start
Purpose: Maintains stability of engine speed just after engine start
Correction condition
• Specified time according to engine coolant temperature directly
after engine start
Correction amount
• Low engine coolant temperature→large correction
• Low intake air temperature→large correction
BB
Front HO2S feedback
correction
Purpose: Controls air/fuel ratio to the theoretical air/fuel ratio
Correction condition
• When engine coolant temperature is at set value or more
Correction amount
• Front HO2S current value 0 mA or less→volume decrease
correction
• Front HO2S current value 0 mA or more→volume increase
correction
B
Rear HO2S feedback
correction
Purpose: Corrects feedback amount according to deterioration of
front HO2S and catalytic converter
Correction condition
• Engine coolant temperature is at set value or more
• Engine speed is 500—4,250 rpm
• Charging efficiency is 10—80%
Correction amount
• According to rear HO2S electromotive force→correction
B
Start Feedback
High load volume increase
Excessive speed fuel cut
Deceleration fuel cut
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