Mazda 2006 MX-5 Service Highlights page 146

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
(Fuel injection time, calculation method, or determination method)
Injection time at start
Basic injection time
Fuel cut
Ineffective injection
time
Volume increase
correction at engine start
Front HO2S feedback
correction
Rear HO2S feedback
correction
D-range correction
(AT)
01–40–22
CONTROL SYSTEM
Contents
Set value according to engine coolant temperature (low engine
coolant temperature→long injection time)
Basic injection time = charging efficiency x fuel flow coefficient
Fuel injection time = 0
Set time according to injector performance
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
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 electromotive force is approx. 0.45 V or
more→volume decrease correction
• Front HO2S electromotive force is approx. 0.45 V or
more→volume increase 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
Purpose: Ensures engine speed stability during D-range shifting
Correction condition
• Throttle valve fully-closed and shifted into D range
Correction amount
• Low engine coolant temperature→large correction
A: Fuel injection time base, B: Correction for fuel injection time
Control zone
A
A A
A A
A A A
B B
B
B
B