Non-Synchronized Injection Control; Fuel Cut Control; Fuel Pump Control Outline - Mazda RX-8 2004 Service Highlights

Non-synchronized Injection Control

• The non-synchronized injection control allows fuel injection when fuel injection conditions are met, regardless
of the position of the eccentric shaft.
• The non-synchronized injection control includes non-synchronized injection control at engine start,
acceleration, idle, and fuel cut recovery.
Control name
Non-synchronized injection
control at engine start
Non-synchronized injection
control at acceleration
Non-synchronized injection
control at fuel cut recovery

Fuel Cut Control

• The fuel cut control stops fuel injection when the fuel cut conditions are met.
• The fuel cut control includes traction fuel cut control, continuous fuel cut control during high engine speed, fuel
cut control during drive-by-wire abnormality, fuel cut control during deceleration and dechoke control.
Control name
Traction fuel cut control
Continuous speed fuel cut
control during high engine
speed
Fuel cut control during
drive-by-wire abnormality
Fuel cut control during
deceleration
Dechoke control
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FUEL PUMP CONTROL OUTLINE

• When the eccentric shaft position sensor signal is input to the PCM, the fuel pump relay turns on and the fuel
pump operates.
• When input from the eccentric shaft position sensor signal stops, the fuel pump relay turns off and the fuel
pump turns off.
• For improved startability when the ignition switch is turned from off to on, the fuel pump is operated for several
seconds. Due to this, fuel pressure increases rapidly for improved startability.
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CONTROL SYSTEM
Purpose
Improves engine startability.
Prevents acceleration hesitation and lean air/
fuel ratio due to delay of fuel injection during
sudden acceleration.
Prevents engine hesitation and lean air/fuel
ratio due to the delay of fuel injection during
fuel cut recovery.
Purpose
Lowers engine torque based on the torque
down request from DSC HU/CM and TCM.
Prevents overheating of the catalytic converter. Performs fuel cut during continuous high
When there is a malfunction in the drive-by-
wire, fuel cut is activated and excess increase
in engine speed is prevented.
Prevents overheating of the catalytic converter
due to misfire for improved fuel economy.
Performs fuel cut on one rotor for reduced
deceleration shock.
Scavenges operation chambers to improve
engine startability if the spark plugs are
smoldered.
Injection condition
• Performs non-synchronized fuel injection at
engine start until determining the engine
has been started (engine speed 500 rpm or
more).
• Injection pulse width at engine start is
calculated by adding the injection amount
at engine start calculated from the following
signals to the ineffective injection time:
— ECT
— Engine speed
— Throttle valve opening angle
— BARO
• Performs non-synchronized fuel injection
when the amount of throttle valve change is
at the fixed value or more for both rotors
simultaneously.
• Injection pulse width is calculated from the
following signals:
— Charging efficiency
— Throttle valve opening angle
— Engine speed
— ECT
• Performs non-synchronized fuel injection
during fuel cut recovery.
• Injection time is determined by ECT.
Fuel cut condition
Performs fuel cut based on torque down
request from DSC HU/CM and TCM.
engine speed while vehicle is stopped.
When there is an abnormality in the drive-by-
wire (when related DTCs are stored in PCM),
performs fuel cut only on the front rotor.
Performs fuel cut on one rotor when the throttle
valve is open during deceleration. Performs
fuel cut on both front and rear rotors when
throttle valve is fully closed.
Performs dechoke control when the throttle
valve opening angle is 50° or more.
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