Non-Synchronized Injection Control; Fuel Cut Control - Mazda RX-8 2009 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, dechoke control, and
excessive speed fuel cut control.
Note
AT vehicles: If the engine speed reaches the excessive speed fuel cut condition with the shift lever in the
M range, fuel cut and supply occur repeatedly to warn the driver that the engine speed is too high.
Moreover, if the engine speed is not lowered, the engine speed is lowered by a forced shift up of the gear
to protect the engine.
MT vehicles: If the engine speed reaches the excessive speed fuel cut condition, the fuel is cut to protect
the engine. Moreover, if the engine speed is not lowered, fuel cut and supply occur repeatedly to warn the
driver that the engine speed is too high.
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
CONTROL SYSTEM [13B-MSP]
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 (AT).
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
— Throttle valve opening angle
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 (AT).
engine speed while vehicle is stopped.
Fuel cut is performed in case of a drive-by-wire
control malfunction which may lead to a sudden
increase in engine speed.
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.
Dechoke control is performed when the throttle
valve opening angle is 50 degrees or more at
engine start.
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