Regular Drive Function; Ignition Switch Off Function; Heated Oxygen Sensor (Ho2S) Heater Control Outline - Mazda RX-8 2004 Service Highlights

Fail-safe for each control
Control
Fuel injection control (pulse width at last
injection)
Ignition timing control (ignition timing)
Metering oil pump control
(Step number)

Regular Drive Function

• The PCM always calculates the optimum target step number according to the engine operation conditions, and
controls the stepping motor step number so that it is close to the actual step number in reference to the target.
• If the actual step number is less than the target
step number, the amount of stroke of the plunger
is increased by increasing the stepping motor
step number, which increases the amount of oil
delivered. If the actual step number is larger than
the target step number, the stepping motor step
number is lowered, the amount of stroke of the
plunger is reduced, and the amount of oil delivery
is reduced. (See 01–11–5 METERING OIL PUMP
CONSTRUCTION/OPERATION.)

Ignition Switch Off Function

• After the ignition switch is turned off, the PCM sets the target step to step 0 and when the actual step reaches
0, control of the metering oil pump ends.
• After the ignition switch is turned off, a main relay ON request is output and the ignition switch off function
operates. (See 01–40–10 MAIN RELAY CONTROL OPERATION.)
End Of Sie

HEATED OXYGEN SENSOR (HO2S) HEATER CONTROL OUTLINE

• Stabilized oxygen concentrations, even when the exhaust gas temperature is low, are detected by controlling
of the HO2S, enabling feedback control of the fuel injection control even during cold-engine starting, improving
emission performance when cold.
• When the exhaust gas temperature is high, the HO2S is protected from sharp rises in its temperature by
stopping energization to the O2S heater.
• Emission performance improvement and protection of the HO2S have both been achieved by the duty control
of the front and rear HO2S according to the engine operation conditions (exhaust gas temperature).
End Of Sie
01–40–34
CONTROL SYSTEM
At engine start
When the throttle
opening angle exceeds
13%.
Other
Leading side
Trailing side
Stepping motor fixed at step 7
Fail-safe
Regular control
4.50 ms + ineffective injection time
2.65 ms + ineffective injection time
Fixed at 4.88°CA
TARGET STEP NUMBER
ACTUAL STEP NUMBER
CHU0140S030
CHU014000140S39