Fuel Injection Control Operation; Fuel Injection Timing - Mazda RX-8 2004 Service Highlights

FUEL INJECTION CONTROL OPERATION

Fuel Injection Timing

• The PCM calculates the optimum fuel injection timing according to the engine operation conditions and
operates the injectors.
• The fuel injection timing is controlled at engine start and after engine start.
• At engine start (engine speed is within 500 rpm), fuel injection timing control at engine start is performed and
after determining that the engine has started (engine speed is 500 rpm or more), injection timing control after
engine start is performed.
Fuel injection timing at engine start
— The injection timing at engine start operates for a period until engine start has been determined and injects
at BTDC 455°CA (crank angle position).
Fuel injection timing after engine start
— The injection start position of the fuel injection timing after engine start is determined by the injection end
position and the final injection pulse width (injection time).
— The injection start position is calculated by: (Injection start position = BTDC 275°CA + Injection end position
+ Final injection pulse width).
— The injection end position is determined by the engine speed. (The higher the engine speed the lower the
fuel injection timing.)
Engine speed table
CONTROL SYSTEM
ECCENTRIC SHAFT
POSITION
SENSOR
SIGNAL
INJECTOR
OPERATION
SIGNAL
INJECTOR START POSITION
(BTDC)
635°CA 455°CA 365°CA
FINAL INJECTION
ENGINE
PULSE WIDTH
SPEED TABLE
OFF
ON
INJECTOR END POSITION
ENGINE SPEED
LOW
CHU014000140S20
01–40
STANDARD
POSITION
275°CA
CHU0140S018
HIGH
CHU0140S017
01–40–19