3-21 ENGINE CONTROL SYSTEM
CONTROL MODE
BEFORE START:
The IAC valve is always closed when engine is not running. (0% duty)
WHEN CRANKING :
The IAC valve is controlled to operate at 100% duty.
AFTER START ( FAST-IDLE FUNCTION ) :
The IAC valve is controlled to operate at 100% duty until the timer, which was set according to cylinder
temperature at cranking, expires.
WHEN IDLING / TROLLING :
The IAC valve is controlled so that the engine speed is stable at the idling / trolling speed specified.
During this period, the IAC valve has a duty cycle of approx. 20% but will vary slightly as idling / trolling
conditions change.
WHEN RUNNING ( NORMAL OPERATION ) :
The IAC valve is controlled to operate at 20 – 100% duty, which depends on the current engine conditions.
WHEN DECELERATING ( DASH-POT EFFECT):
When the throttle valve is suddenly returned to full close and the CTP switch signal changes to “ON”, the
IAC valve operates at a controlled gradual return to idle / troll operating duty to prevent engine stalling or
unstable running.
NOTE:
Due to the limited intake air flow from the IAC passage and in order to effectively use both the “Dash-pot
effect” and “Fast-idle function”, the by-pass air screw must be adjusted to provide IAC valve operation at 20
± 5% duty at the engine idling / trolling specification.
See page 2-14 for the by-pass air screw adjustment procedure.
ECM
CPU
Sensor / switch
signal input
IAC valve
Ignition
switch
Battery
30A fuse
Rectifier &
regulator
Battery
charge
coil
ECM
main
relay
Duty cycle signal for IAC valve
(example : 20% duty)
“ON” time
1 cycle time
× 100 = duty (%)
20 ms
Time
100 ms (1cycle)
OFF
ON
To Next Page
Loading...
Need help?
General
