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20.2 Idle speed control
This ECU can control idle speed through electronic throttle, step
motor, PWM valve and by timing.
To enable the idle speed control by electronic throttle, it is needed to
you can follow this menu to setup idle parameters.
Idle speed by timing: this control uses a target RPM for idle speed
and works advancing and retarding the engine timing to keep the engine
running near the specified RPM.
As the FT500 idle speed control has an advanced integration with the idle speed by timing control, this one stays
always enabled when any other kind of idle speed control is selected. By
doing this, the idle speed actuator is always kept in a position where the idle
speed by timing control can set the timing away from the maximum and
minimum timing positions.
It is essential for the idle speed by timing control that the engine is
equipped with a TPS sensor in perfectly working condition as this control only
starts when TPS stabilizes on 0%.
Maximum and minimum timing limits: these values are the limits for
advance and retard when ECU is controlling the idle by timing.
Position on idle
Automatic: in this mode, idle actuator is automatically opened and
closed by the ECU in order to make the engine idle near the target RPM.
Fixed: in this option, idle actuator assumes a fixed position, set up
later according to engine temperature. This option is recommended for
engines with high profile camshafts, where the automatic idle control is not
able to stabilize idle RPM.
Actuator reaction level: this parameter is the aggressiveness that the
timing and the actuator will be changed of position in order to control a RPM
fall. The higher this number, the more aggressive is the reaction of the control.
High reaction levels may lead the idle speed to be unstable.
Idle speed valve or ETC reference position: this parameter is the
actuator position when the engine is turned off or cranking. It is also used as a
s
enough for a cold start of the engine. Start with a value around 4% for
electronic throttle and 30% for step motor.
RPM for idle speed: this
table tells the ECU the target RPM the idle control will assume, according to
engine temperature.
On intermediate temperature ranges, target RPM is automatically
interpolated.
this table represents the
actuator position X engine temperature.
Post-start position: this parameter is a RPM increase (or % of
increase in the actuator position for fixed idle position). The table shows the
actuator position according to time post engine start.
A/C compensation: when one of the auxiliary outputs is configured as
A/C control, this compensation value will be added to the currently selected
opening value for the idle speed actuator in order to compensate the extra
this compensation value will be added to the currently selected idle speed
actuator opening value.
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