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XDI200 Manual Version 0.1
- Page 70 -
©2017 Electromotive, Inc.
Go to the idle speed window and enter the following values:
Error Sensitivity (+): 70 (when RPM is below target)
Error Sensitivity (-): 70 (when RPM is above target)
Rate-of-Change Sensitivity (+): 1 (when RPM is increasing)
Rate-of-Change Sensitivity (-): 220 (when RPM is decreasing)
Click on the Min/Max Dutycycle button and enter values according to which idle motor you
are using.
Ford: Min = 1, Max = 255, Allow shutdown should be checked
Honda: Min = 50, Max = 188, Allow shutdown should be checked
Bosch (should be most German cars): Min = 100, Max = 255, Allow shutdown should be
checked
Mazda: Min = 60, Max = 155, Allow shutdown should not be checked
Electromotive Stepper: Min = 50, Max = 185, Allow shutdown does not effect this motor
Pick your idle targets as discussed in Section B.8
Make sure to pick the control motor type (2- or 4-wire).
If you are using a 3-wire motor, you must have a 3-wire converter box. Select the 2-wire
setting and connect your motor using the 2-wire to 3-wire converter.
Reset position sets the position that the idle motor will be in after the RPMs drop below the
Decel limit. A good starting point for this value is 8.
8.4.2 Idle Speed primer
This idle is a bit complex and can be a bit tough to familiarize yourself without having seen such a
system before. However, the process should not be terribly difficult to get through.
The Error Sensitivities define the sensitivity to the difference between the current RPM and the
desired RPM. In order to prevent stalling, the rate at which the engine slows down must also be
monitored so that the RPMs can be caught to prevent stalling. This is done with the Rate-of-
Change Sensitivities. A large value should generally be used with falling RPM and a smaller
value should be used with the rising gain. The Error Sensitivities and the Rate-Of-Change values
are calculated separately and then added together. This allows the case where the RPM may be
higher than the target RPM, but because it is falling rapidly, the idle motor will actually begin to
open, to prevent idle droop or a stall. Below are some graphic examples of how these parts work.
8.4.3 Getting the IAC Started
Attempt to start the engine. If the engine starts hard, try reducing the maximum duty cycle until
the startup revs are under control. Unfortunately, this trick does not work with the 4-wire IAC. If
the engine starts too hard with the 4-wire, try increasing the Positive rate-of change to help arrest
high startup revs.
After starting the engine the first time, chances are that it will not hold idle. In some cases, the
idle will be stable, or nearly stable. But most of the time, the engine will oscillate and possibly die.
Increase the minimum duty cycle until the engine runs without stalling. Once you have done this,
you can adjust the minimum duty cycle back down until the desired idle speed is achieved.
Generally you will want the engine to idle with an IAC reading of 1-2%. If you decreased the
maximum duty cycle very much to stop hard starts, you may consider adjusting your throttle plate
instead of increasing the minimum duty cycle.
