AEM 30-6905 Universal Programmable EMS-4 - Manual (Page 155)

Page 155 of 279 EMS-4 Install and Tuning Guide_Rev 1.6
The Idle % vs Target table is used as the open loop set point vs target RPM. When entering
into the idle control function, the ECU will command the output duty cycle to the value defined in
this table. For example, using the table above if the current idle target is 1400 RPM, the ECU
will command an IAC duty cycle of 40% then check to see if the actual engine speed is equal to
the target RPM. If it is, no changes are made. If it is not, the ECU will adjust from this point.
The RPM Offset vs Start table is used to add an extra amount of idle air bypass immediately
after starting. This extra amount is decayed over a period of time defined in this table. In the
example above, an offset of 500 RPM will be added to the base target value and this extra
amount will decay over a period of 10 seconds. If the base target was 1000 RPM, the ECU will
target 1500 RPM at first then control the RPM down to 1000 after 10 seconds. This RPM flare
will help the engine transition from crank/start to normal idle smoothly.