Tech Info


IAC - Idle Actuator Calibration for all CAN-bus based BMW motorcycles

What models is it used on?

All CAN-bus based F-, K- & R-Series motorcycles… This function was available for the R-Series since their inception in 2004, but BWM recently (early 2009) qualified and introduced it for both F- and K-Series models too…

When do I need to use it...?

You typically run the Idle Actuator Calibration function when the motorcycle is suffering from poor idle… It is also recommended to run this function after removing and/or replacing any of the Idle Actuators…

What does Idle Actuator Calibration do?

Below is a quote from BMW’s Release News for the CD25/CIP13, released early 2009:

“Symptom poor idling: activate idle-speed actuator adjustment
The toolbox for BMS-KP control unit functions offers for all CAN bus models with poor idling the opportunity to carry out an idle-speed actuator adjustment. This adjustment was previously only available to boxer models and has now also been approved for the K4x and K7x Series.

Here, both idle-speed actuators of the K2x models are moved by the engine electronics control unit against the lower stop in the throttle valve assembly, i.e. the air passage is closed. On K4x and K7x models the idle-speed actuator is moved to the stop in the intake silencer. This operation enables the control unit to determine and relearn the exact position of the stepping motor in the idle-speed actuator.

The aim is – in the event of a customer complaint – first to carry out an adjustment without disassembling or replacing the component (duration < 1min) in order to check the idling immediately after a test ride.”

You can do this with your GS-911 !

We introduced the Idle Actuator Calibration function in our first Beta of 2009 where it covered the R-Series models. Since the 906 Beta release, it also covers the F- and K-Series models too!

How do the Idle Actuators work, and why do they need calibration - Stephan's short version...

The IA is a stepper motor… these stepper motors have NO position feedback… i.e. there is no way for the ECU to know exactly where the IA is… the ECU starts off at what it assumes is a known position for the IA… and then as it does its work, tells it to move X steps in one direction or Y steps into another… However, as time goes by the IA does not always move the amount of steps it is commanded to move by the ECU (this could be due to filth, friction, reaching the stop etc.)… hence, as time goes on, the ECU “thinks” an IA is at a specific position, when in reality it is in a completely different position… in reality the ECU has lost synchronization with the stepper(s).

The solution is the Idle Actuator Calibration… in the R-series, the IA’s are moved into the completely closed position (several times) and the ECU, then uses this as it’s reference for “closed”… It now has a known reference point from which to command the steppers again…

The IA’s in the R-series work similar to the idle screw in the R1150 and R1100 engines… in the throttle body of the R1200 models, there is still an idle-air bypass channel, and the IA is of the “plunger”-type… i.e. it moves perpendicular to the idle-air channel, causing more or less of an obstruction in this channel, and thus controlling the amount of air that is passed through this channel…

hope this helps!

Some more reading on the Idle Actuators and Engine synchronizing

A BMWSportTouring thread discussing throttle body sync