F650GS model 2004 twin spark well maintained, 65,000 Kms, recenty
serviced Oil, both filters, spark plugs replaced, Iridium spark plugs,
K&N filter, no other modifications


During the last weeks I am facing the following problem:



1. When motorbike is started the rpm is fluctuating between 1500 rpm
and 2200 rpm (not steady up and down)
2. Sometimes when it has been stopped for about 20 minutes and then
restarted the idle rpm goes up to 3500 and then slowly –slowly to the
normal figure 1500rpm.
3. Just to mention that this is happening always at the beginning
(when it is started) and after a while (5-10minute) it reaches the
normal figure 1500rpm
4. A couple of days ago, when it was quite cold about 10 degrees
Celsius, and when moto was initially started it went up to 3000-3500
rpm reaching the normal idle rpm after 5 minutes driving .
5. Moreover when motorbike is in this phase (high rpm after starting)
and you release the clutch without increasing the throttle, the rpm
are increased automatically (like sensing that more power is required
and the “governor” is being involved). After a couple of minutes the
RPM are lowered automatically, but this behavior is noticeable.
I did check all connector with sensors, checked for leaks, opened and
cleaned the “cold starting idle motor/relay” (small black barrel on
the throttle body) and then adopted the throttle (by clearing the
values and re-adapting procedure given by BMW) after throttle removal
and cleaning with my “GS911” interface. But again this morning the
motorbike started with 3500 rpm (temperature about 15 degrees
Celsius).


I have checked the errors in the ECU and even after testing them with
procedures given by the “GS911” no error appeared.



I have replaced the following:
A. idle control valve
B. Ar intake temperature sensor
C. Coolling water temperature sensor
D. Cleaned all the contacts existing at the side of the cylinder
(generator, pickup sensor etc...) including the engine grounding.
E. Did the adaptation by using the GS-911 when Idle control valve on
the throttle body is removed/cleaned.


Same behavior as above described.



All above items were replaced with brand new original BMW spare parts
Has anyone similar experience or can guide me through, what to check
by using the GS911 interface?


I am now suspecting the O2 sensor.

I have to stress the fact that when engine is cold (just started) it
is working fine (idle 2000 rpm dropping to 1500 rpm. When it is warm
(engine working temperature) we face this irregularity in the idle
speed.

Reset the BMS-C unit

thank you for the answer which helped me identify the condition of the O2 sensor.
1. It is Ok since it follows the typical plot. Furthermore I have asked a friend with an older model (single spark) and plotted his O2 sensor behavior which is almost similar.
2. About the reset of the BMS-II, which I have done a couple of times I have observed the following:
a. Motorbike is cold (environmental temperature). Did the reset and then started the moto up to the moment the fan starts. It takes about 10-15 minutes for the fan to start. Idle fluctuates up to the moment it stabilizes and everything seems OK for the next couple of days.
b. Motorbike is Hot (after having her driven/returned from the job)-(engine temperature about 90-95 degrees Celsius).Did the reset and then started the moto up to the moment the fan starts. It takes about 3-4 minutes for the fan to start. Idle stabilizes at 1500 rpm and moto seems to work better for the next couple of days, than following the previous “cold reset” procedure.
c. Motorbike is in operation. I have tried to reset the BMS-II and it does not allow me “ No response from the controller” is the message I am getting in the GS911 program
3. I do not know how the GS911 is resetting the BMS-II is working, but is it possible not o clear the data, or clear partially the memory of the BMS-II. I cannot understand why at the very beginning everything is working fine and after having driven the motorbike for a couple of days, she starts behave the same.
4. After having reset the BMS-II do I have to switch off and on the motorbike switch in order to re-boot the BMS-II?
5. I have been said by another person in another forum that he heard that it was necessary to have the BMS-II reset up to nine (9) times to finally learn the new values.
6. Finally another observation I have made about the idle rpm is that if the motorbike is left under the sun (temperature about 25-28 degrees Celsius) the idle goes up to 3000 rpm dropping to 2000 rpm (500 rpm higher than the normal). If I switch off the motorbike and then on sometimes it returns to 1500 rpm and sometimes remains to 200rpm.
7. I did logging of the values and I do have a *.csv file. Is there someone who has a similar logging?
It is strange unless the BMS-II has a corrupted program (firmware). This software has been updated by BMW 6 months ago to the version 210E.
Any comments/advices to the above may be appreciated.