R1150GS // Idle Switch Position odd??

[h_c_82]

Hello everybody,

After opening a topic because of connection Problems to the ABS http://forum.hexcode.co.za/forum/index.php/topic,2242.0.html I have another issue where the community might be able to help me:

My Idle switch position is off in idle and on as soon as the Throttle is off the seat. It is correctly adjusted (250mV then set to 360mV...). It is also green in the TPS adjustment procedure in the GS911. But as soon as I start the engine the position is as described. The bike runs fine (except a faulty o2 sensor but thats another story where I want open another topic) so I dont think there is something wrong with the TPS. I have a log attached where you can see it:

log file

#29.07.2018 14:54:52
#GS-911 V1807.2
#R1150GS
#Motronic MA2.4

You can see a cold start with the lever pulled in the beginning to full extend then dropped to intermediate position then closed.
Does anyone know whats up with that?

Cheers

Holger

[Nicol Carstens]

Hi Holger.

I have done a bit of testing on our own R1150GS - as you know a model very similar to your own. The short answer with regards to your TPS-Idle Switch question? What you seeing is normal - if I understand your description correctly. That's the way it should work. Bonus: once you dig into the details, it actually makes sense.

The bike has an "idle switch" (also known as a "choke") on the left handle - you know this, but stating it as a fact for those that dont or have forgotten. The reported "idle switch" monitors the position of the butterfly, not the switch. So if the butterfly is opened using the "idle switch/choke", the status reports ON. The status also reports ON if the bike butterfly is opened using the TPS. The reported "idle switch ON/OFF" is thus really the status of the "sensor" measuring the position of the butterfly as being closed or not - if you like. It gives you feedback on the position of the butterfly's position". ON implies the butterfly is not fully "closed", but rather slightly (or very much) actuated. OFF means it is closed proper! (For the sake of others: note that the GS-911 reports both the Throttle Position Sensor and the Idle Switch - these should not be confused. They are not the same thing. The idle switch said completely "closed/OFF" or "opened/ON". The TPS says open by how much.)

Like our CEO (Stephan Thiel) wrote back in 2010: "naturally if the cable to this switch is too tight, OR if the throttle is not fully released (due to friction devices or lack of free play) OR a TPS that is set horribly wrong... then the ECU will NOT see the idle switch as OFF..." - from https://groups.google.com/forum/#!topic/gs-911/kPDPc5qzf1k

“There is definitively some kind of “idle switch” function present in the TPS unit, or to be exactly, it’s calculated by the MA2.4 from the TPS position, so it’s not a hardware switch. The MA2.4 knows when you close the throttle as it cuts off fuel until 2000 rpm when braking on the engine for example.” - Jos in the same thread.

Does that make sense? If anyone else has any feedback, please feel free to correct or clarify my statement.

With thanks

Nicol

[h_c_82]

Thank you for the explanation. It follows its own logic but it does make sense.

[Nicol Carstens]

  True! Had me a bit confused as well. You are welcome.

[schuppi]

Hello all

My thoughts!
It would be correct if the throttle is closed, then the idle switch is closed.
This is exactly how it is described in other injection systems.
In order not to confuse the expert, HEX may be able to adjust this ad in a future update.

[Nicol Carstens]

My thoughts!

Noted and appreciated.

In order not to confuse the expert, HEX may be able to adjust this ad in a future update.

I always vote for reduced confusion! As the latest member of the PC App design team, I promise to look into it with the team. It had both myself and Holger confused in the last week. My understanding is that some source motivated the phrasing... but that's before my time. Will have a fresh look at it.

Best,
Nicol

[BeemerKOS]

For information - I had a TPS which after 114K miles would not give a steady output at idle. I discovered this looking at the output trace with the GS911 trying to work out what was causing a very erratic idle. The TPS was giving 350mA but then occasionally dropping to zero. So new (or 2nd hand but lower mileage hopefully) aquired and tried to fit. However the TPS setup on the GS911 kept reporting idle switch on regardless of where I positioned the TPS even onto the stop. So the only way I could set it up was using the multimeter 350mA position. This done I then started the bike and monitored the Motronic outputs. Once the engine was warm the idle switch reported as off. I could then check the TPS with the GS911. All OK, smack in the middle of the setup zone. So it would appear that the Idle Switch ON/Off may be tied to TPS position but is obviously also affected by engine temperature. The other observation was looking at the O2 trace the fuel mixture was also very rich until the engine warmed and the lamda went into closed loop.  Old topic but may be useful to someone who like me is still running the old 1150s.

[Jughead]

I had a TPS which after 114K miles would not give a steady output at idle. I discovered this looking at the output trace with the GS911 trying to work out what was causing a very erratic idle.

I have seen very few 1100/1150's give a steady output at idle.  Due to wear, the butterfly shafts often vibrate as the vacuum from the cylinders pulsates through the throttle bodies and past the butterflies.   Since the TPS is attached to the same shaft, it will give erratic readings, more so on the higher mileage bikes.