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Low RPM throttle jerking on 12GS


GelStra

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(Gads, I hope this doesn't bring out the same wrath that was brought out in the "backfiring" thread, but, here goes.)

 

At very low throttle (in 1st gear especially), the throttle almost takes on an on/off response. If I close it down even further, the drop in power jerks me forward. It makes slow speed modulation very tough. I end up having to feather the clutch to smooth it out.

Is this normal?

In reading the "backfire" thread, it may actually be normal based on the limited amount of fuel being injected at those low RPM's. But, I would love to know the experiences of this panel of wisdom. Thanks.

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You should ride an 11GS or even a 1150GS and then you will see very low throttle herky jerky!

 

They tend to be like a switch, on or off, and the transition is abrupt at times.

 

The 12GS is smoother, but if you are just off idle and go back and forth you will feel it as kind of jerky!

 

Jim cool.gif

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Thanks, Jim. It certainly seems normal as it has done it since mile 1. But, the bike tempts you to treat it like a trial bike! On any other "normal" street bike, it wouldn't be an issue. Gas it and go!

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Go through the throttle range re-training procedure. My 12GS for some strange reason occasionally goes into the same "on/off" mode. The re-train always clears it up.

 

I believe there is a software upgrade that addresses this, but it's not available in the USA.

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Go through the throttle range re-training procedure.

 

Ken - What is that?

 

We do have software updates available here and people are saying it makes the jerkiness go away to a great extend. They also sometimes get a new set of problems to go along with the new software. Ones I read about were less power in certain parts of the band and increased fuel consumption. So I haven't had the update done yet, but I do have to same problem when low/no speed maneuvering. I’m patching it by slipping the clutch, but I know that’s not a good idea on a BMW.

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Go through the throttle range re-training procedure. My 12GS for some strange reason occasionally goes into the same "on/off" mode. The re-train always clears it up.

 

I believe there is a software upgrade that addresses this, but it's not available in the USA.

 

That is my experience, too. Every once in awhile mine will start out like that, and it is quite dangerous in a curve. I stop, retrain it, and it always goes away.

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St0nkingByte
Go through the throttle range re-training procedure.

 

Ken - What is that?...snip...

 

Maybe this:

 

Turn ignition on but don't start. Cycle throttle 2-3 times slowly from closed to full open to retrain throttle position sensor. Turn off.
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Maybe this:

 

Turn ignition on but don't start. Cycle throttle 2-3 times slowly from closed to full open to retrain throttle position sensor. Turn off.

Yes, but I never shut it back off, just start it after cycling the throttle.
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Thanks - But I'm not sure I understand the procedure yet, and I would very much like to! This is what I think you're saying:

 

Turn on the ignition. Wait for the start procedure to finish, but do not turn engine over. Now turn the throttle slowly (?) all the way to the end and back, three times. Then start the engine. (Sounds a little like a Harry Potter spell.)

 

Please tell me if this is correct and what this does, how this works. Thanks!

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Yeah, obviously, I'm curious too. ('Course, I'll wait until you try first, just in case there's a loud KABOOM that follows! JK! grin.gif)

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Thanks, but your answer seems to have confused me only further. I need to remove the battery to do this?!

And am I supposed to keep the throttle in a certain position before turning on the engine?

Can anyone please explain this procedure in layman terms that a non-technical person such as me can grasp?

Cheers!

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My '05 RT does this also. I am getting used to it but its sure different than the old slide carburetors which opened so smoothly on my other bike.

 

The procedure is to retrain the system after having no power to the bike like after replacing a battery. I dont think it will have any effect if you just do it with the bike in normal operating mode. It already has the settings learned in the computer. You dont have to remove the battery, just pull off one of the battery cables for a few minutes then reattach it and do the throttle reset process. I thought this is to tell the computer where idle and wide open throttle is. Not sure if it will change the on-off of the fuel injection system. Its worth a try .

 

I wonder if BMW can tell the system to do a slow ramp up and back down instead of the sharp on-off that it has.

 

Rich

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The procedure is to retrain the system after having no power to the bike like after replacing a battery. I dont think it will have any effect if you just do it with the bike in normal operating mode. It already has the settings learned in the computer.

 

Rich, that´s definitely not true for my bike. I can stop at a gas station and it will start up in what I call "throttle digital" mode. I can then reset it without disonnecting the battery. It´s happened four times so far.

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Miriam,

 

You have it exactly right.

 

The disconnect the battery step is for the R1150xx series. Disconnecting the battery first is not needed for the R1200xx series.

 

In the US English version of the owners manual the procedure is on page 154. Suspect it is somewhere in yours too.

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David, thanks for the clarification.

I am still trying to understand all of the changes to this new bike. Gonna take a while.

How did you know it was in "throttle digital" mode and what do you think made it go out of normal mode? Did it start and idle or run differently?

I dont think I have experienced this yet or I have and didnt know it.

 

Rich

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David, thanks for the clarification.

I am still trying to understand all of the changes to this new bike. Gonna take a while.

How did you know it was in "throttle digital" mode and what do you think made it go out of normal mode? Did it start and idle or run differently?

I dont think I have experienced this yet or I have and didnt know it.

 

Rich, I couldn't tell any difference in how it started or idled, but the first corner where you move from idle to light throttle, it's unmistakeable. Just guessing at the values, here, but it feels like it's going from 0% to 15% without any intervening values. You cannot hold a straight line in a curve. It's actually quite unnerving.

 

As Ken said, there will be no mistaking it when it happens.

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Meriam just sent me a PM regarding the term "digital mode." I believe David is using the term metaphorically to describe the failure in the bike as being 'digital like.' The throttle becomes very on/off/on/off like. "Digital" in the computer on/off, 0/1, binary sense. There is not an actual "digital mode" in the sense of some designed operational mode the bike is going into.

 

Hope this clarifies.

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Glad to see your motronic voodoo dance is helping you mask in your mind a very obvious technique issue. grin.gif

 

For some reason, the smiley I had in mind for this post wasn't among the choices. tongue.gif

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David, thanks.

Mine does the on/off to some degree but next time I take it out I will try to see if the reset method helps any. If I dont let the throttle close completely the bike is quite smooth. In first gear at very slow speed the on/off jerky motion can be very abrupt.

 

Rich

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FYI, I did the throttle cycle as was mentioned by you good folks and... thumbsup.gif MUCH smoother, especially helpful in corners. Thanks all! You're the best. Now, if I could just figure out how you people know this crap! eek.gif

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Now, if I could just figure out how you people know this crap!
Hanging around on Internet forums too much.

 

Oh, and we ride the crap out of the bikes!

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