Mystery stalling

[Peter_Mc_UK]

Hi guys, I have a 2006 R1200RT that occasionally stalls when I pull the clutch in as I’m about to stop at a junction. It only happens when the bike has been running for several hours and is more common on hot days. Which leads me to believe it’s something which gets hot and then brakes a connection somewhere. 
 

Several mechanics have tried to solve this but to no avail! The last one replaced my fuel pump which sadly hasn’t fixed the issue. 
 

i was hoping that someone on this forum might have experienced the same thing and could suggest an answer please?

[dirtrider]

10 hours ago, Peter_Mc_UK said:

Hi guys, I have a 2006 R1200RT that occasionally stalls when I pull the clutch in as I’m about to stop at a junction. It only happens when the bike has been running for several hours and is more common on hot days. Which leads me to believe it’s something which gets hot and then brakes a connection somewhere. 
 

Several mechanics have tried to solve this but to no avail! The last one replaced my fuel pump which sadly hasn’t fixed the issue. 
 

i was hoping that someone on this forum might have experienced the same thing and could suggest an answer please?

Morning Peter_Mc_UK

 

That type of stall after riding for a while usually points to one of the idle steppers (idle control device)  getting lost so the actual counts  the stepper is at (how far pintle is open) doesn't match the counts the computer has commanded. 

 

A stepper getting lost is typically due to wear on the pintle drive threads (very difficult to find by just looking at the steppers. 

 

Your 1200RT has a stepper (idle control device) on each side (one for each cylinder) so it could be either side, or both sides, but typically it in only one side. 

 

I have had some luck in finding the bad stepper side by connecting my GS-911 with a longer adapter cable, then setting it up to trap real-time data,  then riding the motorcycle at a steady speed for a while.  Then pulling over to a normal stop every so often (it needs to be pulled over before a stepper gets so lost that you actually get an engine stall). You probably have to do this a few times as the steppers need to be in independent mode  not linked mode to find it in the trapped data as there will be no big smoking gun, just a small correction in the stepper commanded counts.

 

Of just buy one stepper (idle control device) then install that on one side, if the stalling goes away then you have found the side, if it still stalls then reinstall the original stepper on that side & install the new stepper in the other side.   

 

Not 100% but your stalling compliant after riding for a while (especially if that ride was at a constant speed on the freeway or at a constant throttle setting) usually points to a lost stepper (idle control device).  

[Peter_Mc_UK]

Thanks Oracle! That’s a very interesting solution and one that I’ll definitely look into. I’ve discussed your reply with my mechanic and will drop it over to him tomorrow to take a look. 
 

I’ll let you know what he finds. 
 

Thanks

Peter

[dirtrider]

19 minutes ago, Peter_Mc_UK said:

Thanks Oracle! That’s a very interesting solution and one that I’ll definitely look into. I’ve discussed your reply with my mechanic and will drop it over to him tomorrow to take a look. 
 

I’ll let you know what he finds. 
 

Thanks

Peter

Morning Peter

 

If your mechanic is not familiar with the BMW stepper type idle control make sure to tell him not to remove a stepper then turn the key on to test it.  That will instantly screw the pintle all the way out so it will fall out of the housing,  that pintle is a REAL PAIN IN THE A$$ to get to go back into the stepper motor assembly. 

 

If he doesn't have a GS-911 then possibly he can find the problem by  putting  somewhat matched vacuum gauges of each side throttle body nipple then riding the motorcycle far enough to get the dropped throttle stall (compare the closed throttle side to side vacuum just before the stall). The highest vacuum side is probably the lost stepper side. 

 

 

[Peter_Mc_UK]

My mechanic couldn’t find anything wrong using his scanner but we agreed that he’s replaced both stepper idle modules along with the throttle position sensor. All parts are second hand off a know good R1200R which the garage owns. We are touring in France for the next couple of weeks so will soon find out if that’s fixed the issue. 

[dirtrider]

7 hours ago, Peter_Mc_UK said:

My mechanic couldn’t find anything wrong using his scanner but we agreed that he’s replaced both stepper idle modules along with the throttle position sensor. All parts are second hand off a know good R1200R which the garage owns. We are touring in France for the next couple of weeks so will soon find out if that’s fixed the issue. 

Morning Peter

 

Using a scanner to find a stepper issue (like a lost stepper) is difficult unless you REALLY know how to use the limited data the scanner gives you.  The problem is the only thing the scanner sees is the commanded stepper counts, a scanner can't see the actual stepper pintle position as BMW uses 4 wire idle steppers that can't/don't report their ACTUAL pintle  position.  Basically the scanner can only see where the stepper pintles are commanded to go not where they actually are, so if a stepper is lost & is 10 counts behind actual position the fueling computer commands their new position (to prevent a stall)  based on where they were last  COMMANDED to go not from where they actually are at time of new position command).  

 

The scanner needs to be active at stall (actually just before the stall) with steppers being in independent control (as long as they stay linked to a single command count the scanner can't tell one side from another). There are very subtle indicators in the scanner data but unless you know exactly where to look & how far back in the data stream to look most scanner users will miss the indicators. 

 

If you trap active riding data for a long enough ride (under the conditions that lead to the steppers getting lost),  like at long steady throttle runs, then crunch the data in a spread-sheet, there are usually little (easy to miss) indicators that a stepper is becoming lost.  

[Peter_Mc_UK]

So 3000 miles done now with replacement idle steppers and throttle position sensor and no sign of my stalling issue!! Looks like that has done the trick 😃

 

Thanks very much for your advice dirtrider, it’s very much appreciated 😊👍