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#999212 - 10/18/17 01:48 PM Re: Possible way to adjust messed up TB stop screws [Re: dirtrider]  
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14TLC Offline
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Originally Posted by dirtrider
Originally Posted by David

If it was so simple :-) When steppers are disconnected, the BMSK will run with predetermined fueling map and making the adjustment useless when connected again. You can adjust matching vacuum at any TB butterfly position. But which is the correct one that will allow specified air volume with range for steppers for correction.

Disconnected and parked steppers are different things altogether.


Morning David

I don't believe this to be true--- On the BMW 1200 the steppers are 4 wire steppers so there is NO direct feedback of stepper position or operation to the BMS-K. Therefore it should still run in closed loop with dynamic fueling correction even with the steppers disconnected.


What I have noticed is that with steppers disconnected the lambda correction factor reading got fixed value of 1.0...... and not changing.

What do you mean with "NO direct feedback"

#999215 - 10/18/17 02:03 PM Re: Possible way to adjust messed up TB stop screws [Re: 14TLC]  
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dirtrider Offline
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Morning 14TLC

I still can't confirm that TPS re-learn procedure that you at using (doesn't seem to be a reasonable way to re-set/re-teach a TPS & I sure don't show it in any of my BMW service bulletins. (are you sure this wasn't used on a fly-by-wire electronic throttle control bike? )

In any case I haven't had to do a curb idle screw (best hope resetting) on the BMW camhead.

I have done 2 BMW hexheads & a few BMW 1150 bikes. The 1150 (non stepper) bikes are easy to get back close to where they should be as there isn't that darn stepper control to confound the setting issue.

On one 1200 hexhead I was able to match the blue indexing paint up on one side then simply matched the other side using the known good side as a qualifier (this one worked out great & I had total confidence in the setting being close to factory base air flow)

The other hexhead was a pest to work with as the blue indexing paint was totally gone. The saving thing on this one was I had a very similar 1200 bike (my own) to run at the same time to compare stepper counts & throttle follower action.

I started out with both side curb idle screws set identically at EXACTLY 1/2 turn in from a fully closed (verified closed) throttle plate (that gave me a known & fairly even starting point & actually gave fairly close stepper counts at initial hot engine idle curb idle)

Once I got the hot engine stepper count (& cross side idle vacuum delta) fairly close I then ran the engine RPM up to just above the stepper link up & set the mid throttle cross side balance. (this is the important setting & the one that you ride around in the most)

I then cleared all the BMS adaptives then tweaked they base curb idle screws to get the hot engine, closed loop stepper count to be close to the known good bike (didn't take much).

I then shut engine down then checked BOTH SIDE initial TB throttle cam lift off the base idle screws (it was off just slightly) so I went back through it again using the existing base idle screw settings as a starting point (very little changes).

I'm not sure if I got it back to the initial factory/vendor) base screw setting but the bike ran good, idled good, started good, didn't die at dropped throttle after a long hiway run & seemed to have a stable curb idle (the owner says it still runs great).


D.R. ___
Sent from my rotory dial wall phone!
#999221 - 10/18/17 02:21 PM Re: Possible way to adjust messed up TB stop screws [Re: 14TLC]  
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dirtrider Offline
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Originally Posted by 14TLC


What I have noticed is that with steppers disconnected the lambda correction factor reading got fixed value of 1.0...... and not changing.

What do you mean with "NO direct feedback"


Morning 14TLC

With a 4 wire stepper (2 wires high & 2 wires low) the fueling computer has no idea where the stepper count REALLY is as the steppers have no way of reporting their position back to the fueling computer. (there is no position feedback circuit back to the fueling computer)

At initial (pre start) key-on the fueling computer commands both steppers to home (completely closed pintals) then assigns that position as "0" counts. From then on (on this run cycle) the fueling computer only knows where the steppers are by how many counts it has commanded each to move.

So basically if-- the computer starts out with a 100 count command then commands a 3 count extend it knows the stepper count should be at 97 counts it then commands another 2 count extend it now knows the counts should be at 95 counts (the computer ONLY knows where it starts & where each command puts it) so if a stepper loses a count or slips a thread the computer doesn't know the stepper pintles exact position it only knows the pintles COMMANDED position.


D.R. ___
Sent from my rotory dial wall phone!
#999223 - 10/18/17 02:27 PM Re: Possible way to adjust messed up TB stop screws [Re: dirtrider]  
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dirtrider Offline
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Originally Posted by 14TLC
What I have noticed is that with steppers disconnected the lambda correction factor reading got fixed value of 1.0...... and not changing.


Morning 14TLC

I'm not sure on this one but could be as simple as-- with the steppers disconnected the base air flow remains extremely constant so the o2 sensors can then easily hold closed loop fueling constant.


D.R. ___
Sent from my rotory dial wall phone!
#999249 - 10/18/17 09:11 PM Re: Possible way to adjust messed up TB stop screws [Re: dirtrider]  
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14TLC Offline
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Originally Posted by dirtrider
Originally Posted by 14TLC
What I have noticed is that with steppers disconnected the lambda correction factor reading got fixed value of 1.0...... and not changing.


Morning 14TLC

I'm not sure on this one but could be as simple as-- with the steppers disconnected the base air flow remains extremely constant so the o2 sensors can then easily hold closed loop fueling constant.



Could be. But even if it is like that, the injection period should vary as engine and air temperature raises, thus varying the fuel quantity. The fuel itself caries oxygen so there should be slight variation. I will double check this when bike comes over again for week or two. Just to be sure and understand what BMSK is doing in this state.

#999251 - 10/18/17 09:16 PM Re: Possible way to adjust messed up TB stop screws [Re: 14TLC]  
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dirtrider Offline
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Originally Posted by 14TLC

Could be. But even if it is like that, the injection period should vary as engine and air temperature raises, thus varying the fuel quantity. The fuel itself caries oxygen so there should be slight variation. I will double check this when bike comes over again for week or two. Just to be sure and understand what BMSK is doing in this state.


Evening 14TLC

With the steppers disconnected just pull a vacuum plug (or evap hose) off the bottom of a TB then see what you get.


D.R. ___
Sent from my rotory dial wall phone!
#999276 - 10/19/17 09:14 AM Re: Possible way to adjust messed up TB stop screws [Re: dirtrider]  
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14TLC Offline
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Originally Posted by dirtrider


The other hexhead was a pest to work with as the blue indexing paint was totally gone. The saving thing on this one was I had a very similar 1200 bike (my own) to run at the same time to compare stepper counts & throttle follower action.

I started out with both side curb idle screws set identically at EXACTLY 1/2 turn in from a fully closed (verified closed) throttle plate (that gave me a known & fairly even starting point & actually gave fairly close stepper counts at initial hot engine idle curb idle)

Once I got the hot engine stepper count (& cross side idle vacuum delta) fairly close I then ran the engine RPM up to just above the stepper link up & set the mid throttle cross side balance. (this is the important setting & the one that you ride around in the most)

I then cleared all the BMS adaptives then tweaked they base curb idle screws to get the hot engine, closed loop stepper count to be close to the known good bike (didn't take much).

I then shut engine down then checked BOTH SIDE initial TB throttle cam lift off the base idle screws (it was off just slightly) so I went back through it again using the existing base idle screw settings as a starting point (very little changes).

I'm not sure if I got it back to the initial factory/vendor) base screw setting but the bike ran good, idled good, started good, didn't die at dropped throttle after a long hiway run & seemed to have a stable curb idle (the owner says it still runs great).



Do you know what actually is the difference in idle control between hexhead and camhead? It seems to me that the same procedure can work on the camhead also.

You did not mention anything about the TPS in this process. Did you have to relearn it at some point?

How do you actually verify fully closed throttle plate?

RPM up to just above the stepper link up By this you meant the point when the idle control is no longer in play?

How can you check whether initial TB throttle cam lift starts at same time? I can recognize when they reach back to the stop screws at same time, but lift at the same time? By verifying with the TB sync tool?


Sorry if I bother you with so much questions, but I'm pleased to finally discuss with someone who have been working on this challenging task and have something meaningful to say

#999277 - 10/19/17 11:06 AM Re: Possible way to adjust messed up TB stop screws [Re: 14TLC]  
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dirtrider Offline
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Morning 14TLC


Do you know what actually is the difference in idle control between hexhead and camhead? It seems to me that the same procedure can work on the camhead also.--No, I don't know ALL the differences, they are definitely close but I haven't ever compared them item for item.

You did not mention anything about the TPS in this process. Did you have to relearn it at some point?-- I didn't have to mess with the TPS on either hexhead that I did as neither one was messed with. As long as the TPS voltage is under the idle threshold voltage & not allowing dropped throttle fuel cut-off it shouldn't effect the idle balance or stepper position as the fueling system should be idling in closed loop (fueling based on o2 sensors not BMS-K mapping)

How do you actually verify fully closed throttle plate? -- I removed them & held up to a strong light then looked through while verifying the throttle plate was closed (I mainly did this to make darn sure than the throttle plates were centered & closing evenly.

"RPM up to just above the stepper link up" By this you meant the point when the idle control is no longer in play?-- At a certain point the steppers should quit being idle steppers then link to the same counts & follow the throttle open for a ways (I t-h-i-n-k) at this point they are being used a dash pot like device to prevent a quick dropped throttle engine stall.

How can you check whether initial TB throttle cam lift starts at same time? I can recognize when they reach back to the stop screws at same time, but lift at the same time? By verifying with the TB sync tool?
--I do it 2 ways, one is to hold a hand on each TB cable cam then have someone move the twist grip. I have also watched my manometer fluid column as it is very sensitive & will show even a slight TB side lead as I slightly open the twist grip. (basically used as a verification check, if the TB cams don't start their lift at the EXACT same time then there is something drastically wrong with TB balance or engine vacuum ability)


Sorry if I bother you with so much questions, but I'm pleased to finally discuss with someone who have been working on this challenging task and have something meaningful to say--It is a very challenging task as there is no BMW defined way of re-setting those base idle screws (BMW says to replace the TB's). A flow bench would be the best way but even then we would need to know the flow rate @ what pressure drop.

Another thing to keep in mind is: There is a system voltage monitor circuit inside the fueling computer that bumps the idle RPM up (adds stepper counts) if the voltage drops to a certain point (what that point is I don't know) so make sure the battery is good & fully charged before attempting to set/balance the steppers.

Another thing that I use is large "O" ring that fits tight on the handlebar end weight, I can roll that into the gap between the end of the twist grip & the bar end weight to allow the twist grip to stay in any position that I set it (basically a poor mans throttle lock)


D.R. ___
Sent from my rotory dial wall phone!
#999282 - 10/19/17 12:11 PM Re: Possible way to adjust messed up TB stop screws [Re: dirtrider]  
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14TLC Offline
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Hello dirtrider,

Do you know what actually is the difference in idle control between hexhead and camhead? It seems to me that the same procedure can work on the camhead also.--No, I don't know ALL the differences, they are definitely close but I haven't ever compared them item for item.

You did not mention anything about the TPS in this process. Did you have to relearn it at some point?-- I didn't have to mess with the TPS on either hexhead that I did as neither one was messed with. As long as the TPS voltage is under the idle threshold voltage & not allowing dropped throttle fuel cut-off it shouldn't effect the idle balance or stepper position as the fueling system should be idling in closed loop (fueling based on o2 sensors not BMS-K mapping)
Do you know the value of this idle threshold? Is it something that can be checked with GS-911?

How do you actually verify fully closed throttle plate? -- I removed them & held up to a strong light then looked through while verifying the throttle plate was closed (I mainly did this to make darn sure than the throttle plates were centered & closing evenly.
Basics. I really hoped you have some trick to spare me the time of doing that smile

"RPM up to just above the stepper link up" By this you meant the point when the idle control is no longer in play?-- At a certain point the steppers should quit being idle steppers then link to the same counts & follow the throttle open for a ways (I t-h-i-n-k) at this point they are being used a dash pot like device to prevent a quick dropped throttle engine stall.
Spot on for the dampening functionality. I can even see that in action. Just blip the throttle to 4.000-5.000 RPM and after release it is clearly perceptible that the RPM will hold for a brief moment around 1.800 RPM

How can you check whether initial TB throttle cam lift starts at same time? I can recognize when they reach back to the stop screws at same time, but lift at the same time? By verifying with the TB sync tool?
--I do it 2 ways, one is to hold a hand on each TB cable cam then have someone move the twist grip. I have also watched my manometer fluid column as it is very sensitive & will show even a slight TB side lead as I slightly open the twist grip. (basically used as a verification check, if the TB cams don't start their lift at the EXACT same time then there is something drastically wrong with TB balance or engine vacuum ability)


Sorry if I bother you with so much questions, but I'm pleased to finally discuss with someone who have been working on this challenging task and have something meaningful to say--It is a very challenging task as there is no BMW defined way of re-setting those base idle screws (BMW says to replace the TB's). A flow bench would be the best way but even then we would need to know the flow rate @ what pressure drop.

Another thing to keep in mind is: There is a system voltage monitor circuit inside the fueling computer that bumps the idle RPM up (adds stepper counts) if the voltage drops to a certain point (what that point is I don't know) so make sure the battery is good & fully charged before attempting to set/balance the steppers.

Another thing that I use is large "O" ring that fits tight on the handlebar end weight, I can roll that into the gap between the end of the twist grip & the bar end weight to allow the twist grip to stay in any position that I set it (basically a poor mans throttle lock)


[/quote]

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