R1200 Throttle Sync & Stepper Motors.....

[Redbrick]

Clarification on stepper motors please....When is it necessary to "park" them when doing a throttle sync? Or is it necessary at all?... Is it correct that the SM's set the sync at idle and that's their only function?...

 

In a learning cycle here ...

 

Thanks......

 

Phil...........Redbrick

[Ken H.]

When is it necessary to "park" them when doing a throttle sync? Or is it necessary at all?... Is it correct that the SM's set the sync at idle and that's their only function?...

It's a controversial subject...

 

I would maintain that they don't effect just idle sync. They do, indeed have to effect it at all RPM's. Because after all, they are air bypass ports into the intake system, they have to have an impact. Just like the Large Brass Screws of the oilheads. And they are how the bike adjust sync on the fly while riding.

 

So the goal of "parking" them in the same identical position on each side is to maximize the amount of future adjustment range they have.

 

Plus that's how the dealer's system does it, there must be a valid reason.

 

Unfortunately the aftermarket world hasn't figured out how to do it (heaven knows I've tried) but fortunately we can approximate it. When you turn the bike off they return to a fixed same position. We don't know if that it is the same position as the dealer's "parked" position when they do a sync, but we do know it is the same position side to side.

 

So what I advocate doing is disconnect them with the bike off. Then sync'ing it. The shut it back down and reconnect them.

 

Now almost certainly someone will jump in here and say they have sync'ed their hexhead with them connected and it was just fine. My take would be that if the available adjustment range of both steppers from their current running position is still adequate, then they indeed are likely just fine. But what if it isn't? Then you have a bike that may run a bit out of sync because the stepper(s) is at one extreme or the other of the total adjustment it can make.

 

Like I said, it's controversial.

[Redbrick]

Good explanation Ken....Will do a sync soon at about 18M miles but with my limited experience thus far, I don't think I'll mess with the SM's.....Jim's DVD doesn't mention them during the throttle sync section but I keep hearing about them so was curious....

I will use my new $8 manometer along with the TwinMax just to see how they compare....Interesting....

 

Thanks......

 

Phil...........Redbrick

[Ken H.]

Jim's DVD doesn't mention them during the throttle sync section

Yeah, Jim is in the other camp on this. Difference of opinion. He agrees with the correct side on most things most of the time.

 

Oh, Hi Jim!

[RoSPA_man]

When is it necessary to "park" them when doing a throttle sync? Or is it necessary at all?... Is it correct that the SM's set the sync at idle and that's their only function?...

It's a controversial subject...

 

I would maintain that they don't effect just idle sync. They do, indeed have to effect it at all RPM's. Because after all, they are air bypass ports into the intake system, they have to have an impact. Just like the Large Brass Screws of the oilheads. And they are how the bike adjust sync on the fly while riding.

 

So the goal of "parking" them in the same identical position on each side is to maximize the amount of future adjustment range they have.

 

Plus that's how the dealer's system does it, there must be a valid reason.

 

Unfortunately the aftermarket world hasn't figured out how to do it (heaven knows I've tried) but fortunately we can approximate it. When you turn the bike off they return to a fixed same position. We don't know if that it is the same position as the dealer's "parked" position when they do a sync, but we do know it is the same position side to side.

 

So what I advocate doing is disconnect them with the bike off. Then sync'ing it. The shut it back down and reconnect them.

 

Now almost certainly someone will jump in here and say they have sync'ed their hexhead with them connected and it was just fine. My take would be that if the available adjustment range of both steppers from their current running position is still adequate, then they indeed are likely just fine. But what if it isn't? Then you have a bike that may run a bit out of sync because the stepper(s) is at one extreme or the other of the total adjustment it can make.

 

Like I said, it's controversial.

 

This raises lots of questions

1. Are the steppers dynamic - ie do they set themselves or are they set by the dealer when synching and do they stay in whatever position that is?

2. I thought the stepper were for tickover adjustment. If tickover is lumpy and badly set, does that mean good synching above tickover - ie when the throttles are "on the cables" is more difficult/impossible to attain

3. If the stepper control tickover, then whether they are conncected ot taken out of play, will synching not be impossible to achieve?

4. Is there any source of information out there about what SMs do etc? This particular topic seems to be (unusually) opinion-led rather than fact-led

[Redbrick]

Sorry........

 

 

Phil.........Redbrick

[Jim VonBaden]

Jim's DVD doesn't mention them during the throttle sync section

Yeah, Jim is in the other camp on this. Difference of opinion. He agrees with the correct side on most things most of the time.

 

Oh, Hi Jim!

 

Hi Ken!

 

I'm still playing with the stepper motor idea. Maybe one day I will find an R1200 that is sufficienty out of whack that I can prove the theory one way or the other.

 

Jim

 

PS I still currently do not disconnect them, but see no harm in it.

[Ken H.]

This raises lots of questions

1. Are the steppers dynamic - ie do they set themselves or are they set by the dealer when synching and do they stay in whatever position that is?

2. I thought the stepper were for tickover adjustment. If tickover is lumpy and badly set, does that mean good synching above tickover - ie when the throttles are "on the cables" is more difficult/impossible to attain

3. If the stepper control tickover, then whether they are conncected ot taken out of play, will synching not be impossible to achieve?

4. Is there any source of information out there about what SMs do etc? This particular topic seems to be (unusually) opinion-led rather than fact-led

 

Well BMW doesn't tell us a lot, do they? Most of this is deduction by those of us who have been working with them for a couple of years now. I spent a bunch of time (and $$, having ruined one in the process) about a year ago trying to learn more about how they work. But to you specific questions, here's what I can say:

 

 

1. Are the steppers dynamic - ie do they set themselves or are they set by the dealer when synching and do they stay in whatever position that is?

 

They are clearly dynamic, changing their position as the BMS-K engine management module detects variations in sync that needs to be corrected.

 

2. I thought the stepper were for tickover adjustment. If tickover is lumpy and badly set, does that mean good synching above tickover - ie when the throttles are "on the cables" is more difficult/impossible to attain

 

The steppers are primarily for tickover (idle) sync, but as I mentioned above, by their very nature their setting has to also effect sync at higher RPMs, to at least some extent. If they are in a miss-matched state when as you say, "on the cables" ie, at above tickover/idle, I don't believe it makes it harder to do that sync. There is plenty of adjustment in the cables to overcome whatever position the steppers happen to be in. To me the bigger question is, what happens latter? Will the dynamically adjusting/changing steppers have enough remaining range of their own to make adjustments? If not centered/parked during the cable sync, I think in theory it is possible that they may not.

 

3. If the stepper control tickover, then whether they are conncected ot taken out of play, will synching not be impossible to achieve?

 

Not necessarily, again the cable has lots of adjustment. But what I have seen is while doing the cable adjustment with them connected, the sync seems to vary a lot, making finding the 'sweet spot' harder. I have a theory that this is the steppers trying to make adjustments at the same time you are. In particular given as we know that cable syncs are very touchy in general and it's easy to overshoot the opposite direction when making an adjustment. In effect I suspect the steppers and you are fighting each other. All the more reason to take them out of service when doing the cable adjustment IMHO.

 

4. Is there any source of information out there about what SMs do etc? This particular topic seems to be (unusually) opinion-led rather than fact-led

 

Not that I've seen. BMW is talking.

[RedMac]

Ken,

I'm about to do my 12K maint. Do you have a picture or anything about how to disconnect them to do the sync?

 

Thanks

Mike

[RoSPA_man]

This raises lots of questions

1. Are the steppers dynamic - ie do they set themselves or are they set by the dealer when synching and do they stay in whatever position that is?

2. I thought the stepper were for tickover adjustment. If tickover is lumpy and badly set, does that mean good synching above tickover - ie when the throttles are "on the cables" is more difficult/impossible to attain

3. If the stepper control tickover, then whether they are conncected ot taken out of play, will synching not be impossible to achieve?

4. Is there any source of information out there about what SMs do etc? This particular topic seems to be (unusually) opinion-led rather than fact-led

 

Well BMW doesn't tell us a lot, do they? Most of this is deduction by those of us who have been working with them for a couple of years now. I spent a bunch of time (and $$, having ruined one in the process) about a year ago trying to learn more about how they work. But to you specific questions, here's what I can say:

 

 

1. Are the steppers dynamic - ie do they set themselves or are they set by the dealer when synching and do they stay in whatever position that is?

 

They are clearly dynamic, changing their position as the BMS-K engine management module detects variations in sync that needs to be corrected.

 

2. I thought the stepper were for tickover adjustment. If tickover is lumpy and badly set, does that mean good synching above tickover - ie when the throttles are "on the cables" is more difficult/impossible to attain

 

The steppers are primarily for tickover (idle) sync, but as I mentioned above, by their very nature their setting has to also effect sync at higher RPMs, to at least some extent. If they are in a miss-matched state when as you say, "on the cables" ie, at above tickover/idle, I don't believe it makes it harder to do that sync. There is plenty of adjustment in the cables to overcome whatever position the steppers happen to be in. To me the bigger question is, what happens latter? Will the dynamically adjusting/changing steppers have enough remaining range of their own to make adjustments? If not centered/parked during the cable sync, I think in theory it is possible that they may not.

 

3. If the stepper control tickover, then whether they are conncected ot taken out of play, will synching not be impossible to achieve?

 

Not necessarily, again the cable has lots of adjustment. But what I have seen is while doing the cable adjustment with them connected, the sync seems to vary a lot, making finding the 'sweet spot' harder. I have a theory that this is the steppers trying to make adjustments at the same time you are. In particular given as we know that cable syncs are very touchy in general and it's easy to overshoot the opposite direction when making an adjustment. In effect I suspect the steppers and you are fighting each other. All the more reason to take them out of service when doing the cable adjustment IMHO.

 

4. Is there any source of information out there about what SMs do etc? This particular topic seems to be (unusually) opinion-led rather than fact-led

 

Not that I've seen. BMW is talking.

 

So let me summarise what I think we know collectively

 

1. SMs are used to set the tickover by some unknown process used by the dealer.

 

2. The cables are out of the equation completely at tickover. Therefore the SMs are set/set them selves to a particular position in each throttle body, mimicking what used to be done by the brass screws on the 1150

 

3. The additional job of the SMs is to adjust themseles dynamically to compensate for any detected lack of sync when the bike is "on the cables"

 

4. When you stop and the bike is ticking over again, the SMs revert to the exact setting achieved in 1) above by the dealer. This setting may, or may not, have each SM at the exact same setting.

 

4. With Sms disconnected, we balance the throttles so that they are equal at some/all RPMs. The SMs then cut in to correct any minor differences that are detected.

 

I assume the tickover is controlled by a different jet than the main cable operation?

[Ken H.]

Do you have a picture or anything about how to disconnect them to do the sync?

Just disconnect the electrical connector to each one before starting the bike:

 

[Ken H.]

So let me summarise what I think we know collectively

 

Well close...

 

1. SMs are used to set the tickover by some unknown process used by the dealer.

 

Tickover/idle speed and sync are controlled exclusively by the BMS-K computer. The dealer has no control over either.

 

2. The cables are out of the equation completely at tickover. Therefore the SMs are set/set them selves to a particular position in each throttle body, mimicking what used to be done by the brass screws on the 1150

 

Yes

 

3. The additional job of the SMs is to adjust themseles dynamically to compensate for any detected lack of sync when the bike is "on the cables"

 

Yes

 

4. When you stop and the bike is ticking over again, the SMs revert to the exact setting achieved in 1) above by the dealer. This setting may, or may not, have each SM at the exact same setting.

 

No, I don't believe with the bike back at tickover/idle they go back to a fixed position. Rather I think they stay at where they last obtained best sync. However when you shut the bike down they definitely go back to the same position. This I have verified by taking them out and measuring the position of the plunger. They are identical side-to-side after shut down.

 

I tried disconnecting them while the bike was running to then shut it down, remove them and measure them, but it was inconclusive.

 

 

4. With Sms disconnected, we balance the throttles so that they are equal at some/all RPMs. The SMs then cut in to correct any minor differences that are detected.

 

Yes

 

 

I assume the tickover is controlled by a different jet than the main cable operation?

It's definitely not a different jet. There is only one fuel injector on each side. Rather I believe it used an adjustment of stepper position, fuel injector rate, and ignition timing.

[Don_Eilenberger]

So let me summarise what I think we know collectively

 

1. SMs are used to set the tickover by some unknown process used by the dealer.

Questionable assumption. I would assume (my assumption) that idle speed (tickover) is set by software code in the engine control module - from the factory. There is no reason for a dealer to be able to change the setting the factory determined is optimal. The actual opening (and closing) of the steppers is used to change idle speed - and perhaps - idle TB balance.

2. The cables are out of the equation completely at tickover. Therefore the SMs are set/set them selves to a particular position in each throttle body, mimicking what used to be done by the brass screws on the 1150

I think this is a reasonable assumption.

3. The additional job of the SMs is to adjust themseles dynamically to compensate for any detected lack of sync when the bike is "on the cables"

Questionable assumption - small hole GREAT BIG HOLE.. The actual air passage of the steppers is probably the same as the big-brass-screws were - and it is really insignificant in comparison to even a partly opened throttle plate. I rather doubt if they have any correcting feature for thottle cable sync.

4. When you stop and the bike is ticking over again, the SMs revert to the exact setting achieved in 1) above by the dealer. This setting may, or may not, have each SM at the exact same setting.

I'm perhaps confused in what you're saying. It appears you believe the steppers are set to some arbitrary position by the dealer using their GT1. I think this is wrong - wouldn't be any need for them if that was their function - the big-brass-screw performed that function just fine.

 

The steppers (as I understand their operation) are dynamically controlled by the engine control unit to maintain a certain idle speed set in the ECU. This idle speed may change according to inputs such as engine temperature - to the ECU. If the engine is cold - they open further to maintain a "fast idle" - such as what we had with the "choke" lever on oilhead bikes (and on K bikes.)

 

They may or may not (not a lot of info available on this, and I'm wondering about the detection mechanism) also do some balance of the air-flow through the TBs at idle, when the throttle plates are not open.

4. With Sms disconnected, we balance the throttles so that they are equal at some/all RPMs. The SMs then cut in to correct any minor differences that are detected.

 

I assume the tickover is controlled by a different jet than the main cable operation?

It's not a "jet" - I think you have to look at how the throttle body works and what it does.

 

Simplified explaination: The TBs control airflow to the engine. The changing airflow controls the speed of the engine. The user changeable portion is controlled by the throttle-plate which is connected to a cable that eventually connects to the fun-grip (right side..)

 

The idle (tickover) function is an air passage that goes around (bypass circuit) the throttle plate. It is controlled on these TB's by the stepper motors - which change the volume of air going through the bypass circuit in response to the ECU.

 

As far as the steppers correcting any imbalance between the throttle bodies when under cable control - to me this is questionable due to the "small hole BIG HOLE" problem. The amount of air that can flow through the small bypass circuit is a very small proportion of the air that can flow past a fully open throttle plate.

 

Is this any clearer or did I just make fudge out of it?

[RoSPA_man]

Thanks guys for the explanations. It's a complicated tpoic so let's split it and first let's talk about tickover

 

Tickover - if that is uneven or not smooth and nicely settled or too high RPM as examples, what remedies does a dealer with his box of tricks have? If the SMs are factory set, are they set when produced or when on a specifice engine? It seems SMs can't be adjusted - if so, ,what other adjustment is there on the TBs to regulate tickover?

[Ken H.]

what other adjustment is there on the TBs to regulate tickover?

There are none. The tickover/idle is controlled completely by the BMS-K engine management computer.

 

If the bike is not idling correctly, that says something is broken/failed. The dealer can troubleshoot various systems to try to determine what needs to be replaced to correct the issue, but there is no adjustment they can make specifically to change tickover/idle.

[RoSPA_man]

what other adjustment is there on the TBs to regulate tickover?

There are none. The tickover/idle is controlled completely by the BMS-K engine management computer.

 

If the bike is not idling correctly, that says something is broken/failed. The dealer can troubleshoot various systems to try to determine what needs to be replaced to correct the issue, but there is no adjustment they can make specifically to change tickover/idle.

 

So the BMS-K controls tickover and there is no means of effecting any adjustment? That being the case, what else could affect tickover - I guess valves clearances is one.. are there others?

 

Also, if the SMs adjust the sync on the fly, then accurate synching is logically not as critical as say on the 1150s (of course assuming that the SMs have enough range to make that adjustment etc...

 

Finally, after my last sync at the dealers, I though that the transition from tickover to "on the cables" was not as seamless as it had been - any thoughts?

[Redbrick]

.........................

Finally, after my last sync at the dealers, I though that the transition from tickover to "on the cables" was not as seamless as it had been - any thoughts?

 

My 1200 throttle response is not as "seamless" as Kathy's 1150....I'm interested how it will be after I sync it myself...Has been done by the dealer up 'til now....

 

Phil.......Redbrick

[RoSPA_man]

.........................

I'm interested how it will be after I sync it myself...Has been done by the dealer up 'til now....

 

Phil.......Redbrick

 

Which method are you going to go with Phil - SMs connected or disconnected? I wonder what method, if any, the Haynes manual recommends?

[Jim VonBaden]

Don, it definitely seems you have a decent grasp of the stepper motor situation and operation. Excellent answers.

 

You guys make me feel a bit slow describing things at times. Thank doG for video, it allows me those 1000 words extra!

 

Jim

[Redbrick]

.........................

I'm interested how it will be after I sync it myself...Has been done by the dealer up 'til now....

 

Phil.......Redbrick

 

Which method are you going to go with Phil - SMs connected or disconnected? I wonder what method, if any, the Haynes manual recommends?

 

After the knowledge from this thread I will unplug the steppers while syncing and have a Haynes manual on the way which I'll check out regarging this....See the thread in "Bike Related........"...The Haynes in now available here and a lot cheaper than from Blighty (Nippy Norman's)......

 

 

Phil........Redbrick

[RoSPA_man]

Thanks Don - excellent replies - all makes sense - what I want to do, to tease this further, is to try to summarise the whole system so we can find at least the facts that everyone seems to agree on. Thanks once again

[Ken H.]

though that the transition from tickover to "on the cables" was not as seamless as it had been - any thoughts?

Have you gone through the throttle position sensor (TPS) re-train procedure? Some versions of the BMS-K software were more sensitive to off idle transition than others, and the re-training seems to help on some of them.

[RoSPA_man]

though that the transition from tickover to "on the cables" was not as seamless as it had been - any thoughts?

Have you gone through the throttle position sensor (TPS) re-train procedure? Some versions of the BMS-K software were more sensitive to off idle transition than others, and the re-training seems to help on some of them.

 

I had forgotten that procedure! Is it two complete open and closes of the throttle with ignition on, engine off?

[Emoto]

though that the transition from tickover to "on the cables" was not as seamless as it had been - any thoughts?

Have you gone through the throttle position sensor (TPS) re-train procedure? Some versions of the BMS-K software were more sensitive to off idle transition than others, and the re-training seems to help on some of them.

 

I had forgotten that procedure! Is it two complete open and closes of the throttle with ignition on, engine off?

 

Yes.

[Jim VonBaden]

.........................

I'm interested how it will be after I sync it myself...Has been done by the dealer up 'til now....

 

Phil.......Redbrick

 

Which method are you going to go with Phil - SMs connected or disconnected? I wonder what method, if any, the Haynes manual recommends?

 

I am willing to bet the Haynes manual will simply tell you to take it to the dealer because you need the GT1 to do it.

 

Jim

[Sliver]

Please explain the TPS retrain procedure. I've been having issues with my idle since I got the 6K service on my R12ST. The dealer keeps telling me that it's OK....

[Ken H.]

Please explain the TPS retrain procedure. I've been having issues with my idle since I got the 6K service on my R12ST. The dealer keeps telling me that it's OK....

Turn the key on with the bike start-able (kill switch in run, bike in neutral) but don't start it.

 

Rotate the throttle through its entire range twice.

 

Now start the bike.

 

 

BTW, it's in your owners manual under battery replacement.

[Sliver]

Thanks. I did this same procedure on my 1150, but only after disconnecting the battery or pulling the ecm fuse.

 

Just to be clear, on the R1200, I can do the TPS retrain without first disconnecting power???

Sorry for being tedious

[Ken H.]

Just to be clear, on the R1200, I can do the TPS retrain without first disconnecting power???

Yes. On the R1150 series too for that matter.