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Mike T

Throttle Body Sync using GS-911

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Mike T

I've read through a few posts on the GS-911 and syncing the throttle bodies. Some of these posts were a work in process on trying various things. For folks that use the GS-911 what is your latest view on the proper technique for syncing the throttle bodies. I have the latest version of the GS-911 and a Twinmax.

 

Thanks in advance.

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CoarsegoldKid

I have no idea is what I did was proper or not but this is what I did. Heck brought over his GS911 and hooked it up. He told it to set the stepper motors to zero. The motors could be heard turning and such. I set up my mercury manometer on the nozzles on the TBs and started the engine which was previously warmed. Then I adjusted the # 1 cycl(right side) TB cable screw until the mercury columns were level.

If you have a standard 10mm open end wrench you may need to grind off some material to make it thin as there may not be much room between the locking nut and the adjusting nut. Two 10mm wrenches are needed to secure the adjustment.

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Ken H.

1) Follow the step-by-step instructions in the GS-911 software to park the steppers. The software won't let you park the steppers and proceed until the engine is to the proper operating temp to do the sync.

 

2) Adjust the right side cable to being in-sync at something above idle.

 

3) Follow the step-by-step instructions in the GS-911 software to finish.

 

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RedMac

Ken,

Do you really need the GS-911 to properly sync the TBs? Does it need to be done at idle?

 

From reading previous posts, I just use a Twinmax and just ignore the idle setting (it's always off by a bit) and sync using the RH cable at higher revs. Once I set it at say 3K, I find it's pretty good at anything but idle.

 

I assume I'm doing this correctly?

 

Thanks

Mike

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Ken H.
Ken,

Do you really need the GS-911 to properly sync the TBs? Does it need to be done at idle?

 

From reading previous posts, I just use a Twinmax and just ignore the idle setting (it's always off by a bit) and sync using the RH cable at higher revs. Once I set it at say 3K, I find it's pretty good at anything but idle.

Before the GS-911 added the feature of locking the steppers in a fixed position for doing a sync, the majority of us where taking just that approach (although a few of us have experimented with disconnecting them before doing a sync) - ignore the idle and adjust the right side cable for best sync above idle. And that approach seemed to by-and-large work just fine. So if you are happy with the results you certainly can continue to do just that.

 

That being said, since the “parking” feature was added, and after following it on three hexheads I have uses it on, I’d have to say (for reasons that aren’t entirely clear, even to the HEXCode team) the bikes did seem to be smoother than with the old non-parking steppers method.

 

I think we just don’t know full functionality of the BMS-K module and its control of the injectors and steppers. So for now, I’m betting on following OEM procedure (which the GS-911 invokes) of parking the steppers prior to a sync. YMMV.

 

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Marty Hill

Mike, you fine doing it your way. I use 3.5 to 4k tho.

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RoadJunkie

If I owned, or had access to the GS-911 I would take full advantage of all the features, including TBS support. But since I don't, I will live with the TwinMax, no park, method. I would like to try the GS-911 method once to see if any difference could be detected.

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Heck

I have the gs911 and have only used it for reading fault codes up to this point, I guess it would be handy to use the above method to do the sync. I have been told that 2007 and later must use a different method. Don't know what that would be. Any comments?

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Ken H.
I have been told that 2007 and later must use a different method. Don't know what that would be.

Neither do I, the TB setup has been consistent throughout the hexhead series. Sure you’re not thinking about the change made in braking systems?

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Mike T

Here's an update on the throttle body sync. 2006 RT with 18K miles. Once I realized that I had to download the Beta release software from the GS-911 website to find the instructions on parking the stepper motors, everything went very smoothly.

 

Prior to adjusting the TB's I used the calibrate steppers function that helps smooth out idle.

 

I then went through the procedure on TB calibration using the GS-911 Beta software. Easy to follow step by step instructions. Using a Twinmax the balance was off very, very slightly as max sensitivity (the needle was just right of center and less than half way to the fist measurement mark on the twinmax) at 2K to 4K RPMs. It was so close to center I almost decided not to mess with it but did so anyway. Got the needle right at center with very minor adjustment.

 

Took the bike for a test ride and was amazed at how smooth the bike rode. It seemed that I had to use much less throttle then before and the bike seemed quieter. I've adjusted the TBs before and they were always close and the adjustment never seemed to make much difference. This is the best the bike has run in the 3 years that I've owned it.

 

I'm wondering if the act of calibrating or parking the stepper motors is what improved the performance vs the minor cable adjustment I made.

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KDeline

ignore the idle and adjust the right side cable for best sync above idle.

 

Why does the right side seem to be the one to adjust?

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SWB

Well, I just did my first R1200RT sync (as compared to my old R1100RT). I more or less followed the a "modified Von Baden", i.e. without the GS-911 because I'm too cheap to buy one. ;) However, since this thread discussed TBS sync in general, I thought I'd toss my experience into the discussion.

 

  • Warmed up the bike to operating temps.
  • Pulled the plug and shutdown power for about 5 minutes.
  • Disconnected the stepper motors
  • Reconnected the battery, turned on the ignition (but didn't start the bike), opened the throttle full twice reset the computer and then powered down.
  • Hooked up the Twin max and calibrated - sensitivity on high. Set sensitivity to low.
  • Loosened the lock nuts on both throttle body cables.
  • Started engine. Backed off left screw and then tightened it until the Twinmax needle JUST started to move, then backed it out one turn. Did the same to the right side. Tighted the lock nut on the left side cable.
  • Engine ran ROUGH, as expected. Did my best to sync at idle. Shutdown engine. Hooked up the stepper motors.
  • Restarted the engine. Better at idle, and improved over time as the computer and steppers relearned their optimum position at idle and adjusted (presumably).
  • Worked on sync from 2K, 3K, 3500K, 4K, while adjusting the right throttle cable. Did it again. And again. More times. Needle moved "left" when I tightened, and "right" when I loosened. Couldn't get it to consistently stay on "zero" at 3500K. Throttle cable adjustment is VERY sensitive. Just a little bit of tension on the nut or cable changes sync a whole lot.
  • No matter how much I loosened the right side to pull the needle from left to center, it didn't seem to be enough. That's when I figured "heck, the left cable must be way too loose or too tight, because the right side isn't responding". So, I unlocked the nut on the left side and sure enough, after I tighted it a quarter turn and locked it, the right throttle screw was more responsive. I could adjust the needle left to right and center.
  • After more fiddling, I discerned a consistent pattern. Accelerating from 2K through 4K, the needle would move from left to right. I could sync it up at a given point, but it wouldn't "hold" sync throughout the throttle range.
  • I finally locked it in at 3500K, and that was "it" for today.
  • Finally, +1 to the guys saying find a very thin 10mm wrench for the lock nut. Was a real *** trying to get a wrench in there. I finally held the throttle cable nut "over the top" with a large pair of pliers while I used my "fat" 10mm to tighten the locknut. A REAL hassle since just the slightest movement of the cable adjusting nut messes with the sync in a very noticeable way. Need to find me one of those 10mm wrenches on a diet.

 

The bike runs strong, starts well, idles OK. However, I don't think it's quite to "spec". From experience with my old R1100RT, I'm pretty sure I have one or more problems with this 2005 RT with 48K miles on the odometer. When I reset the valves, I found one has a damaged lock nut (or valve stem bolt - whatever they call those thingys). That made setting clearance and getting it to "stick" on that intake valve difficult. Other than that, it was a very easy adjustment. I checked rocker arm shaft end clearance, which was anywhere from 0.10mm to 0.20mm, well within the 0.05mm to 0.40mm spec. (Wasn't happy with it, particularly because the variance was considerable from left to right on the same cylinder, but will wait to next tune up to reset it).

 

I'm guessing that either my valves aren't set exactly right, or I've got some sort of vacuum leak or other mechanical defect someplace. I handled this kind of situation on the R1100RT by replacing all "O" rings on the intake systems, de-coking the throttle bodies, replacing the throttle cable and bowden box, i.e. making sure everything on the intake was clean and tight. I'll probably do that next tuneup as well, AND fix the messed up valve adjuster if I can do it without major engine work.

 

Other than that, I don't know why the throttle balance would "pull" from left to right as the throttles both increased. They're obviously not pulling evenly or together, but it's not a real bad situation, i.e. less than half a notch left to just a bit to the right over about a 3K RPM range.

 

Maybe I'll have to sponsor a Tech Daze at my house for the Southern California riders; price of admission will be someone bringing out their GS-911. I'd love to compare the difference. :grin:

 

- Scott

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Peter Parts

My 2-cents.

 

Not helpful tuning no-load in your driveway. You are "tuning" only the first 1/8 inch of throttle (or coupla degrees of butterfly) and the map cell for no-load for say, "4000 rpm at 3 degrees open" is wonkee if not entirely undefined on the ECU map.

 

While a vacuum gauge is a bit more sensitive than a TwinMax (you read it here first), you may be interpreting tiny changes which vary with the weather and all at near-idle butterfly angles. And you can eliminate some of low-throttle imbalance with a TB to TB cross-over - automatically and forever.

 

TwinMax gives you only non-scaled relative values while dual vacuum gauges give you relative and absolute.

 

Go riding with dual vacuum gauges.

Edited by Peter Parts

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Ken H.
Why does the right side seem to be the one to adjust?

You’re trying to get a tracking match between the two, there’s no point in adjusting the left one, you just end up chasing your tail. ISFA why the right side, I suspect it has to do with tradition as much as anything, going all the way back to the 1100 series where position of the TPS on the left side at idle was critical. The approach has continued to this day, if for no other reason that constancy in procedures from model to model.

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CoarsegoldKid

Speaking of using the GS911. When I used it we watched the lambda air sensor graphs and they looked a bit wild. Are they supposed to track each other? What are they supposed to look like? One had sort of a saw tooth and the other had flattened peaks. However the engine performs well.

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KDeline
Why does the right side seem to be the one to adjust?

You’re trying to get a tracking match between the two, there’s no point in adjusting the left one, you just end up chasing your tail. ISFA why the right side, I suspect it has to do with tradition as much as anything, going all the way back to the 1100 series where position of the TPS on the left side at idle was critical. The approach has continued to this day, if for no other reason that constancy in procedures from model to model.

 

O.K. that is what I thought I read sometime ago, probably on this site. I only set one cable to the other, aways the right, after checking the free play on the left.

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Jim VonBaden
Why does the right side seem to be the one to adjust?

You’re trying to get a tracking match between the two, there’s no point in adjusting the left one, you just end up chasing your tail. ISFA why the right side, I suspect it has to do with tradition as much as anything, going all the way back to the 1100 series where position of the TPS on the left side at idle was critical. The approach has continued to this day, if for no other reason that constancy in procedures from model to model.

 

AND, the right side is easier to get to to adjust. That, and if you never mess with the left side, you wont tend to reduce the slack, so it wont need adjusting.

 

To the OP, if your sync keeps wandering as your engine speed changes, you likely have a vacuum leak. Possibly in your intake boots.

 

Jim :Cool:

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Don_Eilenberger

Mike,

 

Been discussing this with Stephen (Mr GS911) quite a bit, and swapping log files and screen captures.

 

What we have found - some hexheads - the stepper motor positions will vary at idle (one open more than the other.) This appears to be dynamic - they change on the order of 30 second or so intervals. We do not know what triggers the changes. (Edit: I should note - if I disconnect one of the vacuum lines to a TB - there will be a reaction on the part of the stepper positions - so something is sensing what the engine is doing in real-time.)

 

Above idle - the stepper motors seem to lock-sync in STEPS. If the step count is out (which is entirely possible since there is no feedback from the steppers to the ECU and they can drop counts) - what shows as being the same opening might be different openings in reality.

 

The stepper zero-adjustment assumably puts the stepper motors back in sync by fully closing them and then zero'ing out each sides step counter. IF your steppers had lost steps - even when the ECU thought they were both open the same amount, they might not be, and if so - you've now "balanced" the TB's to compensate.

 

Ideally - you want to use the GS-911 or an equivelent, that before allowing you to do the balance first zero's the steppers, then locks them at a set open position.

 

I believe the calibration of the steppers combined with an accurate TB sync is what improved the performance for you.

Edited by Don_Eilenberger

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graydude

I have not been this confused since that night in college..er...sorry, wrong forum. Steppers, GS0911, what the hell!! Can the average shade tree mechanic adjust the TB's or not?? Are these extra steps in the procedure really necessary are will they simply go from 90% acceptable to 98% acceptable? I'm ready to swap in a Briggs and Stratton and be done with it.

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Mike T

Thanks for the input Don. I think your explanation on the GS911 syncing the stepper motors makes sense. I used to balance the TBs without the GS911(and without disconnecting the stepper motors) and did not see much difference in performance even if the TB's needed some adjusting at off idle. It was almost like the stepper motors would compensate for the adjustment I was making in the cable thus keeping the balance (and performance) the same as before adjusting. I could be way off base here but that's what it seemed like.

 

After using the GS911 to zero (sync) the stepper motors the bike runs smoother (although I did not consider it not smooth before) and requires much less throttle to get moving.

 

Thanks again for all the input.

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Don_Eilenberger

Mike,

 

Glad it was helpful. I should point out that the effect of mis-matched steppers becomes smaller as the throttle opening becomes larger. Small hole vs large hole sort of thing - the percentage of air flowing through the small bypass passage via the steppers is small when compared to the large amount passing through the butterfly when the throttles are opened.

 

So to also answer the other poster - that's the 90% vs 98% part of the equation. I think you'll get close to 90% perfect without the GS-911. To get the last 10%.. well, I find the GS-911 worthwhile for other reasons also.

 

And I suspect you'd be awfully disappointed with the performance with a Briggs and Straton... :)

 

And I'll add - I am sometimes surprised how roughly my R12R idles - it can idle rough enough that if I have it in neutral with the clutch engaged, I can hear gearbox gear rattle. And that is with a good valve adjust and good TB sync. I think it's the nature of the beast, and I don't sweat it since it runs so sweet off-idle.

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Ken H.
I have not been this confused since that night in college..er...sorry, wrong forum. Steppers, GS0911, what the hell!! Can the average shade tree mechanic adjust the TB's or not?? Are these extra steps in the procedure really necessary are will they simply go from 90% acceptable to 98% acceptable?

“Average shade tree mechanic” is a bit of an ambiguous term, but yes, you can still do a basic TB sync yourself. Ignore the steppers and idle sync and adjust the right side cable to in sync at some RPM above idle. As Don said, that will get you into the 90 percentile. If you want better, you have to have better tools. Nothing new about that part.

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Jim VonBaden
I have not been this confused since that night in college..er...sorry, wrong forum. Steppers, GS0911, what the hell!! Can the average shade tree mechanic adjust the TB's or not?? Are these extra steps in the procedure really necessary are will they simply go from 90% acceptable to 98% acceptable? I'm ready to swap in a Briggs and Stratton and be done with it.

 

In general, you can get 90% without the GS-911, unless your cables do not have adequate slack, or your stepper motors are way off. Usually not the case.

 

Jim :Cool:

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Marty Hill

I have done my 12GS's at least 25 times and friends another 10 times...without the GS-911. They run perfectly. If it was necessary I'd have one and a second as a spare. Get my drift?

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Don_Eilenberger
I have done my 12GS's at least 25 times and friends another 10 times...without the GS-911. They run perfectly. If it was necessary I'd have one and a second as a spare. Get my drift?
Marty - how many miles on the GS's?

 

Reason I ask - I have never had to sync my TB's once the valves were adjusted correctly. This is on a low mileage bike - only about 34k on it so far, but it was surprisingly pleasant to find that BMW seems to have gotten the junction box and cable routing correct on this one. As far as running "perfectly" - I'm sure they feel wonderful, but have you done an A:B comparison (with and without a GS-911?)? (or your spare GS-911)? Get my drift?

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Ken H.

I hear what you are saying Marty, and prior to HexCo adding to the GS-911 the “zero steppers” function and the park/lock them function prior to doing a sync, I too thought our R1200GS and several other R1200XXs I worked on ran perfectly.

 

Then I did it the newest way with the GS-911.

 

It does make a definite, discernable improvement. Both at idle and at speed.

 

Get one and try it. You will be surprised!

 

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Marty Hill

To answer Don's ? I have over 160k miles on 6 12 GS's.

 

You guys love your GS-thingies...Wonderful/necessary, come on! :rofl:

 

Have mine been 100% perfect...to me yes. :thumbsup:

 

Am I wrong by 10%? Perhaps, but let's not make it seem like everyone needs one. Between this thread and one at ADV, some guys are thinking they can't service there bikes correctly.

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lawnchairboy

Would love to see iPhone compatible interface

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Jim VonBaden
Would love to see iPhone compatible interface

 

Won't happen. Too much effort for the small payoff, plus iPhone is not that easy to work with according to Stephan.

 

Marty,

 

I agree with you, mostly not necesary to have the GS-911 for TB sync. I also agree with Don, you rarely ever have to actually make an adjustment.

 

Jim :Cool:

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Don_Eilenberger

I think the real value of the GS-911 is zeroing out the steppers/bypass-passage. Stepper motors can lose "clicks" (steps). Expensive lab/cad-cam use ones have a tone-wheel and an optical sensor on the rear that work in a feedback loop to the driver stage, letting it know if it lost a step, and then the software for the driver will correct the lost step.

 

It appears our steppers are much simpler - and they "assume" they are in the right spot. Once they drift out of calibration, they are going to be open different amounts even when above idle (although they'll indicate they are in sync by "count".) That could lead to adjusting the TB cable sync to correct for the out of sync condition of the steppers. Not a desired way to do it.

 

If BMW was smart - they would have added a stepper reset into the ECU that was activated whenever the engine was turned off (perhaps after running XX time.) Instead, the stepper reset needs an outside trigger command which can be done by the GT1 or the GS-911.

 

Does the reset need to be done every time? Dunno. People have reported an improved idle quality after doing the reset. How long since the last reset would be interesting to know. The fact that my TB balance off-idle has always looked pretty much spot on after doing the valve adjustment leads me to believe (1) the steppers don't loose too many counts (2) the big-hole/small-hole relationship of the bypass and the TB butterfly opening makes the small imbalance even less significant. Enough that I'm pretty confident it gets the level of accuracy > 90%.

 

What is interesting - in a BMW instruction set I saw on balancing the TB's - they made note that after doing the stepper reset, and after locking the TBs for sync, to make note of the vacuum offset at idle of the steppers - and set the balance above idle (cable adjustment) to INCLUDE that same offset at all speeds.

 

How significant is that? Dunno - gonna have to try it in about 2,500 miles for the 36,000 mile service.

 

My feeling is - is a GS-911 absolutely needed to do a TB sync? Prolly not, but you might get a better sync if the stepper counts were zero'd out somehow.

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smiller
What is interesting - in a BMW instruction set I saw on balancing the TB's - they made note that after doing the stepper reset, and after locking the TBs for sync, to make note of the vacuum offset at idle of the steppers - and set the balance above idle (cable adjustment) to INCLUDE that same offset at all speeds.

That is interesting. I believe that on the hexheads there are no manual air bypass balance screws and the steppers are the only adjustment? If so and there's an imbalance left after zeroing the steppers I guess you could make a case for maintaining an equal delta throughout the throttle range, but I think you could also support a position that it's best to eliminate the differential as soon as you can (i.e. ignore it at idle but correct it at higher speeds.) I don't know which is correct (I would have thought the latter) but BMW's position is intriguing.

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Ken H.
You guys love your GS-thingies...Wonderful/necessary, come on! :rofl:

 

Have mine been 100% perfect...to me yes. :thumbsup:

 

Am I wrong by 10%? Perhaps, but let's not make it seem like everyone needs one. Between this thread and one at ADV, some guys are thinking they can't service there bikes correctly.

Marty, Marty my friend... nobody (at least not Jim, Don, me, others) ever said you had to have one to service your bike. As a matter of fact I’ve gone to great lengths in this (and other threads) to point out you/anyone can service the bike without a GS-911.

 

My only (and key) point is that IMHO you can do a better job of servicing a current gen BMW bike with better tools and the GS-911 is a better tool. And not just doing TB syncs, the ability to read trouble codes, run some diagnostics and more are key advantages of the GS-911 too. (Full disclosure – I have no interest in this tool or the company, only am a fan.)

 

No serious personal mechanic would work on cages these days without an ODB-II scanner, bikes are (quickly becoming) no different.

 

I’m sure ratchet wrenches were pooh-poohed as silly “thingies” when they first came out! But yah got to keep up with the times and I’ve got one of those too!

 

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aggieengineer

The only justification needed for buying the GS-911 is wanting one. Let's remember that this is a hobby for most if not all of us. And if we weren't interested in working on our own machines, we wouldn't be reading this forum. I think it's great that we still have people who take pride in trying to do the best possible job at any task. It's better yet when those people are willing to share their hard-earned expertise with other hobbyists. You guys know who you are, and my hat is off to you. Satisfaction is its own reward. -Another happy GS-911 owner.

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mecal

Has anyone had a stepping motor out of the bike?

I ask because I had a situation that after troubleshooting I found the right stepper was not working.

After removing the stepper, I found that the piston had unscrewed from the stepper motor. In this condition the stepper had backed up all the way, unable to adjust the plunger.

 

I screwed it back in, and checked that the motor still worked by turning the ign. on with the stepper in my hand. It did what looked like a reset movement. It went to full retract, full extend, then retract some, all in about 1 sec.

 

After TBS and test ride, checked TBS again, was way off.

Did TBS gain, test ride, again off, but only half as much.

Did TBS, test rides 4 more times, now no adjustment was necessary.

 

Now the question.

Do you think the stepper has reset itself, or is there more to do?

 

This could be a real world use for the GS-911.

 

The bike starts, runs very good, BUT has a rpm drop JUST, I mean just off idle. I have to use two hands on the throttle to bring up slow enough to notice it.

 

I am a retired test engineer, so loose ends drive me nuts.

Any thoughts?

 

 

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T__

mecal, you can’t judge much on a stepper motor when tested in your hand.. While it can fully retract OK when it goes into extension it will just go to the full count that is given it (usually just under the fully unscrewed point).. The Stepper has to be in it’s bore as then the extension will end at pintle fully seated..

 

Unless you used the GS-911 to do a stepper re-set after you re-installed it it probably took a while to become un-lost & re-acclimate itself to pintle position from seated..

 

Unless the threads in the stepper are actually stripped those things seldom cause problems..

 

Don’t know what to tell you on the RPM drop “just” off idle but some of the early 1200 heaxheads seem to exhibit that (especially cold).. Most people ride through it so fast it doesn’t seem to be a common complaint..

 

You might want check to be sure your 02 heaters are getting power (could be an 02 cooling off at idle) & check both TPS sensors for clean tracking & no output dips & sags..

 

You might also disconnects the battery for a few minutes to kill the TPS & stepper long term memory then do a key on TPS re-learn..

 

Do you have all the fueling computer updates in your bike?

 

 

Twisty

 

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NewBlue

First I would just like to say hello to all. Great site

Now for the question.

I have performed the TB sync using the GS911 and Twinmax

No problems but I was curious what exactly is being adjusted with the cables. From what I understand there must be 1mm of play in each cable, if the "do not touch screws" are the throttle stops and play remains in the cables what is being adjusted. If the cable is adjusting the throttle plate how can it do this and still have play?

 

Thanks for any input.

Edited by NewBlue

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T__
First I would just like to say hello to all. Great site

Now for the question.

I have performed the TB sync using the GS911 and Twinmax

No problems but I was curious what exactly is being adjusted with the cables. From what I understand there must be 1mm of play in each cable, if the "do not touch screws" are the throttle stops and play remains in the cables what is being adjusted. If the cable is adjusting the throttle plate how can it do this and still have play?

 

Thanks for any input.

 

NewBlue, welcome to the board..

 

The cable adjustment sets the CROSS SIDE throttle plate balance ABOVE IDLE..

 

At idle the plates are on the stops so the stepper motors control the side to side balance there.. Once the throttle is opened a little the cable slack is gone & the throttle plates are held in position by the throttle cables so any change in cable adjustment length changes the cross side balance..

 

Twisty

 

 

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NewBlue

Thanks Twisty,

I adjusted mine at idle but checked the sync at different RPM's and the sync was right on.

Should I be adjusting the cable off idle, say 2000 RPM's then checking to be sure there is play at idle?

 

When I did the sync I pulled on the cables and watched the meter, the left side was high so rather then tighten the right I loosened the left. Noted in the thread the right side seems to be the one to adjust so I hope loosening the left was acceptable.

Edited by NewBlue

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T__

NewBlue, there is nothing to adjust while at idle as the fueling computer handles the idle through the stepper motors.. You can check it at idle but there is nothing to change there..

 

You need to check & set the balance at well above idle once the slack it out of the cables & the throttle plates are off the idle stops..

 

2,000 RPM’s & 3,000 RPM’s is a good place to do it & even 4,000 if you want..

 

 

Twisty

 

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NewBlue

Thinking back, this was before I packed the bike in ice for the winter, pretty sure I checked and adjusted while at 2000. Did also check at 3000 and 4000

 

Thanks again

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mecal

twisty1

I will disconnect the battery and do throttle open closed reset.

I noticed today the rpm drop off idle is gone. Maybe temp. related?

Gets better each ride.

 

I had computer updates last Sept. with fuel sensor replacement. Bike is early 06 1200rt.

 

To make sure I understand.

The silver seating piston that screws into the stepper motor isn't supposed to screw in and out by itself right? The left silver piston was screwed all the way in, and right one was screwed out so far that when I first removed the right stepper from the bike it fell out, or should I say shot across the room.

 

The silver piston has slots the length of the threads, not sure what for.

 

Sorry I am not making this clear.

I thought the silver piston is screwed into the motor piston all the way, and stays there. All up and down motion is from the stepper main piston.

I didn't see any turning action while in my hand, or did you mean internal motor screw motion?

 

 

 

 

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T__

mecal, the piston (pintle) isn’t supposed to screw in & out on it’s own.. That slot in the threads is supposed to keep the pintle from spinning (it is sort of keyed internally) so as the stepper motor steps the pintle in & out the motor threads can screw the pintle in & out without the pintle spinning with it..

 

I haven’t ever tried on the BMW hexhead stepper motor but on most similar steppers you can sort of wiggle the pintel up & down & around a little & get it to work back into the stepper housing as the threads are not real tight fitting..

 

With the pintle retracted you shouldn’t be able to rotate (screw) the pintle in the housing.. If you can it sounds like maybe a problem internally with the locating key (check it against the other side as a comparison)

 

 

Twisty

 

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mecal

The next time I have the bike apart, I will pull both steppers and compare them.

I think all is working properly because with a water manometer, idle to 5k only moves 1.5". That 1.5" is only during acceleration deceleration. At idle and 3, 4, 5k water level is less than .25" apart. This is the best TBS I have ever had.

 

Thanks for all the info. (the little I had can be dangerous)

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Ken H.
mecal, the piston (pintle) isn’t supposed to screw in & out on it’s own.. That slot in the threads is supposed to keep the pintle from spinning (it is sort of keyed internally) so as the stepper motor steps the pintle in & out the motor threads can screw the pintle in & out without the pintle spinning with it..

 

I haven’t ever tried on the BMW hexhead stepper motor but on most similar steppers you can sort of wiggle the pintel up & down & around a little & get it to work back into the stepper housing as the threads are not real tight fitting..

 

With the pintle retracted you shouldn’t be able to rotate (screw) the pintle in the housing.. If you can it sounds like maybe a problem internally with the locating key (check it against the other side as a comparison)

 

 

Twisty

I’ve had a hexhead stepper apart (ruined one actually in the name of science) and if the pintle can be rotated; the stepper is definitely either together wrong or defective. One of them I was able to get keyed and back together functioning. Another time I had to discard it. Lesson learned on that issue - don’t turn the bike on with a connected stepper out of the throttle body!

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krussell
[

I’ve had a hexhead stepper apart (ruined one actually in the name of science)

 

Nice!

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CarSalesman

There is an easy way to verify if parking the stepper motors makes any difference to TBS. I don't have an GS911, so will ask one of you to perform the test.

 

Park the steppers with GS911. Perform the sync as accurately as you can.

 

Remove the GS911. Check TBS again - did anything change?

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Don_Eilenberger
There is an easy way to verify if parking the stepper motors makes any difference to TBS. I don't have an GS911, so will ask one of you to perform the test.

 

Park the steppers with GS911. Perform the sync as accurately as you can.

 

Remove the GS911. Check TBS again - did anything change?

I thought we covered this - in depth. The sync only makes a difference above idle - and the steppers are basically out of the circuit once you leave idle speeds (big hole - the throttle plate, vs small hole - the stepper bypass circuit.)

 

So - the answer is - not really.

 

Once you go above idle the steppers fall into sync (same number of counts showing on the GS-911) and you don't do a TB sync at idle.

 

It is nice to know the steppers are "zero'd" out (start position reset) using the GS-911, but I very (VERY) strongly suspect the same thing is done on every startup if you wait for the instrument cluster needle swing to complete. Try putting a finger on one of the steppers and turn the key on.. You'll feel it go bottom and then reopen a bit. Since BMW doesn't use a count-wheel on the steppers (the only way to know if the stepper lost a step/count), it would make sense to reset them at the beginning of every startup.

 

The GS-911 is a great tool, and I do use mine to check if any fault codes have been stored on the bike.. but I don't think it's a necessity for doing a good tuneup on the bikes.

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dirtrider

Hi CarSalesman

 

This TB syncing isn’t as straight forward as it seems at first glance but on the other hand I’m not sure a little side to side discrepancy makes whole lot of difference.

 

There seems to be two schools of thought at the moment on syncing the 1200 hexhead systems.

 

The fist is to just warm the engine then allow the system to idle a short while to allow the steppers to find their place, then just open the throttle and allow the steppers to go to common counts then check the above idle and mid throttle balance.

 

The other is to go by the service manual and park the steppers then see what the idle parked stepper side to side offset is, then keep that same offset in the above idle cable settings.

Per the RepRom manual > ‘’’Check that there is no change in the relationship between the pressure readings when the throttle valves open. The bar that is shorter with the engine idling must also be the shorter when the engine is in part-load operation’’’

 

My personal feeling is to use the first of the setting procedures above as why would I purposely want a side to side vacuum discrepancy while riding at high speed road load , for any reason. Now saying that I “have” played with the side to side balance on purpose just to see if I can make the road load vibration/buzz better or worse. My feeling is who cares about the vacuum being even side to side, I really want the engine POWER to be even side to side regardless of the vacuum reading. Setting the TB balance by vacuum is the easiest and most cost effective so that is what is done but even engine output power side to side is what you are really after.

 

On a long trip a while back I had a lot of open road to cover with no hurry in getting there. I did a very close sync just before leaving on the trip as a base line. I then took off riding in the morning with the sync set perfectly. As I would stop for a leg stretch I would purposely offset one side throttle cable one nut flat, then I went to 2 nut flats offset. I then put that side back and did one then 2 nut flat offsets on the other side cable. I thought I was on to something as the bike appeared to have less vibration with the left side nut turned 2 nut flats so I rode the rest of that day like that. In fact I was thinking I discovered the mother lode on this TB sync thing.

Now comes the next morning, after getting on the road again my high speed engine buzz was back bad as ever. So I set the cables back to where I stated at perfect balance and I seemed to get better. I can’t say with any definite authority that a perfect balance is any better than a slight offset but can say engine operating temperature and outside ambient temperature does make quite a difference in engine vibration.

I think this is one reason so many people ride their bike into their dealer in the cool of morning then have the dealer do the service and TB sync then on the ride home say WOW the dealer sync really makes a difference.

I haven’t followed up on the temperature thing as it hasn’t been a priority so I’m not sure if it is as simple as the air box sensor changing the spark trim between cool and hot, or thicker engine oil forcing the engine to work harder, or the knock sensors pulling spark on a hot engine in hot dry air, or something else. One of these days I will follow up as I have a good base line on my current bike.

 

 

 

 

 

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mike adams

Hi Don,

I moved the throttle stop screws(the ones you should never touch) and need to know what voltage to look for on the wire returning from the TPS. The TPS is not adjustable by moving it as it has no slotted screws.

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Don_Eilenberger
Hi Don,

I moved the throttle stop screws(the ones you should never touch) and need to know what voltage to look for on the wire returning from the TPS. The TPS is not adjustable by moving it as it has no slotted screws.

I have no idea. Did you move them on both sides?

 

Best I can suggest is an absolutely perfect valve adjustment, then use a GS-911 to lock the steppers (and after locking them, unplug them just for good measure) - then use a differential-manometer (AKA TwinMax) to get both the same. When done, reconnect the steppers and do a normal TB balance above idle.

 

As far as the TPS - the ECU on the hexheads is a learning one - it learns the range of the TPS, so there is no reason to have it adjustable. To trigger the learning - disconnect the battery for a minute or two. Reconnect it, turn ignition on (don't start engine) and twist the throttle through the full range of motion. You only have to do this once (despite tales involving multiple times and chicken sacrifices..)

 

Good luck!

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