Throttle Body Sync using GS-911

[mike adams]

I measured the voltage from the TPS at the minimum throttle position. Using the throttle stop screw, I increased the voltage some to make sure it would always come to the same point that is not zero(like the 1100's). I did not know to reset the computer by disconnecting the battery and moving the throttle through a full open cycle. I will try that next. I was able to balance the vacuum at idle by moving only the right hand minimum throttle screw without doing the computer reset. Balancing the cables was pretty easy. I have not ridden the bike yet. I think all I need to do is reset the computer so the TPS will be in a range it is happy with. Thanks for the info- I will report back. Also, have you ever measured the temperature of the exhaust pipes to see if the cylinders are balanced at idle/loaded?

[Don_Eilenberger]

Aside from looking at the color of the pipes - no, I haven't bothered checking the temps. My laser-thermometer doesn't go high enough.

 

I don't worry a lot about balance at idle. I don't ride at idle, and the bike will continuously adjust the idle balance all by itself. The idle quality is really pretty crappy with the current gas sold in the US. I had wonderful idle quality when I was riding in Canada and was able to get non-booze laced gasoline. As soon as I returned to the US - idle went back to imitating a Harley.

 

I don't think getting anal about idle match is worth the effort actually, since watching the steppers using the GS-911 shows the ECU moving them in and out of sync about continuously.

[mike adams]

Here is what I did to my R1200RT. First, the exhaust was so hot on the right side that it turned the pipes really dark, so I took the bike to the local(highly recommended) speed shop for balancing. They did not fix the problem. I tried tuning the stop screws to achieve balance at idle. I removed the right side TB and found that the end of the cable at the TB had separated. The silver piece over the very end of the cable had come off. This was causing the right side to idle on mostly the right side TB. Now I could balance the TB's, but I needed the TPS to be set first. Here is some info you won't need, hopefully. At the TPS, the center wire is vio/yel and changes from .852VDC to 5VDC. I set it at .860VDC by adjusting the throttle stop screw and then did the power off reset. Now balanced the right side to the left using a manometer(stepper motors hooked up). Then balanced at 3K using cable adjustments and manometer. The bike starts up and idles fine. Temperature is the same on both sides idling. I can't ride until my back surgery is healed up in two weeks, so I don't know if I messed up the running at speed. I have had a lot of fun so far.

[Wally E]

I have been reading this thread with interest, and would like to add my bit, and maybe revive this one.

 

I have a GS-911 (Hexcode HQ is 50kms from where I live BTW), and a Motion Pro mercury tube manometer. My bike is a 2011 camhead R1200R.

 

With the engine at normal temp and idling under control of the steppers, there is a slight offset in the height of the two mercury columns. This is with slack in the cables and both throttle plates resting on their stops.

 

This is where my assumption/theory as to what the ECU/steppers are doing at this point comes in. I would think an equal power balance between the cylinders rather than equal mercury column heights is key here. I don't necessarily believe equal heights mean equal power. I think the ECU must be balancing the power by tweaking the steppers (only at idle of course).

 

Let's say it takes x milliseconds for the LH cylinder to drive the crankshaft through 360 degrees. To maintain an equal power balance, it follows that it should take the RH cylinder the same time to drive the crank through the next 360. I would theorise that the ECU is measuring these two time intervals, and balancing them by tweaking the steppers.

 

I get the smoothest running overall if I adjust the RH cable so as to maintain that difference in mercury column heights as the engine rpm rises above idle.

Adjusting so that the vacuum is equal at mid rpm just compromises the "coming off idle" response. Those throttle plates need to come off their stops at exactly the same moment for the best overall smoothness IMHO.

 

Going through the GS-911 procedure, i.e. parking the steppers first, seems to yield pretty much the same result for me.

 

What do the gurus say?

[dirtrider]

Afternoon Mike

 

Tell me you Didn't adjust or move the throttle plate stop screws on a 1200RT???????????

 

If you by chance did then try your best to put them back where they were (maybe match the paint marks back up)

 

Never, EVER move the idle stop screws on the BMW 1200 hexhed/camhead ---- NEVER!!!!

 

Those screws are not even factory set, they are flow set at the TB vendor before shipping.

 

You want to screw up a 1200 just move those sacred idle stop screws.

[Wally E]

Afternoon Mike

 

Tell me you Didn't adjust or move the throttle plate stop screws on a 1200RT???????????

 

If you by chance did then try your best to put them back where they were (maybe match the paint marks back up)

 

Never, EVER move the idle stop screws on the BMW 1200 hexhed/camhead ---- NEVER!!!!

 

Those screws are not even factory set, they are flow set at the TB vendor before shipping.

 

You want to screw up a 1200 just move those sacred idle stop screws.

 

Absolutely agree with you dirtrider. Those throttle plate stops should never be touched! Verboten!

[Andy Graham]

Folks, just found this thread and hoping to get your insight.

 

While on a trip to Big Bend I was riding my friend's new '19 RT while he rode my '09 RT. In an attempt to keep up with me he twisted the throttle to the point that it broke both of the plastic throttle body cable ramps. Ordered the parts from Bing Agency USA and followed their instructions to count the turns on the factory set idle screws in order to properly seat the throttle plate on the new shafts. This is on both throttle bodies so I don't have a prior comparison to go from.

 

I have a GS911 and have observed that the stepper counts at idle once warmed are in the low 60's and not exactly the same. My question is how to get as close to the factory spec as possible without a flow meter? The local dealer mechanic expert had no advice other than buy a new TB which is out of the question.  Attached is a screen shot of the real time readings at warm idle. Appreciate any experience reseting these. Will use a Twinmax or similar to set the sync above idle. Thanks!

 

Funny story.. this happened 3 miles from where Paul Glaves lives down there and he drove over to meet me with an older throttle body he had to try rescuing me. Very small world and kind community. Thanks Paul, if you see this!

 

Andy --

[dirtrider]

5 hours ago, Andy Graham said:

Folks, just found this thread and hoping to get your insight.

 

While on a trip to Big Bend I was riding my friend's new '19 RT while he rode my '09 RT. In an attempt to keep up with me he twisted the throttle to the point that it broke both of the plastic throttle body cable ramps. Ordered the parts from Bing Agency USA and followed their instructions to count the turns on the factory set idle screws in order to properly seat the throttle plate on the new shafts. This is on both throttle bodies so I don't have a prior comparison to go from.

 

I have a GS911 and have observed that the stepper counts at idle once warmed are in the low 60's and not exactly the same. My question is how to get as close to the factory spec as possible without a flow meter? The local dealer mechanic expert had no advice other than buy a new TB which is out of the question.  Attached is a screen shot of the real time readings at warm idle. Appreciate any experience reseting these. Will use a Twinmax or similar to set the sync above idle. Thanks!

 

Funny story.. this happened 3 miles from where Paul Glaves lives down there and he drove over to meet me with an older throttle body he had to try rescuing me. Very small world and kind community. Thanks Paul, if you see this!

 

Andy --

 

 

Morning Andy

 

If you replaced those TB cams or cams/shafts before pre-measuring anything then you are really working in the dark at re-assembly.

 

Counting idle screw turns is pretty meaningless unless the throttle plates & throttle shafts are perfectly centered back to where they were before disassembly.

 

If you didn't mark (scribe) the throttle plates to the sides of the throttle shafts  before disassembly then getting the plates back in & clocked correctly is very difficult.  

 

Also, you need to get the engine running long enough & hot enough  for the  fueling control to go into closed loop (active lambda sensors) before the stepper counts become independent.

 

Maybe read the how-to (link below)  that I posted a while back on throttle shaft/cam replacement as maybe there is something in there that can help you get your throttle shafts centered & the throttle plates clocked correctly. Note: when I wrote that preliminary procedure I had only done that one set of TB's  using that procedure  but have since done a few more shafts/cams installations  & the procedure has worked good on all TB's so far.

 

At the very least you might be able to use feeler stock to at least check that both side throttle plates close to the same plate-to-throttle-bore clearance when resting on the idle stop screws.

 

https://www.bmwsporttouring.com/topic/92006-posted-to-see-how-a-tb-shaft-install-how-to-reads-in-a-full-thread/?tab=comments

 

  

[Andy Graham]

Thanks for your quick reply dirtrider... I got to this point because the Bing Agency folks instructed to back off the set screws to allow the throttle plate to sit flush in the bore before tightening the shaft clamp screws - then return to their original positions.

 

What you're saying is that I can't use the GS911 and stepper counts to adjust these gaps? The gaps have to be both uniform and positioned to allow a defined amount of air flow presumably set by a machine at the factory. As you point out - I now do not know what the original gaps were. Is there a specified measure based on the ones you have worked on?

 

The Bing Agency said over the phone that BMW does not share with them how they make this setting.

 

Finally, what is the worst case? The engine does not idle properly? Sync at 3K and above based on vacuum should be OK there?

 

Thanks again,

 

Andy --

 

[dirtrider]

Morning Andy 

 

 

I got to this point because the Bing Agency folks instructed to back off the set screws to allow the throttle plate to sit flush in the bore before tightening the shaft clamp screws - then return to their original positions.-- This seems to be the way that they do it, just remember that 'they' are Bing USA & not the original Bing in Europe  (basically they just sell parts). When I did my first set I did call Bing USA about their procedure but was not convinced that backing the idle screws off then back to where they were was very accurate (that is when I tried to develop a more precise procedure).  

 

What you're saying is that I can't use the GS911 and stepper counts to adjust these gaps?-- You might be able to BUT only if you had taken the stepper counts before your throttle cam failure & could duplicate the very same engine loads & same engine temperature that the original stepper data was taken at.   

 

The gaps have to be both uniform and positioned to allow a defined amount of air flow presumably set by a machine at the factory. As you point out - I now do not know what the original gaps were. Is there a specified measure based on the ones you have worked on?-- Yes & no, the ones that  I have done did have a measured & defined air flow gap BUT that was determined using feeler stock before any disassembly. (read back through that link that I posted as the pre-disassembly gaps are in there. This also assumes that the throttle plate clocking is EXACTLY the same at re-assembly as at it was at  pre-disassembly. (those throttle plates are elliptical)

 

The Bing Agency said over the phone that BMW does not share with them how they make this setting. -- That is why I didn't  even try their idle screw procedure as it isn't tested or verified with any type of test/verification data. 

 

Finally, what is the worst case? The engine does not idle properly? Sync at 3K and above based on vacuum should be OK there?-- The good news is that probably effects cold engine starting more than anything, it shouldn't have a lot of effect on the 3K sync (as long as the GS-911 locked stepper base idle cross side vacuum is not too far off).

 

At hot engine idle the steppers should be able to even out the idle as long as the stepper counts are somewhat centered in their lower operating range. 

 

Cold start -- Just after cold-start  idle could be effected if the BMS-K (programed)  stepper counts are not high enough to keep it running properly due to improper throttle plate air flow gaps. Once it idles for a second or two the BMS-K should catch up & be able to dynamically adjust the stepper count to keep it running.

 

You might be able to check your basic cross side idle balance by using the GS-911 to lock the steppers on a hot idling engine, then use your manometer to see how close the idle vacuum is side to side  (if it is fairly even side to side  then you probably got it close using the idle screw back-out count __  then back in to the same place). 

 

If it is off more than 25 mbar side to side then you have a basic base idle screw issue  & should try to even it out. This should get it  somewhat even at idle but won't put your hot engine idle stepper counts back to their original  position (but, if it cold starts OK, stays running OK after a 'no added throttle' cold start,   & doesn't stall at  a quick dropped throttle stop then you can probably live with where it is at now.  

 

 

 

 

 

 

[Andy Graham]

Thanks for the very detailed response. I visited the local dealer to see if they had in any info on default flow settings for the throttle plates at hot engine idle and like you said it should not vary more than 25 mbar. They also said that the stepper count should be 20 or below if both sides are set correctly at full operating temp. What I noticed on their computer image associated with the spec is that the absolute vacuum was -245 mbar. Of course, I'm sure this depends on a number of other operating factors.

 

I was careful to be sure the plates sat square in the bore with no side or spring load on the shaft, but if all I have in the end is cold start weirdness then I'll declare victory.

 

Thanks again!