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Syncing Throttle Bodies- Stelvio 8V

john zibell

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Scott, You also need to do the TPS reset after you complete the balance. In my opinion, the first TPS reset really isn't necessary. However the after Throttle Body Balance a TPS reset is critical as the TPS sensor is moved during the balancing procedure.
 

scottmastrocinque

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Scott, You also need to do the TPS reset after you complete the balance. In my opinion, the first TPS reset really isn't necessary. However the after Throttle Body Balance a TPS reset is critical as the TPS sensor is moved during the balancing procedure.

Hi John,

That’s in number 5. Maybe you didn’t see it?

Opening an air bleed doesn’t move the TPS sensor or the adjusting plate so a TPS reset would be superfluous in number 6. Right?

I think I got this right... Yes? No?

Thanks again. Nice to see you well and around - or perhaps I should say, it's nice to be back around. Strange, I've missed this place. LOL

Best Regards!
 
Last edited:

john zibell

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I see that now. Sorry, I'm accustomed to writing procedures for soldiers. We never wrote long procedures in a single step but broke out each process. Never bury a critical step in a long paragraph. Break it out into a stand alone step. That last TPS reset is the critical step.
 

AZRider

Just got it firing!
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Jul 27, 2013
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REPOSTED 4/4/19 WITH LOCAL FILE POSTING: PHOTOBUCKET NO LONGER WORKS!

No Problem. I think it becomes clear when one fully understands what is happening here, so to this end, let me offer this.

<A Truly Fantastic Set Of Illustrated Instructions>

I sincerely hope that this explanation helps you. Good Luck! :D

YES, yes it did help. And I've been to Guzzi factory technician school.
 

Chris E

Just got it firing!
Joined
Nov 20, 2020
Messages
4
Location
Anderson, CA
Greetings. I am a newbie on the forum and have been looking through many threads, finally arriving on this one. Just what I needed! I am the owner of a 2013 Stelvio since April 2020. I have done some minor maintenance, and I now have a Carbmate and Todd's ECU flash tool on the way. Not being much of a wrench (but willing to give it a go) this thread, along with Scott Mastrocinque's outstanding explanation and photographs, have me feeling confident my Stelvio will be running top notch soon with a throttle body sync and ECU update.
 

KayJay

Cruisin' Guzzisti
GT Contributor
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May 26, 2016
Messages
116
Location
Florida
REPOSTED 4/4/19 WITH LOCAL FILE POSTING: PHOTOBUCKET NO LONGER WORKS!

No Problem. I think it becomes clear when one fully understands what is happening here, so to this end, let me offer this.

This is my lousy drawing of the throttle-bodies arrangement on the Stelvio.


View attachment 16827


As you can see, there are butterfly valves inside of the throttle-bodies. As they open, more air is drawn in from the airbox to mix with the injected fuel. The blue line connecting them together, is the linkage rod so that when one turns, the other turns the same amount. The yellow arrow is the location of the fast speed throttle-body balance adjustment screw. The red arrow is the stop plate screw which is factory set and you should NEVER touch otherwise the whole thing is ruined and must be replaced! The green diamond is the TPS sensor which resides on top of the right hand side throttle body. Now let's look at real pics.

Here is a side view , pointing towards the rear of the left hand (sitting on the bike) throttle-body. The colored arrows match the previous diagram. Yellow is the adjustment screw, red is the stop plate screw you never touch.

View attachment 16829

Here is the same side taken from a more straight on angle. Again, yellow arrow is adjustment screw, red arrow is factory set stop plate screw you do not touch, and now the white arrow shows the connecting rod which goes over to the right hand side throttle-body (in my lousy graphic, this was the blue line connecting the two throttle-bodies together).

View attachment 16830

Here is the best view. Notice the white circle which shows the connecting rod going all the way over to the right hand throttle body, and the red circle which shows the factory set stop plate screw resting against the stop post from the throttle-body. This is why you never adjust the stop plate screw (red arrow) because this distance is a factory calibration which is linked to the fuel injection software as to it's position, approximately 4.9 degrees. Basically this distance is a constant so that the fuel injection map, which depends upon throttle POSITION (i.e. open or closed within it's range of motion) is calibrated at a ZERO point. It will make more sense in a moment.

View attachment 16831

This is the throttle-body on the right-hand side. The green diamond is the TPS sensor. The white circle shows the connecting rod coming from the left-hand side which connects to the right-hand side. The throttle cable only attaches to the left-hand side throttle-body. All movement on the right-hand side is controlled by this linkage rod. You never adjust or change this rod. It too, is factory set.

View attachment 16832

View attachment 16833

Now, let's look at the bleed screws. Left-hand side first. It is the blue arrow and you can make out the hex head on the inside of the screw. You can also see an excellent view of the factory set stop plate screw in the red circle.

Also look carefully at the yellow arrow (the fast speed throttle body balancing screw). See the mechanism with the spring? When you turn this screw, it allows the secondary plate (on the right side of the spring)to move INDEPENDENT from the left side of the spring. So, the plate on the left side of the spring is the left-hand throttle-body. It NEVER moves from the factory set position. The plate on the right side of the spring, is connected to the control rod which goes over to the right-hand side throttle body. Thus, when you adjust this screw, you are physically moving the butterfly valve in the right hand throttle-body! Get it? )You can see the two independent plates in the second photo) The left side never moves adjustment wise, but the right side can be adjusted in or out as needed to balance the high speed balance. Remember, the TPS sensor sits on top of the right-hand throttle-body - i.e. the one that can be MOVED. The fuel injection computer orders the injectors to do their thing based upon certain conditions which it always is evaluating, one being throttle position, and if we moved the butterfly valve on the right-hand throttle-body, the TPS will read an incorrect position (voltage) from the TPS sensor from the get go and our fuel injection map will be out of alignment with actual operating conditions.

Now this is WHY you need to be able to reset the TPS. Remember that the TPS position is linked to the fuel injection map in the ECU. In order for the throttle position and the fuel injection map to be in alignment there has to be a synchronized ZERO point. That point is the value set by the factory on the left-hand set plate screw of usually 4.9 degrees and this is why you NEVER adjust this screw. But we do reset the TPS so that the altered-position of the right-hand throttle-body, is set to match the factory baseline setting of 4.9, (this is what the left-hand side will ALWAYS BE - IT CANNOT EVER MOVE SO LONG AS YOU DON'T TOUCH THE STOP PLATE SCREW) regardless of where it actually is, so that everything is in alignment. Left-hand side physically and permanently always at 4.9 and right-hand side electronically reset to 4.9, irregardless of where it actually might be in order to properly balance the throttle-bodies. Does it now make perfect sense? Now you understand precisely WHAT is happening and when.

So, when we adjust the fast speed adjustment screw, we are moving the right-hand throttle body out of alignment from the permanent factory setting on the left-hand side, in essence, because the TPS sits on top of the right-hand side, we have moved the alignment of the throttle position with the fuel injection map. Bad thing - crappy running motorcycle.

So, when we RESET the TPS, we are telling the ECU that the value it is reading from the TPS sensor on the right-hand throttle body, should be the ZERO point (in actuality, the 4.9 factory setting which is what the left-hand side is), REGARDLESS of where the right-hand side has been moved to, thus aligning the throttle position and fuel injection map, while maintaining the actual true zero point which is physically set by the stop plate screw on the left-hand throttle-body at the factory.

We are commanding the ECU to recognize and program that at whatever position the right-hand throttle-body is at right at that moment (remember, we may have moved it left or right by adjusting the fast speed throttle-body balance screw), should be reset to the baseline 4.9 (in this particular model, others are different). We are setting that ZERO point to align the TPS sensor and the FI map to the actual operating conditions (the real position of the right-hand throttle-body).

Had the factory put the TPS sensor on the left-hand throttle body, we would never need to reset the TPS and could move the fast speed adjustment screw anytime we needed to without worrying about a TPS reset. However, because they put the sensor on the RIGHT-HAND throttle-body, and because this position can be changed via the fast speed adjustment screw, we must be able to tell the computer to reset the zero position (which it reads on the right-hand throttle body via the TPS sensor) after we've made changes to the fast speed balance adjustment screw. I hope this makes complete sense now. :geek:

View attachment 16835

View attachment 16831

Let's look at the right-hand side air bleed screw. Again, you can see the hex head inside of the bleed screw. These screws are a BEAR to get to, especially the left-hand side.


View attachment 16833

View attachment 16836

View attachment 16834


So, the general idea is this.

1. Connect your Centurion to the bike and turn the ignition switch on. Reset the TPS with the Centurion. (We are establishing a ZERO point based upon the position of the right-hand butterfly valve position).

2. Close BOTH air bleed screws. More than likely, only 1 will be open. Remember, closed, but not crushed! A light touch works really well here.

3. Place a large high-velocity fan right in front of the motorcycle, blowing towards the motorcycle to keep air flowing over it during this procedure. This is a MUST DO to avoid overheating! Bring engine to operating temperature > 60 degree Celsius (The Centurion you can buy from Todd here on the forum, will display the engine temperature from the engine temp sensor, very handy).

4. Turn off engine, attach your CarbMate, mercury stick, or whatever tool you are using to balance the throttle-bodies, to your vacuum ports on the bottom of the throttle-bodies, one on each side.

5. Turn engine on, and have an assistant raise speed to approximately 3800-4000 rpm and hold it there steady. Look at your balancer, and adjust the fast speed throttle-body balancing screw to bring the throttle-bodies into alignment. Turning the screw one way will raise the right-hand vacuum and turning it the other way will lower the right-hand vacuum. You will understand when you do it. CAUTION! It is easy to push on the screw while you are turning it, and this will raise the rpm erratically (you are pressing in the linkage and moving the connecting rod). The trick here is to ROTATE the adjustment screw WITHOUT pushing against it. It takes some getting used to. When you are doing it, you will instantly notice if you are pushing against the screw because your engine speed will change. Personally, I use a socket attached to a screwdriver-type handle to rotate the screw but you will have to scrape away some of the yellow marking paint for your socket to slide on easily. The socket allows for better rotation without pushing into the screw. When the fast speed adjustment is balanced, release the throttle back to idle. Turn off the engine and reset the TPS again. (We are resetting the zero point now that we have changed the position of the right-hand throttle-body via the fast speed balancing screw). When done. Disconnect your Centurion from the motorcycle.

6. Start engine again and blip the throttle and then release it and allow it to click back against the stop screw. Now at idle, what does your balancing tool say? More than likely it will read different values. The side that is HIGHER, is the side you want to open the air bleed screw on, thus allowing more air to enter and thereby reduce it's vacuum. (Don't touch the other side air bleed screw. It's not necessary.) Only one side is the higher side and if we open that side's air bleed screw, it's vacuum will become less, and as you adjust (open) the screw, the balancer tool you are using will show the throttle-bodies come into idling alignment. Once the alignment is the same for both throttle-bodies, by having adjusted ONLY the higher side, you are done!

7. Turn off engine, disconnect balancer tool, cap off your vacuum ports, and smile. You did it.

I sincerely hope that this explanation helps you. Good Luck! :D
Great write up! I know this took a lot of time and it is by far the best explanation I have seen (and I have seen several). I am extremely grateful! Now I understand completely!!
 

scottmastrocinque

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Great write up! I know this took a lot of time and it is by far the best explanation I have seen (and I have seen several). I am extremely grateful! Now I understand completely!!

Thank you! You are most welcome. If you have any further questions, feel free to Private Message me.
 

Meon2wheels

Loving Life
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Sep 17, 2021
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Cincinnati, OH USA
I did this procedure today as part of 6200 mile maintenance on a 2014 Stelvio I bought last year. Instructions were very helpful. ECU box was easy to use. I used a pneumatic vacuum bank. Had to adjust the high speed balance slightly as well as the idle balance. Bike runs awesome. Thanks for a great writeup Scott that save me time and heartache I'm sure.. Jim
 

scottmastrocinque

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I did this procedure today as part of 6200 mile maintenance on a 2014 Stelvio I bought last year. Instructions were very helpful. ECU box was easy to use. I used a pneumatic vacuum bank. Had to adjust the high speed balance slightly as well as the idle balance. Bike runs awesome. Thanks for a great writeup Scott that save me time and heartache I'm sure.. Jim


You are very welcome! I am pleased you utilized it. Best wishes!
 

maverick9611

Tuned and Synch'ed
Joined
May 8, 2022
Messages
60
Location
augusta,georgia
i recently did this on a 2015 norge. the pics and explanations are very detailed.
i never did see tool requirements or size of vacuum adapter. i had to order a pair thinking the throttle body had this mounted already. (i'm a newbie)
tools needed:
motion pro vacuum adapter 2EA size 6mm x P 1.0mm)
amazon/ebay has them, order 2 as the pic shows 4 (actually its only 1 you would be ordering)
8mm open wrench for removing vacuum bango fiitting(don't lose the small seal o ring)
7 mm socket on a screwdriver bit extension for the fast idle screw(remove yellow paint to adjust)
pliers/needlenose to tighten vaccum adapters onto throttle bodies
5 mm allen wrench for air bleeds. you will need visegrips holding end of allen wrench to adjust air bleeds once engine is hot. i tried, you will not be able to get close to that heat.
inspection mirror to help locate air bleeds( left is difficult)
flashlight to help locate air bleed and to help you line up allen wrench to open/close it.
blanket. best way to adjust air bleeds is to lay down and look up at it, will trying to get allen wrench to engage it. you will holding flashlight at this time to see air bleed. your neck will hate this position.
i hope this helps.
 

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Nicolai

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Location
World 02138 and France
Greetings all. Only adding abundant GRAZIE for this detailed procedure which I've now done on my three successive Stelvios (2012, '13, & '17). On two of them ('12 & '13) the ECUs burnt out (also on my Dodge Dakota and BMW F650GS - must be a jinx...)! My 2012 is in France and a friend (more gifted than I for web searching) found me a new one which I'm hoping to mount in time to get to the Centenario Raduno.
As regards tuning, I found that the final micro tweak of the bodies sync went better 'by ear and feel' of throttle; I have the Carbmate and another set of gauges, but that 1/64th of a turn I got best without any gauges (IMHO).
On another note, having bought my '17 new (from terrific Jim Hamlin in CT) in '19 (to replace the beat up '13 in 2021), I noticed that the clamps holding the original vacuum lines originally mounted on the bike were ever so slightly loose, which caused a bit of rough idling and backfiring. I replaced them with stainless hose clamps which appears to have solved this.
Maybe we'll meet in Mandello this September?
Safe rides to all 🙏
 

scottmastrocinque

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It’s always very gratifying to read that this has helped people. Thank you.

It took a lot of time to create but it was worth it I think.

👍👌🙏
 
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