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Bad TPS @ 17K miles? R1150RS

I recall farting around with my TPS a lot during the purge the surge era a few years back. One thing that your post reminded me of is when you crank the TPS all the way to one side or the other there is no limiting going on. It just runs right off the traces and suddenly there is a wild change in resistance measurements all the way to no resistance at all. This surprised me at the time but when I looked at the mechanical drawings from Bosch it made sense. They have an operable range and beyond that, nada! It falls off a cliff as they say...

Good to hear you've nailed this down. It is a very rare failure but so is breakage of the needle click spring retainer clip on a Bing CV carb but it just happened to me last Sunday. I scratched my head for a while on THAT one...
 
Mama never said it'd be easy...

Well HW... sometimes it helps not to suffer alone, eh? I get so wrapped up in idiosyncrasies that I often times think that all the weird stuff happens to me and me alone.

Once the new to me unit arrives and (hopefully) solves the issue, I intend to do as pauls1150 and take the old unit apart to see if there's visible indication of the failure (doubtful.) I toyed with the idea of drilling a small (~1mm) hole in the top of the unit, a ~ 2 mm drain hole in the bottom, shoot it full of component cleaner and see what happens once it dried out. Perhaps once I have a little more time...

Thanks for your time and support!

-l-
 
Damn!

Well, received the "new to me" part from Re:cycle... same issues. Re:cycle stated the part was good and from a running bike. If so, then I'm more stumped than before, but this is operating on an act of faith.

I again tried to set the TPS with the gs911... same "idle switch" error. I completely disconnected the cable running from the cold start lever... no change. I then started the scooter. Initially, the gs911 showed a cycling of off and on of the idle switch which then changed to on and stayed on. Peculiar?!

As I was running out of ideas, I cycled through the gs911 tests and tried the fuel tank vent valve test. I heard a servo cycling but the status of the test never changed from "off." I cannot find anything that states if this is normal, but it intuitively doesn't seem like it would be. This would also explain why the bike is wonky when warm. This is completely off the initial topic and explains nothing with regards to the TPS issues, but is interesting, no?

So, still at the same place, i.e.

Gs911 calls foul on the TPS.
Fault seems to be un-clearable.
Trying to make adjustments via gs911 ends in tears.

Brain teasers aren't always the fun they seem to appear...

-l-
 
Check the throttle stop screw, has the paint been disturbed?

Did you point to point test each wire from the TPS plug back to the actual pins on the motronic plug?
 
The way I have been testing TPS sensors that exist on just about anything that requires an angle sense is by voltage.

Start with finding position #2, which is voltage in, around 4.5V to 5.0V, and check to ground.

Find Position #4, which is sensor ground, check to make sure you have 0 as in zero resistance to ground. Even a 0.5 ohms is too much resistance.

Go to #1, negative side of your meter on #4, that is idle and must be below 2.0V. If it isn't and you have it turned all the way in either direction, you may be dealing with someone tampering with the initial butterfly position opening such as the painted screws.

Now, try #3, negative on #4, voltage should be the same as when you are on #1. Turn throttle, voltage should climb in a linear fashion.

You can do all of these tests with the TPS connected and back-probing using the very expensive BMW paperclips.

This is all making assumptions that you have checked the fuses, as in pulled them out, inspected them and you have made sure all of your grounds are clean and free of corrosion.

This is a no-brainer problem. The problem is getting the brains in my head to explain it without that nagging inner voice telling me to go for a ride.
 
Back from the verge...

Sorry for being absent from this post... troubles on the home front needed my undivided attention. Not having checked this site in a while, I went back to tinkering yesterday afternoon as a means to alleviate stress @ home... just went about the business of putting things back together... along with a new-to-me fuel tank vent that I picked up for $15 w/shipping from ebay. I took the scooter off the lift and decided to see how wonky things lay at this point by taking a 30 mile ride to the nearest gas station. The bike ran absolutely perfect! It was ~ 85F... 15 miles to the station got things good and warm. I was sure that there would be the hesitation issue after fueling... NONE! Amazing!

So... at this point:

Bike runs better than since I picked it up last year... seems almost like a new machine!
new-to-me TPS and fuel tank vent in place (this may have solved the hesitation/fuel starved symptoms... will further evaluate)
gs911 still reports errors
old fuel tank valve seems to be full of what I assume to be chunks of carbon that fall out as I tap the old unit on the bench


In answer to your question... I did trace wires... 'seem to be continuous back to the computer. I've not yet checked voltages from the TPS (as I just saw the post and methodology (THANK YOU!))
.
I am temped to run the machine until I start experiencing more performance issues, then dig into it again. With home life on its ear at this point, I may not be checking in as frequently, buy will be back... 'seems to aid in the healing process!

Thank you all for your help!

-l-
 
"Chunks of carbon" is exactly why some of us have, um, accidentally lost the whole black canister setup and its associated hoses (and capped off the ports on the bottom of the throttle bodies).

Just a thought, casting about for ideas on a "root cause": This makes me wonder if maybe a chunk got trapped inside a throttle body; most likely places would be in the tube where the hose hooks up to the t-body, or in the idle air passage (and we hope it didn't weld itself to the intake valve), but someplace else might inhibit that body's proper operation? And just a long shot (real long...), but if it was stuck in the left body, might that prevent the throttle from returning to fully closed (except for a couple of degrees to permit a proper idle), in turn inhibiting the operation of the TPS and/or cold-start lever...
 
Apologies for my abscence

Greetings and thank you all for your input on this issue. Due to a divorce, I fell off the face of the earth for a few months. Back now and working on recovery.

I have the RS on the lift and am preparing to tear into it again in the next few weeks. I'm beginning to think that the issue is the O2 sensor. Some "therapy rides" I took recently sure seem to point to that... i.e. stuttering/fuel starvation after a few minutes of sitting shut off after a long ride.

I apologize again for my disappearance... couldn't be helped. I greatly appreciate everyone's time on this. Bear with me... I'll update this as soon as I have any news.

Thanks much,

-l-
 
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