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RT stumbling, TPS suspect


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Hi all,


My own 07 R1200RT has a bit of an annoying problem, in that at low rpm it stumbles, especially with the throttle just off the stops. While moving, throttle about 1/4 open, it feels like it's hunting, not keeping steady power.


I've read a few threads about this and read about the usual suspects.


I connected the GS911 and looked at the TPS values (and O2 sensor voltages).

I noticed that, while running, the TPS value didn't remain constant with steady throttle.

I tried it with the engine off and saw perfect tracking of every movement.

Restarted the engine,slipped on the yellow O-ring throttle lock and revved to 1500-1800-2500- 3000. Once again I noticed the TPS values dropping, simultaneous with drops in RPM.

For instance, the GS911 reported .78 with dips to .39.


Now, is this a smoking gun for a failed TPS or cable connection?

or is the reported drop a function of dropping voltage when the enginge stumbles or similiar?


I'll try to get hold of a set of stick coils for testing, as that would appear to be next in line anyway.


Thanks for the help,



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Morning Daniel


That dropping off is not characteristic of a failing TPS, that type of TPS voltage drop is usually more in line with a throttle cable seating issue or some type of throttle control issue.


With the TPS voltage tracking true with the engine off (key on) that kind of contradicts the above as you would think a throttle cable or cable routing issue would also be there with engine off.


Make sure your throttle cables are fully seated in the splitter box as well a routed correctly.


Anything done to the bike just prior to this problem happening? Any service or any accessories added?


If nothing else found then monitor the 5-volts going to the TPS as well as the low (ground) coming from the TPS as either the 5v reference or the low could be causing your voltage fluctuation.


Also-- are the TPS screws tight???


Added: can you trap a .csv log when the problem is happening then post it here? Maybe we can spot a problem in the trapped data.




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Nothing done recently, but I haven't been riding it much, as it's the wife's. So it might have been there for some time.

Last time the cables were touched was some 10 months ago, service at the dealer when we bought it.


I'll check the TPS-screws and get a log this weekend.





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Got the CSV log.


First one is from cold start. Dropping TPS in evidence.




After a while i noticed that the bike didn't register tiny throttle openings, if you gave it just a little throttle rpm would rise, albeit poorly, but the 911 would show 0% opening.

So I made anpother log, this time focusing on minor throttle openings.





I considered that it could be an imbalance in the throttle cables, with the right one of it's stop before slack is taken up at the left one, or that the adaptation was wrong.

So I cleared the adapted values. GS911 showed 10% opening with throttle closed. Twisted the throttle 3 times and it showed correct values.

Made another log, still focusing on small openings.




interestingly, the initial takeup was better, the bike registered them correctly. Falloff still present, somewhat.


Haven't had time yet to strip her down to fully investigate cables, TPS screws or the coils.





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Morning Daniel


It is difficult to tell from the data where your throttle Twist grip) WAS when the GS-911 shows a certain throttle opening. It sure doesn't seem to track smoothly but without knowing the twist grip position vs throttle angle it is difficult to tell much.


I do see the RPM come up but that could be from the non TPS side throttle opening earlier than the TPS side.


So, yes, do check the cable operation, especially pay attention to the cross side lifting of EACH side throttle cam off the idle stop.


If you have a balance gauge (like U tube manometer) hook that up to see if the side to side vacuum is tracking somewhat evenly as you open the twist grip.


If the vacuum is close at throttle opening then suspect your TPS as being an issue (or 5v reference or low problem to the TPS)


You battery voltage also looks a little low at cold start up so possibly your TPS is losing it's learn at cold startup so maybe try running engine until warm, then do a battery disconnect TPS re-learn, then do a re-start & ride the bike for the hesitation problem. If it is gone then maybe the TPS is losing it's learn at cold start. If problem is still there then look for a throttle opening discrepancy (cable issue) or a bad TPS (or TPS voltage/TPS low issue)


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