Help! Bike accelerating by itself, won't respond to closed throttle

[Nimbus]

Hey everyone,

I posted up a long while back that my bike seems to have a weather related issue that I came to suspect was the throttle position sensor. It still has a weather related issue, but now I'm less sure what it is. Today (33 degrees and very humid) I rode to work and after the bike warmed up, the revs dropped to <1000rpms and it died. Fun hard start in traffic and then it decided it would just rev itself to 3500. Restart didn't help. I seriously was going 40mph without the throttle. Now, in the past, I assumed it was the TPS because when the revs would briefly hold before settling to a bit higher idle than normal, the mode switch wouldn't work. The last times this happened it was on cold and very foggy days. I assumed that the ECU was reading that the throttle was "open" and so would not allow the map to change. But today, going 40mph with my hand off the completely shut throttle, the mode switch toggled between S and T as normal. I cannot for the life of me figure out WTF is happening with this bike.

And, a bit of extra info, the last time the bike did this, it had less of the high rev hold symptom and more of a very low idle problem. On that occasion, it would briefly hold revs between shifts (never, like today, with hand off the throttle) and then settle to a lower than usual idle.

Any thoughts?

 

[squarebore]

Sorry I can't help mate, sounds like a problem for the dealer to me. Do you have any warranty?

 

[Checkswrecks]

Usually, I am fast to offer above or troubleshooting thoughts. My first thought here is that it could be a crack in the case of the ECU, TPS, or some other component.
But my second thought is that this is a problem that you REALLY don't want to misdiagnose. I have a big scar on my foot from a throttle that hung up at the wrong time.
I'd suggest letting a shop look at this one.

 

[shrekonwheels]

Interesting, have had mine stay at a high idle before while cold, even after warming up for a couple minutes making the first couple of stops annoying. I will have mine looked at first thaw, stay safe and go to the dealer.

 

[stutrump]

Cant help sorry. If and when you do sort it please let us all know what it was. Good luck!

 

[HHH]

I would have the battery checked.

 

[Lutsie]

Have any aftermarket map accessories ie. autotune, power commander, alarm system any aftermarket electronic tied into the ecu?

 

[fredz43]

My 2012 did that once, intermittent idle about 3,000-3500 RPM. I found a vacuum leak in the rubber cap that goes over the right throttle body port. A new rubber cap and all was well.

 

[Nimbus]

My 2012 did that once, intermittent idle about 3,000-3500 RPM. I found a vacuum leak in the rubber cap that goes over the right throttle body port. A new rubber cap and all was well.

Funny. I replaced a vacuum cap two days ago that was completely disintegrated (to the point you could see the brass nipple through the frayed rubber). I replaced it because the bike stumbled/stalled at low idle at 25 degrees. Once it (finally) restarted, it stumbled a bit at idle, but not predictably and without holding revs. I assumed that I had fixed the old problem. I put on a new cap, but maybe it went on too easily. How would the vacuum leak influence that big of a throttle issue?

 

[whisperquiet]

Read this thread... http://www.yamahasupertenere.com/index.php?topic=12376.msg217151#msg217151 I don't know if the OP's problem is related...but, who knows. I cycled the TPS numerous times when I performed the valve clearance check and it totally cleaned up the fly by wire throttle response on my bike. Just a suggestion.

 

[broberts]

My early 12 with about 25000 miles did this same thing one time. It was dry , in the 60's after a 300 mile run . Pulled into the motel cycled key couple times and it's never done it again in over a year.