Rocket III stumble at slight throttle

Deets55 said:
Bob,

Does your bike have a TPS? Sometimes they develop a worn spot (usually in the area right off of idle) that will test out well, but stil cause a problem. Sometimes they can be re-adjusted to a different value to check for a change in performace/test. Other times you have to bite the bullet and just get a new one if you suspect that it is the issue.
Pete
Click to expand...
It does, and I tried adjusting it, the displayed values were not linear, as expected.
This is a good idea.
 
Deets55 said:
Bob,

Does your bike have a TPS? Sometimes they develop a worn spot (usually in the area right off of idle) that will test out well, but stil cause a problem. Sometimes they can be re-adjusted to a different value to check for a change in performace/test. Other times you have to bite the bullet and just get a new one if you suspect that it is the issue.
Pete
Click to expand...
Adding to what Bob said most aftermarket ecu 's , well on my MoTec car computer the tps Is zeroed for Hi/ Low position obviously key on no throttle an then full throttle for the high position, I think stock ecu just have a voltage setting i:e .98v low and 5v high , something like that , also when in that setting screen you could watch the numbers or percentage going up , if there is a dead spot you may see it . Is your oxygen sensor just there for a 5 % either side of the base tune . Make sure your ecu is hooked up direct to battery, good connections , get the coms sorted or get a dyno tune guy to put his oxygen sensor in its pipe and check and adjust as required ,some of those guys are really good .
 
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Deets55 said:
Bob,

Does your bike have a TPS? Sometimes they develop a worn spot (usually in the area right off of idle) that will test out well, but stil cause a problem. Sometimes they can be re-adjusted to a different value to check for a change in performace/test. Other times you have to bite the bullet and just get a new one if you suspect that it is the issue.
Pete
Click to expand...
....aaaaannnnd @Deets55 WINNER WINNER, CHICKEN DINNER!
Thank you for sharing that, the more I thought about it, the more it made sense.
Stumble is GONE!
Beers are on me next time!
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....and THANK YOU to Tornado, Shelby, Flatspot who contributed.
Great talent brought to bear. 🍻😎

Nigel... I'll be in the poor house or in jail.... 🚀🚀🤡🤠
www.rotrex.com

Triumph Rocket 3 Supercharger Kits

Triumph Rocket 3 Supercharger Kits - Each Triumph supercharger system is a comprehensive design and includes all necessary components.
www.rotrex.com www.rotrex.com
 
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I'm not sure who sleeps less, me or you.
Looks great!
Getting ready to head out to "The Gathering of the Norton's" as soon as the rain stops.
 
Deets55 said:
I'm not sure who sleeps less, me or you.
Looks great!
Getting ready to head out to "The Gathering of the Norton's" as soon as the rain stops.
Click to expand...
I'd love to go. Next activity is riding to Tennessee three weeks from now...🪕🍻
 
Late to the party with this vid, but you can see the secondary throttle plates fluttering. At about :35 to :40 you can see the tach really surge. All with a steady held throttle.



Thanks again for planting a seed Deets.

We now know:
The flakey TPS > bogus erratic signal to ECU > commanding the stepper motor for the secondary throttle plates to move in an erratic fluttering motion, also commanding the injector pulse width to vary erratically.
All with no CEL, no stored codes.
 
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concours said:
....and THANK YOU to Tornado, Shelby, Flatspot who contributed.
Great talent brought to bear. 🍻😎

Nigel... I'll be in the poor house or in jail.... 🚀🚀🤡🤠
www.rotrex.com

Triumph Rocket 3 Supercharger Kits

Triumph Rocket 3 Supercharger Kits - Each Triumph supercharger system is a comprehensive design and includes all necessary components.
www.rotrex.com www.rotrex.com
Click to expand...
Glad you solved it. Now you have me wondering about my TPS. The manual says to check voltage output at idle to be 0.6v. Mine has that so figured it to be a good'un. If it has a "flatspot" or unstable output at other throttle positions, could explain my continual power dips.
New unit is a cool $200 Cdn so not something I just want to throw on without assurances.
 
concours said:
Late to the party with this vid, but you can see the secondary throttle plates fluttering. At about :35 to :40 you can see the tach really surge. All with a steady held throttle.



Thanks again for planting a seed Deets.

We now know:
The flakey TPS > bogus erratic signal to ECU > commanding the stepper motor for the secondary throttle plates to move in an erratic fluttering motion, also commanding the injector pulse width to vary erratically.
All with no CEL, no stored codes.
Click to expand...

Certainly more extreme than my Bonneville. There is not secondary plates on the twin, no auto choke or fast idle. There is only a cold start manually operated "choke" knob, which lets more air past throttle plates.
But the TPS must be feeding the ECU to control something, either spark advance or injector pulse width I suspect. So if it is giving spurious signals, expect unstable engine rpm.
 
Tornado said:
Glad you solved it. Now you have me wondering about my TPS. The manual says to check voltage output at idle to be 0.6v. Mine has that so figured it to be a good'un. If it has a "flatspot" or unstable output at other throttle positions, could explain my continual power dips.
New unit is a cool $200 Cdn so not something I just want to throw on without assurances.
Click to expand...
I intend on a post mortem, of the failed TPS.
Hopefully, some diagnostic info will be able to be mined.
 
concours said:
I intend on a post mortem, of the failed TPS.
Hopefully, some diagnostic info will be able to be mined.
Click to expand...
Can you tell me the part number of yours? There is a chance they are same on my bike and perhaps I could slap it on just to see what happens...
 
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Got set back up with the droid OS, paid the tithings, bike back together, a few little wiring jobs I'd been meaning to do. Just need to set the TPS value when I get some clear weather.
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Welp. looks like my Bonneville is still giving same flutter at steady state throttle after replacing the TPS. So that's been a waste of $200 :-(
 
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