Fluttering Butterflys - Kawasaki Vulcan Forum : Vulcan Forums
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post #1 of 14 (permalink) Old 06-20-2019, 03:46 PM Thread Starter
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Fluttering Butterflys

On the first ride of the day and with the engine warmed up when I shift into 2d gear, I experience stumbling (for a lack of a better description) as I open the throttle. And I don't mean wide open either. Then after shifting into the higher gears it's gone. At first I just chalked it up to the flash as nothing is perfect. And yes I've cleaned the throttle body. And it doesn't help. There aren't any vacuum hoses off or leaking either. I finally discovered while cleaning the throttle body that as I slowly start to open the throttle slowly the butterflies are fluttering. Quickly slightly closing and they are opening. They aren't opening smoothly. If I wrap the throttle open and closed a couple times, then slowly open the throttle they open smoothly. So, now when I first turn the switch on I open and close the throttle a couple times and don't experience the stumbling as I start riding. So, with great thought and pondering I summarized that it was probably the TPS. I'll just order one and replace it. Well, put a dress on me, slap me around and call me Susan, can't do that. You have to buy the throttle body to get a TPS as they are paired together at the factory. Can't even remove the TPS without taking the throttle body off. I did pull the connector and cleaned the contacts just in case the problem could be there. It wasn't. So, I guess I'm now asking the great minds of members here, what's your guess?

2013 Kawasaki Vulcan 1700 Voyager
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post #2 of 14 (permalink) Old 06-23-2019, 07:29 PM
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I would try lubing the cables. I use boesheild.
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post #3 of 14 (permalink) Old 06-24-2019, 07:12 PM Thread Starter
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Quote:
Originally Posted by oldbeezer View Post
I would try lubing the cables. I use boesheild.
I hope you know that the throttle cables aren't directly connected to the throttle plates (butterflies if you will). All they do is rotate the TPS that sends a signal to the ECU that in turn sends a signal back to the electric motor on the throttle body to position the throttle plates accordingly. As far as dirty cables go, they would have to be actually pinched to effect anything. The throttle return spring is strong enough to overcome any resistance dirty cables could possibly give. I know no one wants to here any derogatory comments about the "flash", but nothing's perfect. Only three possible things that could be causing this. The TPS, the ECU or the electric motor on the throttle body. I suspect the TPS. Just cant replace it.

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post #4 of 14 (permalink) Old 06-24-2019, 11:18 PM
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Originally Posted by Pilot747 View Post
..Only three possible things that could be causing this. The TPS, the ECU or the electric motor on the throttle body. I suspect the TPS. Just cant replace it.
Are you getting a code 11? Measure the voltages as shown. I bet it is your flash... or... some other sensor like water temp, influencing your ECU.

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post #5 of 14 (permalink) Old 06-24-2019, 11:54 PM Thread Starter
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Yeah, forget to mention, no code. That would narrow it down considerably. I don't believe it's some sensor somewhere in the system though. I've watched the throttle plates opening erratically through about 1/4 throttle movement slowly, with the bike cold. After opening and closing the throttle quickly a couple times and watching them again while slowing opening the throttle, they act normal. All this while the bike is cold. After it's been running everything operates normally. It only happens as I move out, shift into second and a little in third. After that everything is fine. I've been thinking about watching maybe Ebay or somewhere for an ECU that's reasonable and swapping mine out and see what happens. Might try and take a video and posting it. That's of course if I can figure out how to post it.

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post #6 of 14 (permalink) Old 06-25-2019, 07:08 AM
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Well sounds reasonable about the TPS, but why only in second and a bit in third?
Why not every gear change?


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post #7 of 14 (permalink) Old 06-25-2019, 07:27 AM
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Quote:
Originally Posted by Pilot747 View Post
I hope you know that the throttle cables aren't directly connected to the throttle plates (butterflies if you will).
No I was not aware of this. Having just bought a '12 Nomad I am still on the steep part of the learning curve. I am of the belief that when trouble shooting/repairing a problem whose cause I am not sure of to do the easy and cheapest actions first. I also feel that more problems are of a mechanical issue rather than electronic. What led me to my suggestion to lube the cables was your comment, "They aren't opening smoothly. If I wrap the throttle open and closed a couple times, then slowly open the throttle they open smoothly. So, now when I first turn the switch on I open and close the throttle a couple times and don't experience the stumbling as I start riding." That sounded to me like a mechanical issue with the cables. When sitting for a while the cables would take a set and wrapping the throttle would free them up. Now might it be possible the tps would see the "jerky" motion of the cables as a signal and send it to the "butterflies"? I am not suggesting this IS the problem, it is probably not but it is a cheap and easy thing to try before replacing expensive bits. I am very interested as to the solution to this problem, I have not experienced it but if I do in the future it would be nice to know the cause.
Jim
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post #8 of 14 (permalink) Old 06-25-2019, 08:27 AM Thread Starter
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I agree. Before the days of all the electronics when computers took over, the cheep and easy fixes usually worked. When I start to move out I usually shift quickly into second. Don't get the big clunk that way. Then as I'm opening the throttle I get the stumbling. In the Carburetor days, the throttle cables were directly connected. Twist the throttle and the throttle plates open.

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post #9 of 14 (permalink) Old 06-25-2019, 10:45 AM
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Quote:
Originally Posted by Pilot747 View Post
Yeah, forget to mention, no code....
Stop guessing and troubleshoot by measuring the voltages. Could save you some $$$.

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post #10 of 14 (permalink) Old 06-25-2019, 12:06 PM Thread Starter
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Not a big problem and I'm not spending money on it. I've always found, this maybe just me that, if your looking for a needle in a haystack, it might be best to first know which haystack to look in. Not a real big problem as I said.
Those voltage readings could be meaningless if the TPS is sending the ECU erroneous data. Might lead you think the ECU is bad when it might just be the TPS. Would be nice to be able to change it.

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Last edited by Pilot747; 06-27-2019 at 09:25 PM.
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