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Surging?

Old May 12, 2021 | 06:08 AM
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Default Surging?

Have a 15 SGS with stage 1. Running a FP3 on it with new bars installed 3 years ago.

Last week went on a ride and after about 70 miles (bike running great) pulled over for a quick break. Started back up and almost immediately the bike felt like it was surging as if it was giving more throttle (maybe a 100 rpm or so). Pulled over a mile later and looked things over real quick and didn't find any glaring issues. Continued on for another 15 minutes and it was still doing it but not as bad. Grabbed lunch and bike sat for a good hour probably more. Ran another 2 miles for 1 more quick stop and problem was still there, again not too bad, but still surging. After the last stop continued on for another 100 miles give or take and no issues. Bike was running as it should. During this ordeal no codes where thrown.

Not really sure where to start looking. At first I thought gas, maybe fuel filter but if was not getting gas I would assume the bike would lose power not gain. Again just looking for some suggestions.

Thanks
 
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Old May 12, 2021 | 06:17 AM
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- Are you letting bike idle for a bit before shut-down?
- Is TB connector secure/clean?
- How many miles on bike?
- Define your "surging" issue...e.g at idle bike's going fm 800-to-900-800 rpm in a constant pattern, or just running 100 rpm higher than norm?
- Have you disconnected FP to see if it corrects the issue?
 
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Old May 12, 2021 | 06:27 AM
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Maybe lost the purge tube cap? (90383-98) Look on top of the throttle body, and see if the rubber cap is still on the purge tube (#11, seen here).
 
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Old May 12, 2021 | 06:42 AM
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Originally Posted by rigidthumper
Maybe lost the purge tube cap? (90383-98) Look on top of the throttle body, and see if the rubber cap is still on the purge tube (#11, seen here).
That's what I'm thinking as well. I've seen it a time or two.
 
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Old May 12, 2021 | 07:09 AM
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Are you letting bike idle for a bit before shut-down?
- Is TB connector secure/clean?
- How many miles on bike?
- Define your "surging" issue...e.g at idle bike's going fm 800-to-900-800 rpm in a constant pattern, or just running 100 rpm higher than norm?
- Have you disconnected FP to see if it corrects the issue?

I honestly don't remember how I shut the bike down. I assume no different then I normally do.
The TB is secured have not pulled yet to see if it needs cleaned (will clean anyways when I pull it)
17,500 miles on the bike (bought the bike new)
Surging goes from about 1600/1700 up about 100 RPM for a split second and back down. Did it every minute or so. Bike Idled fine.
Purge Cap is still on
I have not disconnected the FP yet since I have not rode since the issue (beautiful Ohio weather). But that was on my list to try.
 
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Old May 12, 2021 | 10:57 AM
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Especially if your crank case vent tubes are still in the factory configuration, try cleaning your MAP sensor as it may be fouled with condensed engine oil. Fuel and air filters are always possible causes of erratic engine operation. Has the machine recently been in a heavy rain or washed with a garden hose or high pressure washer? Remove the spark plugs and see what shape the firing tips are in also.
 
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Old May 12, 2021 | 02:13 PM
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There was something on this a couple of months ago. If the throttle is open just a tiny bit (hand resting on and causing the throttle to open) and it's shut down the ECM and associated sensors pick up on this and tries to find the shut down rpm vs. the scheduled idle. To reset the throttle position sensor, turn on Ign. for 10 secs and off for 10 secs X 4 times. Hope this helps.
 
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