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Buell Forum » Big, Bad & Dirty (Buell XB12X Ulysses Adventure Board) » Weird breakup at high speed - high RPMs « Previous Next »

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Tempest766
Posted on Tuesday, August 07, 2018 - 08:58 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

noticed something weird today. power loss at near WOT going about 80 at just over 4000RPM. backed off on the throttle a little bit and it accelerated again. TPS was recently calibrated (a couple of weeks ago) with expected results.

What are some common causes of breakup at higher speeds and extreme throttle?

IDS racing ECM. My old stock ECM started doing this right before it crapped out, but got really really bad over a couple month period, before finally dieing.
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Ourdee
Posted on Tuesday, August 07, 2018 - 10:47 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Heat and skip spark mode.
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Tempest766
Posted on Tuesday, August 07, 2018 - 11:39 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Good guess, but engine is running quite cool now: cool enough that the fan quits running if I pull over.
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Smorris
Posted on Wednesday, August 08, 2018 - 10:52 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

if it were carbureted, that would indicate too rich of a main jet. so since the last thing fiddled with was TPS maybe the problem. only a guess
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Natexlh1000
Posted on Wednesday, August 08, 2018 - 11:57 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Someone on the 1125 side posted similar symptoms and after lots of debugging, it came out that the air filter was clogged up.

Is the tank breather still breathing?
Those idiot wasps like to block tubes with mud.
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Tempest766
Posted on Wednesday, August 08, 2018 - 07:23 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Hmmm...TPS reads correct values when hooked up to a meter. I do probably need a new air filter. Couldn't hurt regardless...wish I could get the K&N locally. I frackin hate online buying.
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Tootal
Posted on Thursday, August 09, 2018 - 10:29 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

When you zeroed the tps was the engine hot? IF not you might try it since it's so easy on a 2008.
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Tempest766
Posted on Thursday, August 09, 2018 - 01:16 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

@ tootal --- yes yes yes...hot engine and used iso alcohol and q-tips to clean the butterfly and the inside of the throttle body intake before taking the bike for a spin to heat up the engine.
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Tempest766
Posted on Thursday, August 09, 2018 - 04:54 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Of course when I do my performance testing I always have optimal weather so the test case is never valid. Today is cool and dry and the beast has always run better in cool/dry weather. so anyway, I removed the air filter, left the air box cover open, and went for a ride. At 90mhp and WOT it was still pulling strong and the engine didn't heat up. I went home and put the plastic back on (still no air cleaner) and went for another ride. This time there was some power loss in the upper end and the engine was running hotter than on the first ride.

It seems that once the engine heats up it doesn't cool back down, but as long as you keep moving from starting with a cold engine it doesn't heat up in the first place. This has always been a problem with this bike. I'm fine until I get stuck in PA road construction or city stoplights. After that it runs like a dog until it is shut off and the engine fully cools down. Then it's a screamer again.
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Steveford
Posted on Thursday, August 09, 2018 - 05:24 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Try taking a look at your IAT reading, does it seem normal?
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Scottykrein
Posted on Thursday, August 09, 2018 - 06:33 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Have you relocated your ecm? Read up on those symptoms. Bike gets hot, seat sags enough to put pressure on the ecm. Cracks can be almost invisible.

I had this issue, turned out to be a failing tps. You can check it on ecm spy, when you turn the throttle the bar graph should move super smooth with no lag.
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Tempest766
Posted on Friday, August 10, 2018 - 12:52 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

@steveford - gonna check the IAT sensor tomorrow

@scottykrein - been through 3 ECUs. HD stealership butchered the underside of the seat to supposedly fix that problem...it did not. Third ECU is in original location but I've added a block above it to add another 1/2 inch of space and keep the seat from hitting the connectors. tested connectors by putting play-doh on top of them and then looking for deformation after long rides. The seat no longer touches the connectors.
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Etennuly
Posted on Friday, August 10, 2018 - 09:56 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Intake leaks are hard to diagnose with compensating ECMs. But bad intake seals can make it lean out to miss at high rpms, and it will run hot.

What do the plugs tell you? Super clean almost white? Too lean.
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