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Thread: XB misfire at constant RPM cruising (~3500 RPM).

  1. #21
    Senior Member nicholas900's Avatar
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    Quote Originally Posted by Chicknstripn View Post
    Excuse me for being the old grouchy guy in the room but I HATE the fact that half the threads in this forum turn into this nonsense.
    ^ Agree. Pretty gay. Lord of the flies shlt. High school shlt. Facebook shlt. I don't get it.

  2. #22
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    Well after a new fuel pump, new injectors, a $240 trip to a mechanic who "fully seated 1 fuel injector" and then the extra ground I unfortunately have to say it still runs like **** at about 3500 rpms. What's next, i don't know but I am open to suggestions. I can reset the the TPMS and it might run better for another 2 or 3 rides but then it will be back. It's sad because I really like riding this bike when it runs right which is not as often as it should be.

  3. #23
    Senior Member GregoXB's Avatar
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    Quote Originally Posted by Darin View Post
    Well after a new fuel pump, new injectors, a $240 trip to a mechanic who "fully seated 1 fuel injector" and then the extra ground I unfortunately have to say it still runs like **** at about 3500 rpms. What's next, i don't know but I am open to suggestions. I can reset the the TPMS and it might run better for another 2 or 3 rides but then it will be back. It's sad because I really like riding this bike when it runs right which is not as often as it should be.
    I'm sure you did already but did you clean the IAC and the throttle body? And I mean CLEAN. Take off the velocity stack, twist the throttle and open the butterfly valve and get yourself some throttle body cleaner, spray it on a long, soft flexible brush and do a proper cleaning.

  4. #24
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    chickn and Nick900,

    I agree wholeheartedly how some of the threads get WAY off track. I attempted to use satire as a tool to help diminish this trend, as well as try some humor to lighten the whole conversation. You might review your comments in light of that.

    Opto

  5. #25
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    Note: xb12Ss with 35,000 miles. So original seals were well used.

    Darin: Sorry to hear that. What you did matches my work. Yours actually looks a little cleaner.

    I do not know what sensors are matched with ground A and which are ground B (see diagram I attached earlier). Or if ground A and B are connected. Perhaps your issue is with the "A" ground. But before hacking into the harness again, you can test. Before I hacked my harness, I stuck a very fine sewing needle into the terminal from the top side and made a temporary ground from the needle using alligator clips. I had to use wire cutters to get the right needle length (sticks out of terminal but is cleared by the seat). It was not 100% but the bike ran better - enough that I figured it was worth trying the extra ground. I put a drop of rubber cement on the hole when done.

    In all of my research, i did learn two interesting things that might be affecting you:
    1) The seals on the intake (throttle body) are known to fail and allow air to slip in. When my throttle body was pulled (replace the entire throttle body), the streaks on the head were visible where air was being sucked in. This would cause a lean condition. One of my hypothesis was that I had a vibration related air leak causing a lean condition and then the computer freaking out. Obviously, there was a ground issue but I cannot rule out the possibility that I also had an air seal issue.
    2) Apparently, the coils can fail intermittently. You noted new plugs and injectors. Coil is easy to change and not terribly expensive.

    Also:
    3) TPS sensors can develop dead spots (all tps sensors, not just buell). In 24 years, I have replaced 3 TPS sensors on my firebird. A TPS in general should read 0.5 to 5 V from off to WOT. And it should be a linear with throttle. In the case of my Firebird, the sensors would fail in the just off idle range where you tend to have the throttle when cruising (i.e. largest percentage of time). Try measuring the output voltage and look for a dead spot. Go REALLY slowly and look for places where the output fluctuates faster than your hand.

    I hope this helps...

    Note: xb12Ss with 35,000 miles. So original seals were well used.
    Last edited by moarant; 08-12-2018 at 08:58 PM. Reason: added information

  6. #26
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    Plugged in the ECM spy and snapped a couple screen shots as this bike is new to me along with the ECM spy software the only thing I know how to do with the software besides seeing what is going on is reset the TPS. I don't know how much this matters but the previous owner sent out the factory muffler to someone who modified it.

    Buell1.jpg

    Buell2.jpg

  7. #27
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    I added an extra wire to give better ground to ECU but surprice surprice, no significant change. Still stutters, and backfires. Maybe little better when hot, but...

    Next I clean the throttle body.

    Previous owner did mess with the original ECU program and put in Twin Motorcycles software for open air box and Jardine muffler. K&N filter is still on but with the original muffler. I bought a Buell-tooth and I have to study it before I mess up my bike so bad that it would not even start.

  8. #28
    Senior Member GregoXB's Avatar
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    I was amazed at how much better my bike ran after I cleaned out the throttle body.

    I used a long wire bottle brush sprayed with TB cleaner to loosen the tough soot. I trimmed down the bristles with a scissor till I liked the length. Then I took a small piece of microfiber cloth sprayed in TB cleaner, wrapped it around the tip of the brush and secured it with a zip tie, so as not to lose it in the throttle body. I removed a substantial amount of soot. Then I cleaned the IAC with carb cleaner sprayed onto a microfiber cloth. The tip of the IAC was coated in soot.

    The bike came alive after the cleaning. It was like it got a whole new set of lungs.

    You have to remove the velocity stack and zip tie the throttle tube to the brake lever to keep the butterfly valve open while you do the job.

  9. #29
    Senior Member lunaticfringe's Avatar
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    Quote Originally Posted by Darin View Post
    Plugged in the ECM spy and snapped a couple screen shots as this bike is new to me along with the ECM spy software the only thing I know how to do with the software besides seeing what is going on is reset the TPS. I don't know how much this matters but the previous owner sent out the factory muffler to someone who modified it.

    Buell1.jpg

    Buell2.jpg
    in all likelihood either a faulty ecm or your TPS unit going bad. link below and go to 2.2 section and beyond. shows simple voltage test for TPS unit done with multi-meter. another simple TPS test is by checking its ohms with multi-meter. i tested a new 2007 TPS unit years ago and supplied the ohms readings on here for board members. simple test anyone can do and well worth the effort prior to replacing it. your symptoms point to the above. here's the test in OHMS:
    BUTTERFLY FULLY CLOSED IS APPROX. 560 OHMS-----BUTTERFLY FULLY OPENED INCREASES INCREMENTLY TO 3.82 KOHMS.

    and here ya go...
    http://www.ukbeg.com/pash/2008%20Bue.../99493-08Y.pdf



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