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Thread: buelltooth questions

  1. #1
    Member evilokc's Avatar
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    buelltooth questions

    i normally use the FB page but some jackhole hacked my acct and posted something that went against standards and i got locked out for a month. i dont even know what the post was so if you saw it and it sucked sorry. it wasnt me. anyway. my 07 xb12r when running up to redline in a hard accel broke up violently. when the RPM dropped back down it ran fine. i thought i had hit the limiter by mistake. honestly ive hit the limiter on other bikes and its never been a violent back firing thing. however knowing the buell is the caveman of sport bikes i wrote it off. a day or two later the same issue happened but i wasnt close to redline. i was accelerating hard but it was in the 5ks when it broke up. still started, ran, rode fine. the third time it happened was a slightly different story. i was accelerating hard and it broke up violently at about 5500RPMs and the bike died. i pulled the clutch and tried starting it while coasting but it was all crank and no fire. i ended up pushing the bike home about a mile at 5am. glad its light. my initial thought of this being a limiter were removed sice the limiter shouldnt kill the bike and certianly wouldnt stop it from starting back. hours later i checked and it fired right off and ran fine. i dont trust it now. i purchased a buelltooth and fuel pressure test gauge. i was expecting the afv to be high (130%-150%) showing the pump was probably getting weak. however the afv was 99.5%. so at some point the bike thought it was a touch rich. from what i read 99.5% is still in spec but i changed it back to 100%. today i did some live data recording and it dawned on me that i dont know what the normal values are. i was told i may need to check my crank position sensor. i havent hooked up the fuel pressure gauge yet. any imput from the brain trust would be appreciated. oh and if any of you have experience with the rev limiter and know whether or not its violent and shuts the bike off let me know please. doesnt make any sense that it woud shut the system down for an hour plus though. thanks guys.

  2. #2
    Senior Member Cooter's Avatar
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    Your description sounds to me like you have fuel but are losing spark or spark timing at high load or vibration. Lack of re-start also sound like it losing spark. Too bad you didn't test anything while the problem was there.
    Check with carb cleaner in the intake during a no-start time. If it starts check fuel, if it still doesn't check spark.

    AFV +/- 15% is the ECM effectively doing its job, leave it alone.
    Anything outside 85-115 is a engine/ sensor issue. FIX that issue, before screwing with the tune and causing yourself more issues than you have now.
    AFV doesn't affect Open Loop, as in during WOT operation*
    AFV (and EGO) take some time to adjust, and therefore may not reflect a lean condition from a fuel pump or spark issue.
    Whats the EGO Corr value? Should also be near 100.
    NO, rev limit intervention is not violent, should not back fire, and doesn't kill the bike for an hour.
    Rev limits change according to parameters like temperature. You can find them under "RPM limits" using ECMDroid and the Buelltooth you bought.
    Your engine should run fine at ANY RPM for extended periods as long as it is below that limit.

    Or ignore all that confusion and just look at the freaking basics. Wanna play mechanic? OK, these are simple machines. Fuel, air, and timed spark is all they need to run perfectly.
    Hows the coil? Spark plug wires? Coil/wiring? CPS/wiring? (they like to fail with temp, check with a heat gun).
    Your fuel gauge tester thats on the way will only show at rest, tee one in instead and check under load/ while it has an issue. 49psi rock solid at idle or WOT.




    *Simplification warning

  3. #3
    Member evilokc's Avatar
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    i checked the plug wires. they and the coil pass the visual inspection. nothing was loose or damaged. that doesnt mean the coil isnt failing. i havent checked the cps yet. the symptoms do fit with it. ive never heard of testing a cps with a heat gun. do you start the bike and heat the sensor with the gun to see if it causes the issue to appear? i liked the T in fuel pressure gauge idea. when the bike wouldnt start it was very early in the morning and i had to get ready for work.i was pissed at it for making me push it. didnt even dawn on me to check anything at that point. i was data logging this evening on the buelltooth and while sitting at idle for about 5 minutes the bike shut off. it was abrupt enough that it made me think spark not fuel. it did start back and i didnt have to push it which made me happy. now if i can find where ecmdroid hid the data log i could check it out.
    Last edited by evilokc; 09-13-2021 at 02:22 AM.

  4. #4
    Member evilokc's Avatar
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    i removed the front pulley cover and checked all of the plugs under there. i got side tracked momentarily when i found a large wire that appearedd to be a ground not attached to anything. after tracing it turned out to be the exhaust valve wire which has been disconnected. i checked the neg battery cable and the grounds that attach right near the battery. they were good. i visually inspected the ground at the steering head on the lower tree. i plan to remove it tomorrow and give it a good check and reassemble. would be nice if it were just the ground wire. i also read that you can run a thick wire from the neg battery terminal to the head bolt and if there is a ground issue this will resolve it.

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    Did your check engine light ever come on? I had what sounds like a similar issue. Started/idled fine, but would sputter/backfire at higher rpms. It would happen at almost exactly 5k rpm every time, and the third or so time backfired and died. It threw a code the time it died and that's what confirmed the timing sensor for me. Not sure if there's a better way to diagnose this, as it's nearly a $200 part, so you wanna be sure.

  6. #6
    Senior Member Cooter's Avatar
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    Theres no amount of "visual inspection" that prove an electrical connection or part is good or not.
    Test stuff. Have a plan.

    Or

    Be frustrated, spend needless money, and take extra time ****ingaround.

    Your choice

  7. #7
    Member evilokc's Avatar
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    nope. never thrown a code.

  8. #8
    Member evilokc's Avatar
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    a visual inspection can tell you if a wire is broken or a connection is loose. i agree it needs to be removed and checked and said as much. im hoping it will be something as simple as a ground. as far as ive found so far there are only the two main ground locations on a firebolt. im going to check the manual to confirm though.

  9. #9
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    I will add that if you're lucky enough to have someone with a spare timing sensor that is known to work and will let you borrow it (like I was), it's not difficult to replace. Just exepensive. Do what cooter said first.

  10. #10
    Member evilokc's Avatar
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    okay all known ground have been removed cleaned and replaced. no change. timing cover has been removed. someone has been in here already because one of the screws was stripped. jerk. drilled it out. the cps isnt melted. im going to move onto a closer inspection of the coil now.



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