i normally use the FB page but some ******** 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.
buelltooth questions
- Thread starter evilokc
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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
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
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.
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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.
RidetheLightning
Well-known member
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.
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
Test stuff. Have a plan.
Or
Be frustrated, spend needless money, and take extra time ****ingaround.
Your choice
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.
RidetheLightning
Well-known member
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.
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.
DamMechanic
Well-known member
I’ve had coils fail just like that in the past. Should be able to do a ohm’s check to see if it’s in range. You could also test with one of those adjustable spark gap tools you plug into the spark plug wire. A good coil will jump a 3/8” gap.
This check will only be an effective diagnosis during your no-start condition. If the bike is currently running, it will pass all these tests.
All you need is 10 minutes, and test light that Harbor Freight will give you for FREE with a coupon.
1) If you have an extra spark plug laying around for any gas engine you can use it to test for spark, without removing yours at all. Plug your plug wire on it, ground the metal end and crank it. Check both plug wires. If you don't have a plug from your lawn mower, pull out one of yours and use it.
2) If you are getting spark at BOTH cylinders during this no-start condition you can stop looking for electronic reasons (except timing). Look for fueling issues. Does the pump run with the key/kill switch on?
3) If you are not getting spark at BOTH plugs, check the 3 wire plug going in to the coil. Thats the primary/ low voltage side. The wires on each end of the plug fire the coil when grounded. The center wire should be battery voltage. Check the wire on each side with a test light connected to the battery (+) and crank it over. You should get a blinking light on both. If you DO get blinking oil both, get a coil, yours is bad.
4) If you are not getting spark at ONE plug, swap the wires. If the spark changes cylinders, you need coil wires. If it does not, you need a coil.
5) If both wires do not blink, check the center wire of the CPS the same way, if it doesn't blink, and you have input voltage at the plug, get a CPS, yours is bad.
6) If the CPS wire blinks, check it at the ECM. NO blink, its the wire. Yes blink, its the ECM.
7) If you have a blinking wire on only ONE of the coil primary wires, check it at the ECM. NO blink, its the ECM. Yes blink, its the wire to the coil.
Once you finish ALL these very simple checks, IN ORDER, during a no start condition, you will know whats wrong with your bike without guessing and can fix it without spending money to replace parts that are good. 10 minutes. I'll wait.:angel:
All you need is 10 minutes, and test light that Harbor Freight will give you for FREE with a coupon.
1) If you have an extra spark plug laying around for any gas engine you can use it to test for spark, without removing yours at all. Plug your plug wire on it, ground the metal end and crank it. Check both plug wires. If you don't have a plug from your lawn mower, pull out one of yours and use it.
2) If you are getting spark at BOTH cylinders during this no-start condition you can stop looking for electronic reasons (except timing). Look for fueling issues. Does the pump run with the key/kill switch on?
3) If you are not getting spark at BOTH plugs, check the 3 wire plug going in to the coil. Thats the primary/ low voltage side. The wires on each end of the plug fire the coil when grounded. The center wire should be battery voltage. Check the wire on each side with a test light connected to the battery (+) and crank it over. You should get a blinking light on both. If you DO get blinking oil both, get a coil, yours is bad.
4) If you are not getting spark at ONE plug, swap the wires. If the spark changes cylinders, you need coil wires. If it does not, you need a coil.
5) If both wires do not blink, check the center wire of the CPS the same way, if it doesn't blink, and you have input voltage at the plug, get a CPS, yours is bad.
6) If the CPS wire blinks, check it at the ECM. NO blink, its the wire. Yes blink, its the ECM.
7) If you have a blinking wire on only ONE of the coil primary wires, check it at the ECM. NO blink, its the ECM. Yes blink, its the wire to the coil.
Once you finish ALL these very simple checks, IN ORDER, during a no start condition, you will know whats wrong with your bike without guessing and can fix it without spending money to replace parts that are good. 10 minutes. I'll wait.:angel:
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RidetheLightning
Well-known member
FYI my CPS didn't look melted, and the cover is secured with rivets, so someone's already been in there. Should probably set your static timing in case someone messed with it.
Good point RtL:eagerness: If that cover didn't have its stock rivets in it, you have more things to check after you find the issue. Take a picture of where it is now, but i wouldn't suggest messing with it quite yet. Timing is not causing your problem.
Man, you are a goldmine of information about checking ignition! :eagerness:
:black_eyed::love_heart:
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Barrett
Well-known member
Man, you are a goldmine of information about checking ignition! :eagerness:
Sourced from me. Unadulterated blatant plagiarism. :mad-new::down:
:mad-new:LOL
https://www.buellxb.com/forum/showt...fuel-spark-crank-no-start&p=630917#post630917
Sourced from me. Unadulterated blatant plagiarism. :mad-new::down:
LOL
https://www.buellxb.com/forum/showt...fuel-spark-crank-no-start&p=630917#post630917
He's the Amy Schumer of Buell diagnosis!
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She's so hot:upset:
Hey Barrett, if it's plagiarism, I picked the best source!
:angel:
Or we get basic spark questions SO MANY TIMES!! it feels like Déjà vu. Just blame the part you don't understand. CPS or ECM, right?
Hey Barrett, if it's plagiarism, I picked the best source!
:angel:
Or we get basic spark questions SO MANY TIMES!! it feels like Déjà vu. Just blame the part you don't understand. CPS or ECM, right?
i found the issue. its the coil. i just havent figured out the reason yet. i gave a spark tester that i was using. when i initially put it on i got no spark from either side. went to remove the coil from the bike and i smacked the plug with my wrist when i was reaching in and it flt loose. i unplugged it and then plugged it back in and the bike fired right off. tester showed spark on both sides. so the coil is the issue however its not known yet if the coil is bad or if the issue was with the plug. testing in progress.
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