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Thread: High AFV and lean popping on Decel

  1. #1
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    High AFV and lean popping on Decel

    Bought a 32,000 mile XBX12X and going through a ton of troubleshooting to get it fixed.

    2006 XB12X with the Buell Race exhaust, brand new KN filter.

    The bike was down on power, popped like crazy on decel, and had AFV in the 114% range.


    I reflashed it with a proper race tune.
    Also replaced:

    Spark plugs
    Intake seals
    New fuel pump, filter, hoses, pressure regulator
    Injectors cleaned

    Plugged open nipple on throttle body
    Many TPS resets
    Checked the throttle plate rod isn't broken

    It was running great for a little while after the fuel pump replacement last month, and then the AFV started creeping up again to 115%.

    I have not replaced the Oxygen sensor yet because it looks like a massive pain in the ass, but I have one ready to go in.

    Is there anything else I can try or test?

    Currently the bike wonít even really run if I set the AFV to 100
    I should probably get a log recorded as well, but I don't know what to look for.

  2. #2
    Senior Member 34nineteen's Avatar
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    Quote Originally Posted by tacopwr View Post
    Bought a 32,000 mile XBX12X and going through a ton of troubleshooting to get it fixed.

    2006 XB12X with the Buell Race exhaust, brand new KN filter.

    The bike was down on power, popped like crazy on decel, and had AFV in the 114% range.


    I reflashed it with a proper race tune.
    Also replaced:

    Spark plugs
    Intake seals
    New fuel pump, filter, hoses, pressure regulator
    Injectors cleaned

    Plugged open nipple on throttle body
    Many TPS resets
    Checked the throttle plate rod isn't broken

    It was running great for a little while after the fuel pump replacement last month, and then the AFV started creeping up again to 115%.

    I have not replaced the Oxygen sensor yet because it looks like a massive pain in the ass, but I have one ready to go in.

    Is there anything else I can try or test?

    Currently the bike wonít even really run if I set the AFV to 100
    I should probably get a log recorded as well, but I don't know what to look for.

    Wait, so you replaced the intake seals and were cool with that, but didnt replace the O2 sensor because it was a massive pain in the ass? The O2 sensor is much simpler to replace than the intake seals. And depending how you did the intake seals, it would have been even easier to replace the O2 sensor. Hell, when you were replacing the fuel pump it would have taken a few more screws removed to get access to the O2 sensor. Something isnt adding up here.

    How do you know the "proper race tune" is truly a "proper race tune"? Did you get one from IDS or just download one from someone on the internet who "knows what they are doing"? Did you reflash the ECM with the stock tune? Did you check to make sure the fuel pump was putting out the proper pressure? New fuel pumps can be bad out of the box. Did you verify that one of the new hoses isnt leaking in the tank? Did you verify the intake seals are still sealing? Did you check the TPS to make sure its functioning correctly?

  3. #3
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    Yeah, pretty much what he ^^^^^^^^^^^^ said.

  4. #4
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    Tune came from Revision Moto. I dont know what tune was on it previously as I didnt get any info from the previous owner.


    I have not checked fuel pressure with a gauge, but I did run the old pump and confirmed it barely flowed anything. The new pump shot fuel out of the hose perfectly. The bike ran perfect after replacing that and resetting AFV to 100.

    I guess I can redo the intake seals see if anything has changed there, but I tried the brake cleaner test and no change in idle was noticeable.

    TPS has been reset a few times. It ran great after the last one at temperature, but over the past few weeks the bike started running worse and the AFV went back up.

    I guess Iíll just go through everything again. Only so many things it could be, right?

  5. #5
    Senior Member 34nineteen's Avatar
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    Maybe the fuel filter on the fuel pump clogged again due to debris/contaminants in the tank. Maybe the engine temp sensor is malfunctioning? Maybe the IAT is? What is the voltage on the O2 sensor? I'm assuming you checked it and verified it was bad before purchasing a replacement? So many variables.

    I'm still baffled why you think its such a pain the ass to replace the O2 sensor, after doing all that work (and being willing to go back through it all again). Its only 9 easy steps documented in the service book.... ohhhh, thats it.

  6. #6
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    Lol goddamn you guys are hot about the oxygen sensor. I do have the service manual.
    Iíll swap that out this weekend after I get the bike hanging from the rafters again.

    Iíll double check the engine temps are correct as well. They were reading correctly last month but who knows now.

  7. #7
    Senior Member 34nineteen's Avatar
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    OK, dont replace the sensor then. Do whatever you want.

    PS. Having the service manual and actually reading it are two separate things.

    Here is your award. Sorry the problem wasnt easier to solve.

    Last edited by 34nineteen; 10-21-2021 at 08:01 PM.

  8. #8
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    Dayum dude what is with your tone?

    I bought the oxygen sensor after doing hours and hours of other work. Sorry I didn't install it immediately, when it requires that I hang the bike from the rafters to remove that shock. Itís not the most convenient thing in the world, and requires a bunch of time. I was simply asking for any advice for things I might have missed.

    PS I did read the manual.

  9. #9
    Senior Member 34nineteen's Avatar
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    You're absolutely right. Dont do it. Its not worth your time. Or anyones for that matter.

  10. #10
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    I hope you make it out of your momís basement one day. Get a fukking life.



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