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Thread: 2003 XB9s wont Rev past 3000 after warm up

  1. #11
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    Quote Originally Posted by Markxb9 View Post
    Re-did tps last night and bike runs great still for 10 - 15 min then it will not rev past 3500 rpm. Problem must be something other than the TPS.
    I still have no codes or check engine light.
    mark: i responded to your PM on this. you either have a failing fuel pump or ecm unit...or both. your ecm is 17 years old and i'm seeing these fail now due to age, over-heating, voltage spikes and extensive voltage drops. in all likelihood it's the reason the bike runs well for 10 minutes then just dies. and the reason you have no active CEL or historical fault codes.

  2. #12
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    Wow, this thread went to hell quickly. Sorry Markxb9, heres some help.
    This a screenshot of the factory manual for a 2006 XB:
    Screen Shot 2019-04-25 at 10.25.14 AM.jpg

    Are you doing EXACTLY this procedure?

    If you are doing that, and getting the correct TPS angle reading at idle afterwards you can safely move on if the TPS sweep is good when tested when the bike is running poorly. i.e. pull over and immediately check it.

    I am intrigued to why you get different lengths of time before it starts running poorly, but if your timing is accurate... it's a clue.

    Buell cold-start programming is very rich and very long. I wonder if you have a big air leak somewhere that the cold-enrichment cycle is masking?
    Go ahead and check the AFV value for another clue, and test for an intake leak. If it's not that, we'll have to stop guessing and jumping around, and do some actual real diagnosis.

  3. #13
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    Looks like Lunatic and I were posting at the same time All hands on deck! I agree with him as well, you could test the fuel pump to know if it's bad before buying that expensive part, I think its odd that its failing so consistently? Dunno, could be, I've seen weirder stuff...

    The ECM could also be a possibility, but hard to test. Glad they're cheap! Maybe someone here has one to borrow? Save your program, install on spare ECM and give it a shot.

    Since we're guessing, the CPS is a sensor that will fail with heat and could definitely cause this symptom, exactly this way. You can use a hair dryer to test it, but they are cheap enough to throw $ at it and replace anyway.

  4. #14
    Senior Member rb70383's Avatar
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    Lunatic you're right about aging electronics...

    Had a 96 neon. Would run almost 5 minutes exactly. Always would die within 3-5 seconds everytime. No codes. Ended up being a bad crank sensor. could be aging sensors.

  5. #15
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    Bad crank sensor? Like a CPS? Hmmmm. LOL

  6. #16
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    Quote Originally Posted by Markxb9 View Post
    Re-did tps last night and bike runs great still for 10 - 15 min then it will not rev past 3500 rpm. Problem must be something other than the TPS.
    I still have no codes or check engine light.
    The cam position sensor is one of the very few things that can (do) fail with no error codes showing. It *IS* and 03, so it's the cheaper CPS to just replace it and be done. I've had this happen to me personally a few years back, research took me through Badweb to find the answer. http://www.badweatherbikers.com/buel...tml?1362582842

  7. #17
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    Thank you everyone for the help and suggestions. I am still trying to resolve the problem. I am going to try and check the TPS and CPS sensor before I move to the ECU
    I think i will also try a full re-flash. It does not seem likely that its the fuel pump.... It really does feel like after the warm up the rev limiter is reduced to 3500

    I have had 10 bikes and never been stock like this before. so thanks again for the help.

    cheers

  8. #18
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    If you're gonna guess, a CPS is hard to diagnose unless you catch it while bad, but cheap and easy to change. I have $2 on that

    A TPS is easy to diagnose, and you've done that.

    An ECM with a temp related issue would be highly unlikely, without physical damage like a cracked case. Swapping in another program can be free though, make sure to save yours first!

  9. #19
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    Ok update, re-flashed the ECU last night and did a TPS reset. bike started great. Ran for 15 min and then loses all power above 3000 RPM again.
    However I now got a few error codes: 15 Air Temp too High / short to ground 33 fuel pump short to ground.
    I checked batt and everything is tight. i unplugged and checked the connections to the air box temp and fuel pump. Went for another ride. same problems remains.
    and only Code 15 came back as a current error??????

    Second Note 2003 does not have Crank Position sensor like the later models.....would the cam position sensor cause this issue after warm up or
    going into open loop
    Last edited by Markxb9; 05-02-2019 at 08:25 PM.

  10. #20
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    My bike is a little odd....there is no ground at the steering neck i took all this apart a while ago and nothing attached to head stem but previous owner has added extra grounds running back to the negative on the batt and the coil and has had an extra ground added to it.... I went through all the grounds and cleaned and re tightened. as per the write ups that I have read. But I will try and go over them all again. before I order a new cam sensor then ecm followed by fuel pump
    this is starting to add up.... I wish there was a trusted shop in my area that works on buells



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