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Thread: XB12S Running Rich and Won't Idle

  1. #11
    Senior Member
    Join Date
    Sep 2010
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    2,194
    Overall, the o2 sensor is not being "used" during open loop mode, however based on the signals sent by the o2 sensor during closed loop, the AFV gets adjusted. Your closed loop is very lean, or at least the o2 sensor is showing lean conditions to the ECM, then the AFV increases.

    The AFV acts as a multiplier to the FULL fuel map which can result in very rich conditions if the o2 sensor is at fault and not actual running conditions.

    (I think I should've been clearer in my post earlier and thanks to DualSportDad for his post!)

    Onto the injectors - if they are "clogged" will that affect the amount of time they are "open" by sticking - or is that another issue. I'm no expert on injectors....

  2. #12
    No worries Sirius, your explanation for how the ECU compensates fuel adjustments based on O2 readings makes perfect sense as the concept is the same on cars.

    I ended pulling the fuel rails/injectors this morning as I knew it would only take about 10 minutes or so (no need to pull the throttle body as the RM says). I'm going to drop off the injectors tomorrow to have them flow tested and cleaned.

    I'm probably going to go ahead and order a new O2 sensor as it wouldn't be a bad thing to have an extra lying around (I'm a Buell parts whore). I rather wait for the injectors to come back before I put in the O2 as I want to confirm what fixes and doesn't fix the condition. I'll update the forum when I get the results. Thanks for the responses guys...

  3. #13
    UPDATE: FIXED!!!

    So got the injectors back today and although they were slightly "out", they obviously weren't the issue with the numbers I received. RC Engineering confirmed the injectors were 300cc… the front injector was spraying 295 (designated rating as 'good'), and the rear was spraying 283 (designated rating as 'fair' ). After the cleaning, they measure a perfect 300. Although this won't fix the runs rough condition, it will only make the bike run better/smoother in the long run.

    On to the next try… I decided to order a new TPS sensor this weekend after seeing a few You Tube videos online of a Buell that had a similar condition as my bike. Installed the sensor and did a quick TPS Reset, and PRESTO! She runs smoother than she ever has and I haven't even put a few miles on it yet (which usually results in an even better idle and drivability).

    I'm pretty hammered with work the remainder of the week and so I'll test drive the bike this weekend and adjust idle (as I only did a quick TPS Reset) and report back.

    Thanks to everyone on here that gave their input.

    Time to get back on the road….

  4. #14
    Junior Member
    Join Date
    May 2014
    Posts
    22
    This sounds very similar to what I'm experiencing. Can you confirm the following?

    - Engine starts but stops after about 10 or 15 seconds
    - Engine idles around 1000 rpm and even after it warms up, can stop as the bile approaches traffic lights
    - Puffs and coughs at low revs in 1st gear as it pulls away from lights
    - Smells strongly of exhaust fumes after a ride

    I've just bought this bike so learning every day. It has about 21,000km on the clock, stock exhaust but has a K&N filter and the intake modification. Any help and suggestions are much appreciated.

    BTW, any Buells in Melbourne, Australia?

  5. #15
    Hey Anthony,

    Need to confirm exactly what is wrong with the bike:

    You’re saying that the bike can be taken out and ridden on the street, but it occasionally stalls while warming up and when coming to a stop at a light?

    When you say it the bike smells of exhaust fumes, do you mean it smells of unburnt fuel?

    I’d begin by pulling the spark plugs and checking the condition… I’m guessing they are black and you’re suffering a rich condition.

    Have you done a TPS reset since getting the bike?

  6. #16
    Junior Member
    Join Date
    May 2014
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    22
    Yes, it won't idle when cold. Just cuts out. When it warns up it will idle but when approaching a stop, the engine revs sometime drop below 500 and the engine cuts out. Did a TPS reset but not much improvement.

    When it's running, there is a strong smell of unburnt fuel in the exhaust - running way too rich it seems. Below 2500 rpm, it will backfire or cough (not sure which yet) but it runs well above 3000 rpm. Spark plugs are likely fouled but probably as a result of running rich. It need to pull the over the weekend and have a look.

    I'm going to drop it into a Harley dealer for a checkup and service. I'll learn more from them and possibly sort out the problem, too. Thanks for your help and any other observations are most appreciated.

  7. #17
    I'd definitely recommend pulling a plug before bringing it into the dealer. You could have helped/corrected the issue when doing the TPS reset but the plugs were already fouled due to the rich condition. It's a long shot, but it's not a bad idea to see how bad they looked.
    It's also not a bad idea to pull the air box and filter off and check out the interior of the throttle body. It's possible you have some buildup around the throttle plate causing it to stick… if so, get some carb cleaner and give it a good cleaning. Again, this is just another thing to check out.

  8. #18
    Junior Member
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    May 2014
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    Thanks for the advice. Will do.

  9. #19
    Sorry for trolling this site. But, I'm looking for answers to the your same issue? Did you ever get a resolution?

  10. #20
    Banned
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    May 2014
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    Possibly the intake valves are covered by dirt and can not totally close the gap so fuel mixture blows back in the intake through the gap. I used seafoam to clean the engine, no idle and O2 sensor issues anymore.


    Last edited by TPEHAK; 11-14-2016 at 07:24 PM.

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