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Thread: XB12r with poor running past 1/4 throttle

  1. #1
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    XB12r with poor running past 1/4 throttle

    I have looked at several other posts with this title and doesnt seem to apply to this bike. I am a very experienced tech, but no buell experience. Bike starts fine, idles a little rough and when you nail the gas it bucks and hiccups then clears out intermittently and will run up to redline. Does it all the time, not intermittent. Here is a list of the new parts; Fuel pump, tps, cylinder head temp sensor, o2 sensor, crank sensor, coil, plugs, coil wires, fuel injectors, air temp sensor. All oem parts. ECM spyware installed and tps reset procedure performed 3 times. Intake manifold seals replaced, no sign of air leaks. Ran some additional grounds into the harness. Battery and cables good, no corrosion, cylinder head ground strap clean. Need a direction to move in. on a side note, its the first fuel injected bike i have worked on without a map/barometric pressure sensor. Seems odd it doesnt use one.

    any suggestions would be appreciated

    thanks

    dave

  2. #2
    Member TapRoot's Avatar
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    What year bike, race or stock ECM and just out of curiosity, what is your AFV at? Also,what is your idle set at including degrees (ecmspy)? What type Of plugs are you using? Did you perform tps reset when the bike was at running temp? Is your throttle bottle boot pushed all the way down and sealed, you should be able to run your finger inside and feel it butt up flush. FWIW you canít just crack the throttle WFO from idle without a little hesitation from my experience, then again Iíve only owned a Buell for just over a year and though I do all my own work as a part time home brew wannabe poser mechanic Iíve been able to accomplish every task through this site. Gurus will be chiming in to help.

  3. #3
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    What are the mods on the bike ?
    What is the elevation where you live ?
    Was it doing this since you first got it ?
    Last edited by njloco; 08-09-2019 at 01:16 PM.

  4. #4
    Senior Member Cooter's Avatar
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    Your Fuel Injection system doesn't need a Baro sensor. It reads what the engine is putting out via the O2 sensor so it doesn't need to know what the air density is*

    *Unless you are running an Open Loop tune that isn't referencing your O2, then you will need a baro sensor for a fuel multiplier.

  5. #5
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    I may have posted this in the wrong forum. its a 2005 xb12s lightning. Stock ecu, stock muffler, elevation 4200 feet. I did not do the tps reset when engine hot, did it engine cold. I'm helping a friend with this project. Its not a slight hesitation, its a huge running issue.

  6. #6
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    did tps reset hot, didnt fix anything. problem gets way worse as it heats up. On Ecm spy the VSS shows and input all the time running or not. tried disconnecting voltage regulator and stator, didnt change anything. set tps at 5.5 degrees idles was at 950rpm, raised it to 1100 which brought tps to 5.8. played around from 5.2 to 5.6 and it didnt change anything. velocity stack is flush and fully seated.not real sure how to get the afv reading. Possible vss sensor?

  7. #7
    Senior Member Cooter's Avatar
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    Obviously there's been no diagnosis work on this. That explains the very long list of new parts...

    First step is to diagnose it. If you KNOW the part you are replacing will 100% fix the problem, thats diagnosis. Everything else is guessing.

    You need fuel, air, spark. First step is to determine which one of those systems is not working well. I would get a free copy of ECMDroid from the GooglePlay store, and a Bluetooth dongle (I like mine from Buelltooth.com). Then your android device (phone) can communicate with the Buell ECM and tell you almost everything you need to know to diagnose it properly.

    Once you do that look at the AFV. That number will tell you what the ECM is trying to do to compensate for the issue you are having.



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