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Thread: Engine Fluttering Sound

  1. #71
    Commuter Extraordinaire Engine Fluttering Sound
    Engine Fluttering Sound
    SergeantChuck's Avatar
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    Quote Originally Posted by rippin209 View Post
    Is the problem something you can hear or do you have to be there in person to feel something is wrong?

    I'm sure your tired of spending money on parts but have you changed the oxygen sensor that's on the air box?

    When mine went bad I don't remember it throwing a code, anyone else know a way to test the oxygen sensor?
    You can hear it and fell it. That's where the whole flutter title came from because I don't know how else to explain the sound. It reminds me of how an 8 cylinder engine sounds when running on 6 - 7 cylinders. It just sound off. You can definitely feel it. The entire engine shutters when you put it under a heavy load. If you ease into the throttle, its not so bad. It IS ridable but you cannot accelerate hard.

  2. #72
    Senior Member Jt105's Avatar
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    My neighbor’s Suzuki twin kinda acted like that. He rebuilt carbs, changed plugs, chased the issue for months. Turned out one cylinder had a cracked ring.

    JT

  3. #73
    Super Moderator Engine Fluttering Sound 670cc's Avatar
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    Quote Originally Posted by SergeantChuck View Post
    This is the most recent list of things I have tried. I already replaced what I called the mass airflow sensor in the top of the air box.

    1. Checked Oil Level
    2. Replaced Spark Plugs
    3. Replaced Air Filter
    4. 3 X Tank of fuel with Seafoam
    5. 1 X Tank of fuel with HEAT
    6. Replaced Ignition Coils
    7. Opened fuel cap while riding to test venting
    8. Checked for loose ground wires.
    9. Adjusted Valves
    10. Removed and cleaned throttle body
    11. Replaced fuel injectors and fuel rail
    12. Inspected both air box gaskets
    13. Conducted compression check @ 125PSI (Test was done wrong) Will retest this weekend
    14. Sprayed starter fluid throughout entire engine area focusing on throttle body region


    I have a busy weekend but I hope to check the compression a second time doing it the correct way and I will clean as many electrical connectors as I can access just for the hell of it.
    Early on in the discussion, the fuel pump was mentioned as a possible culprit. Have you given thought to checking fuel pressure, or do you even have the means to do so?
    Greg
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  4. #74
    Commuter Extraordinaire Engine Fluttering Sound
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    SergeantChuck's Avatar
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    Quote Originally Posted by 670cc View Post
    Early on in the discussion, the fuel pump was mentioned as a possible culprit. Have you given thought to checking fuel pressure, or do you even have the means to do so?
    I do not have the ability to test fuel pressure myself but I spoke with a friend who is more mechanically smart that myself with motorcycles and he mentioned he might have some sort of inline tester that goes between the fuel line and fuel rail. Trying to coordinate that with him. At one point my attention was focused on a potential fuel pressure problem and I even did some research to determine if the bike had a fuel pressure regulator but most of my searches only returned the fuel pump sending unit. Replacing the fuel pump has always been in the back of my mind just trying not to go there quite yet.

  5. #75
    Senior Member Engine Fluttering Sound dduelin's Avatar
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    Get a compression check with the throttle butterfly open as already noted. After that if one or both cylinders are lower than 240 psi or so pour or squirt a spoonful of motor oil in each cylinder and repeat the compression test. If the low value is improved the root cause is likely a piston ring or cylinder wall problem, if the value does not improve if could be valve related.
    Dave

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  6. #76
    Member dreamer's Avatar
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    Never underestimate O2 sensors. It does not have to be dead completely (which would be a better case actually), but it can report false data to the ECU which in turn will send wrong fuel/air mixture because of it. O2 sensor is not there to protect the cat, but to keep the mixture as lean as possible. In closed loop the mixture ratio fluctuates quite a bit, sometimes to the point of making the engine run irregularly. My Honda Varadero was quite jerky at low speeds until I disabled the O2 sensor completely. Made 20000 km after that with cat still in place with no problem whatsoever and engine ran buttery smooth. Mileage did not get noticeably worse either. What happens is you force the ECU to use the default preprogrammed fuel maps. I would try to disable the O2 sensor temporarily just to see how that would change the behaviour.

  7. #77
    Senior Member rippin209's Avatar
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    Quote Originally Posted by dreamer View Post
    Never underestimate O2 sensors. It does not have to be dead completely (which would be a better case actually), but it can report false data to the ECU which in turn will send wrong fuel/air mixture because of it. O2 sensor is not there to protect the cat, but to keep the mixture as lean as possible. In closed loop the mixture ratio fluctuates quite a bit, sometimes to the point of making the engine run irregularly. My Honda Varadero was quite jerky at low speeds until I disabled the O2 sensor completely. Made 20000 km after that with cat still in place with no problem whatsoever and engine ran buttery smooth. Mileage did not get noticeably worse either. What happens is you force the ECU to use the default preprogrammed fuel maps. I would try to disable the O2 sensor temporarily just to see how that would change the behaviour.
    How do you disable the O2 sensor?
    Is it as simple as unplugging it or do you have to do something else?

  8. #78
    Member dreamer's Avatar
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    Just for diagnostic purposes you can simply unplug it. When the ECU finds no signal from O2 sensor it will assume it is faulty and will default to open loop fueling. It will keep reading other sensors and read the appropriate values from fuel maps, so the engine will run OK. You will get the FI light however and error code will be recorded. To eliminate this from happening you would need to fool it into thinking, that O2 sensor is OK just not warm enough to provide any sensible data. Even in normal operation this is happening when the engine is cold, ECU is running in open loop mode until O2 sensor starts feeding it with data. Actually, closed loop (using O2 data) is not used always anyway, but only under low power, e.g. when cruising with steady throttle or when idling. When more power is needed ECU disregards data from O2 sensor and uses other sensors and fuel maps anyway (so called open loop).

    To eliminate error and FI light there are O2 sensor eliminators usualy in a form of dummy connector which replaces the original connector with wiring from the actual O2 sensor. What it is in reality is just a more convenient (and more expensive) packaging for a simple resistor, usualy arround 320 Ohm. If you bridge the correct wires with the resistor, ECU will assume that O2 sensor is alive and kicking, but not ready to provide data and will keep running the open loop without error. At least this is how it worked on Honda Varadero 2009 and probably all other Hondas at the time. NC and newer models may be different, but I doubt it.
    Last edited by dreamer; 16th March 2019 at 10:35.

  9. #79
    Senior Member rippin209's Avatar
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    Quote Originally Posted by dreamer View Post
    Just for diagnostic purposes you can simply unplug it. When the ECU finds no signal from O2 sensor it will assume it is faulty and will default to open loop fueling. It will keep reading other sensors and read the appropriate values from fuel maps, so the engine will run OK. You will get the FI light however and error code will be recorded. To eliminate this from happening you would need to fool it into thinking, that O2 sensor is OK just not warm enough to provide any sensible data. Even in normal operation this is happening when the engine is cold, ECU is running in open loop mode until O2 sensor starts feeding it with data. Actually, closed loop (using O2 data) is not used always anyway, but only under low power, e.g. when cruising with steady throttle or when idling. When more power is needed ECU disregards data from O2 sensor and uses other sensors and fuel maps anyway (so called open loop).

    To eliminate error and FI light there are O2 sensor eliminators usualy in a form of dummy connector which replaces the original connector with wiring from the actual O2 sensor. What it is in reality is just a more convenient (and more expensive) packaging for a simple resistor, usualy arround 320 Ohm. If you bridge the correct wires with the resistor, ECU will assume that O2 sensor is alive and kicking, but not ready to provide data and will keep running the open loop without error. At least this is how it worked on Honda Varadero 2009 and probably all other Hondas at the time. NC and newer models may be different, but I doubt it.
    Thank you for the detailed answer, very helpful.

  10. #80
    Senior Member rippin209's Avatar
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    More and more it sounds (to me at least) like the air temp sensor.
    Good news, the part is around $30
    The bad news, you've gone through a lot for it to be something that simple or it would be an internal part like the cracked ring theory

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