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Thread: Runs Rough after an 1 hour on the road

  1. #21

    Re: Runs Rough after an 1 hour on the road

    Quote Originally Posted by mrflexicoil View Post
    What does the five way tee acutually do?
    Get clogged up (sorry I couldn't help myself)

  2. #22
    Natural Rider Enhancement Blrfl's Avatar
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    Re: Runs Rough after an 1 hour on the road

    Quote Originally Posted by Igofar View Post
    Get clogged up (sorry I couldn't help myself)
    I was going to say it was put there to keep you occupied, but I like your answer better.

    But since someone asked...

    Fuel injection works by calculating out how much fuel to squirt into the air so the air-to-fuel ratio in the neighborhood of 14.7:1.* The amount of air that will end up in the combustion chamber during the intake stroke varies with temperature and pressure, so the ECM needs to know those things to get the right answer. (This is why carburetors have to be re-jetted for altitude and changes in the intake and exhaust. FI can compensate for it in real time.)

    The five-way tee is used to bring a sample of the pressure in all four of the intake manifolds to the manifold absolute pressure, or MAP, sensor, for measurement. The FI system in the ST may use an average, or Honda may have characterized the whole thing well enough to know when to take a reading for each cylinder. In either case, if the plumbing is partially- or fully-clogged, the the amount of pressure the sensor sees will be different than what it actually is. The ECM, having no way of knowing whether the pressure it's seeing is right or wrong, makes a decision based on what it's given and won't fuel the engine the best way possible. If the clog gets bad enough, the ECM might start seeing measurements that are impossible for the range of altitudes where the bike is designed to operate and will register a fault in the system.

    --Mark


    * 14.7:1 is a compromise that nets you the most power for the least fuel consumption. You can make a bit more power by running rich (12.6:1) and consuming more fuel or you can save fuel by running lean (15.4:1).
    Wizzzzzzzzzzzz What's a Blrfl? ... Shameless plugs: STWiki

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  4. #23
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    mrflexicoil's Avatar
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    Re: Runs Rough after an 1 hour on the road

    I did that the other day when it was acting up and did not make any differecne. I listen for the rush of air as you suggested but did not hear anything like that and the bike still run rough.

  5. #24
    playinatwork playinatwork's Avatar
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    Re: Runs Rough after an 1 hour on the road

    I hate to go against Larry and the experts on this board but if it were me, I'd buy a cheap ebay fuel pump and replace the existing one. If it fixes the problem, you can buy a better pump if you like. You are only out $25.00 and 20 minutes if it doesn't work. Sure sounds like a fuel pump to me. I hate swapping parts in hopes of fixing a problem but sometimes it is just easier; especially if there is a known issue.
    Tim
    IBA#48096
    STOC#8729

  6. #25

    Re: Runs Rough after an 1 hour on the road

    You may be treating the symptoms and not the cause.

  7. #26
    peterswa's Avatar
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    Re: Runs Rough after an 1 hour on the road

    The failure code 2 and high fuel consumption speak to the quality of the MAP signal reaching the ECM module. Also because of the problem comes and goes with heat, I would suspect a wire harness compressed by wire tie or pinched against a surface that gets over warm. The insulation around any wire can be reduced with heat and compression and allow a resistive connection between two adjacent wires in a harness at the point of compression. Inspect the harness between the MAP sensor and the ECM for any point of compression or overly tight wire tie, reseat the connectors a the MAP sensor and ECM module. Expect Harness to be hose enough that it can be easily moved a little bit.
    Bill
    Last edited by peterswa; 10-11-2017 at 10:46 AM.

  8. #27

    Re: Runs Rough after an 1 hour on the road

    ....and high fuel consumption speak to the quality of the MAP signal.....which is why I believe it could be the vacuum lines are partially obstructed....and the fact that it comes and goes with heat, could also indicate that the crap that sticks in the lines could be softened up and return to a semi liquid state and move in the lines and through the system. While I have never seen compression causing a resistive connection between two adjacent wires before, does not mean that it may not be the cause, but after seeing so many of them with that code, and finding clogged up lines, that would be my first approach.

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