Sprint Running Rough Under 2500rpm

Discussion in 'Technical Help' started by Hughsie, May 20, 2019.

  1. Hughsie

    Hughsie Member

    Apr 21, 2017
    31
    18
    Dublin
    Howdy folks - my 2010 Sprint ST has been running really rough lately.
    And it only seems to happen when I'm under 2500rpm - which is a pain, because I city commute so i spend a fair bit of my time in that range!

    I've reloaded the original map and reset the TPS - that seemed to work - then 2 days later, back to rough again.

    Any ideas out there?
     
  2. freck

    freck Elite Member

    May 4, 2017
    1,718
    750
    Preston, Lancs, UK
    What’s the mileage, when was it last serviced?
     
  3. Ken walburn

    Ken walburn Noble Member

    Jun 28, 2017
    889
    300
    Essex
    The fact that you reset the TPS & after a couple of days the issue returned. A reading of fault codes pending would be useful. I would be checking the voltage readings from your TPS from idle through to WOT. Could be all kinds of things causing the issue, but you’ve gotta start somewhere. If TPS readings ok, I noticed you mentioned reloading the orig map ( reset the ECM) this would take everything back to factory settings. It would take at least 20 miles of riding for the ECM to adapt to the information it receives. If one of these readings steps outside parameters, it will attempt to compensate. Check basics before getting too involved. Compression / spark (plugs - coils) / fuel delivery
     
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  4. Hughsie

    Hughsie Member

    Apr 21, 2017
    31
    18
    Dublin
    About 27,000 miles Freck.
    Last serviced in October - pads, filters, fluids etc
     
  5. Hughsie

    Hughsie Member

    Apr 21, 2017
    31
    18
    Dublin
    No fault codes when plugged into Tune ECU Ken
     
  6. Ken walburn

    Ken walburn Noble Member

    Jun 28, 2017
    889
    300
    Essex
    You do not always get a fault code with a TPS, because of the wide range between closed throttle & wide open throttle, likewise with the ECT (engine coolant temp sensor) from cold to hot. Check both of the readings of these throughout their ranges before going down the plugs route. A faulty spark plug could play up under engine load & perform better further up the Rev range. Oh what to do ?!? :worried:
     
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  7. Hughsie

    Hughsie Member

    Apr 21, 2017
    31
    18
    Dublin
    Jesus! Could it be as simple as a spark plug?!!!!
     
  8. Ken walburn

    Ken walburn Noble Member

    Jun 28, 2017
    889
    300
    Essex
    Could be. Or a small air leak causing the mixture to be too weak (just another option for you to mull over o_O)
     
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