Bike Fault W/out Engine Light Or Codes

Discussion in 'Technical Help' started by Lautrec, Mar 18, 2024.

  1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.
  1. Lautrec

    Lautrec New Member

    Mar 1, 2023
    2
    3
    UK
    #1 Lautrec, Mar 18, 2024
    Last edited: Mar 18, 2024
    Having a lot of trouble with my 2016 Street Twin, had it at multiple garages now with no luck. Hoping to see what you would do in my situation.

    There are a number of issues:
    • Coming to a stop pulling in the clutch the revs will dip very low or cut the engine unless I blip the throttle
    • Starting the bike it revs high then drops very low before catching itself back up to a normal idle
    • Infrequently the revs won't catch and it will just cut out - starting after this is difficult if possible at all
    • Going uphill immediately after starting (~2mins) the engine feels quite laboured
    • Infrequently when giving a lot of throttle the power just isn't there, it flatlines
    • There is a noticeable fuel smell when starting, and a burning smell for the first ~5mins of a journey
    • If I just barely and quickly crack the throttle open I can get the bike to stall
    • (EDIT) I didn't mention because it's so difficult to determine, but it occurred to me to say - it does seem like it's worst when it's very wet with rain (maybe even when it's exceedingly humid).
    The following have been done:
    • No engine lights, no fault codes, no odd readings noted
    • Sparks were given the all clear on multiple occasions
    • Vacuums checked - no leaks
    • Connectors checked
    • Multiple services with nothing amiss reported, unable to find any problems but agreed it isn't right
    They have suggested to try replace two sensors, the MAP sensor and intake air sensor. I am going to do that to try but, would you just get a new bike at this point? I fear it's just an unfixable lemon and I have no local access to a Triumph dealer to get any deeper diagnostics. I really don't know what else to do. I love this bike but I rely on it as my primary mode of transport and it just isn't reliable enough to rely on.
     
  2. TRIPLE X

    TRIPLE X Senior Member

    Sep 1, 2021
    255
    113
    Downham Market, Norfolk
    When did these problems start? Is the rubber pipe connected to the MAP sensor?
     
    • Like Like x 1
  3. Lautrec

    Lautrec New Member

    Mar 1, 2023
    2
    3
    UK
    Basically since I've owned the bike, couple years or more.

    Hoses are all connected and undamaged.
     
  4. Eldon

    Eldon Elite Member

    Nov 14, 2018
    4,279
    800
    North Yorkshire
    Where in the uk are you?
    Someone local may be able to assist.

    One of your symptoms points to weak mixture, have you taken a plug out?
    If not yet, do and post a photo?

    I'd check around the headstock wiring as I have a 2018ST and the left headlight bracket has a smoothish edge that does damage to the loom. I've taken mine off, large radiused the corner, re-powdercoated it and refitted. The front brake hose is only just long enough, another 10mm would've been my design, so check that isn't ragging your loom about too on full right lock?
     
  5. Lautrec

    Lautrec New Member

    Mar 1, 2023
    2
    3
    UK
    #5 Lautrec, Mar 18, 2024
    Last edited: Mar 18, 2024
    Non-Mainland so may be unlikely!

    Plugs have been checked by multiple mechanics who haven't reported anything, but I haven't looked myself. I've just bought the tools to do it so I can this week - do I need a crush washer or anything or can I just take them out and re-seat them after?

    Interestingly, my wiring loom has some electrical tape on it that's a bit ragged...I never really thought much of it! Could that be a cause?

    EDIT: I was thinking there but forgot to mention - I have noticed that when the bike is wet that seems to (but doesn't always, it's very hard to diagnose this) be when it's most likely to be at its absolute worst. If the wiring loom is raggedy that may explain a lot.
     
  6. TRIPLE X

    TRIPLE X Senior Member

    Sep 1, 2021
    255
    113
    Downham Market, Norfolk
    Is there any evidence that the throttle position sensor (located on the end of the throttle body) has been tampered with? Usually set by the factory and marked with yellow paint.
     
  7. Lautrec

    Lautrec New Member

    Mar 1, 2023
    2
    3
    UK
    Is it easy to get at? I'll have a look tomorrow!
     
  8. TRIPLE X

    TRIPLE X Senior Member

    Sep 1, 2021
    255
    113
    Downham Market, Norfolk
    I am a Speed Triple owner so not that familiar with the Street Twin. I assume it is located under a cover on the end of the throttle body. Perhaps Eldon can help out?
     
  9. learningtofly

    learningtofly He’s not the Messiah, he’s a very naughty boy!
    Subscriber

    Sep 25, 2018
    1,986
    1,000
    Hertfordshire
    Could it be a kinked fuel line?
     
  10. Lautrec

    Lautrec New Member

    Mar 1, 2023
    2
    3
    UK
    Checked the plugs, they look fine to me.

    Don't know where the TPS is so not sure where to look. Didn't see anything obvious and my manual just says not to touch it so doesn't point it out.

    The wiring loom on the headstock looks pretty ragged, I've electrical taped it better for now. Didn't see any fraying or exposed wires. Checked behind the headlight too, nothing stood out to me.

    Not sure what that leaves really. I guess on balance it's an electrical issue that's really difficult to diagnose without error codes. A sensor or wire is reading wrong but that's not being picked up by the ECU. It all seems to be in the low rev range, clutching in from lower revs to a stop, cracking the throttle a tiny amount - the revs just drop dramatically.
     
  11. Linx

    Linx Well-Known Member

    Mar 14, 2020
    197
    93
    Stratford Upon Avon, UK
    The TPS will be on the side of the throttle body with an electrical connection to it. I'd replaced the MAP and the MAFF sensors.
     
  12. Bolosun

    Bolosun Well-Known Member

    Aug 25, 2020
    222
    93
    Crewe/Cheshire
    Still reads that something is wrong with the vacuum tubes. I would recheck and make sure they are routed/connected correctly.
     
  13. Samsgrandad

    Samsgrandad Senior Member

    Dec 15, 2019
    504
    243
    Somerset
    Wasn't there a recall for the wiring around the headstock on early Street Twins??
    My memory may be playing tricks but it would be worth checking the DVLA website to see if there was a recall.
     
    • Like Like x 1
Loading...

Share This Page