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Thread: Rough Idle, Poor Fuel Economy, Engine Cutting Out Under Hard Throttle

  1. #1

    Question Rough Idle, Poor Fuel Economy, Engine Cutting Out Under Hard Throttle

    2006 R12RT with 105k miles. Freshly Serviced with Valves and TB Sync as well as 4 Plug Change. Ongoing and worsening problem, so not due to recent SVC action. Fuel Economy has dropped 10MPG, bike idles roughly or quits after 30 second enriching ceases. Hard throttle/passing action makes it stumble and halt, rolling throttle off to a particular point and she returns to full power. Roll it back on and she goes away...this is consistently repeatable. Also quite scary. No spitting and popping. Research leads me to believe it is either a vacuum leak or Throttle Bodies worn slap out. Any thoughts or experiences appreciated...

  2. #2
    Quote Originally Posted by thatmanstu View Post
    2006 R12RT with 105k miles. Freshly Serviced with Valves and TB Sync as well as 4 Plug Change. Ongoing and worsening problem, so not due to recent SVC action. Fuel Economy has dropped 10MPG, bike idles roughly or quits after 30 second enriching ceases. Hard throttle/passing action makes it stumble and halt, rolling throttle off to a particular point and she returns to full power. Roll it back on and she goes away...this is consistently repeatable. Also quite scary. No spitting and popping. Research leads me to believe it is either a vacuum leak or Throttle Bodies worn slap out. Any thoughts or experiences appreciated...
    So it seems to be going lean. My first thought is partially clogged injector(s). A good dose of Chevron Techron injector cleaner in a tank of gas would be my first step.

    Otherwise get it on a GS911 or dealers computer and see if there are any codes regarding a temperature or other sensor.
    Paul Glaves - "Big Bend", Texas U.S.A
    "The greatest challenge to any thinker is stating the problem in a way that will allow a solution." - Bertrand Russell
    http://web.bigbend.net/~glaves/

  3. #3
    Lost again Texpaul's Avatar
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    I had similar issues on my '05 GS. Turned out two of the coil caps were bad.
    Paul Mulhern
    MOA# 56330
    The biggest mistake people make... is thinking they have time.

  4. #4
    I had a similar although not as severe issue on my 05 GS. It turned out be a bad coil on secondary spark plug.

  5. #5
    Will BMW never learn. We went decades with conventional coils and with few exceptions had no problems. Then along came the wretched stick coils and they are nothing but fragile and problematic. Sheesh!
    Paul Glaves - "Big Bend", Texas U.S.A
    "The greatest challenge to any thinker is stating the problem in a way that will allow a solution." - Bertrand Russell
    http://web.bigbend.net/~glaves/

  6. #6
    drgnhtr
    Join Date
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    Location
    Castro Valley Ca.
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    Consistently repeatable

    I've had coil problems too but they were never "consistently repeatable". On both my GS and my RT they were very random.

  7. #7
    Registered User
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    Stick(s) maybe. Vacuum maybe. A sloppy hand in service might also damage lead(s).

    Check codes and see if they indicate anything helpful.

    Unless you're a decent mechanic I'd let a dealership do it.

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