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Thread: 2004 Rockster problem

  1. #1
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    2004 Rockster problem

    My '04 R1150R Rockster is experiencing an issue I have been unable to resolve. After stopping for fuel or a short break upon startup the bike runs badly, won't idle and has little power. After a 1/4 mile or so it takes off and all is good again until the next fuel stop/break. If it was old school carbed I would compare it to vapor lock---but it is new school FI..it has no canister, it has a z tecknic y-pipe and muffler, all o2 sensors are hooked up. Other than this issue the bike runs well, gets fuel mileage in the mid 40's and has no other issues. I bought the bike in Tennesee and flew in and rode it home to Tucson, the po was on his way to Alaska for a new job and is out of touch so past history is unavailable. Ideas anyone??

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    ...I got nothin...

    If it were me, I would start with the cheapest/easiest thing first. Replace the spark plugs. Take apart and clean throttle bodies. Replace the fuel filter (not really easy).
    You say there's no canister - check all the plumbing that would (should) have been closed off or rerouted when removing that.
    Also begs the question why is the canister gone, was there an issue with getting carbon into the fuel, clogging the filter?
    Maybe it is still clogged or is clogged again.
    That used to happen on the 1100 all the time.

  3. #3
    Registered User roger 04 rt's Avatar
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    Quote Originally Posted by AZDUC View Post
    My '04 R1150R Rockster is experiencing an issue I have been unable to resolve. After stopping for fuel or a short break upon startup the bike runs badly, won't idle and has little power. After a 1/4 mile or so it takes off and all is good again until the next fuel stop/break. If it was old school carbed I would compare it to vapor lock---but it is new school FI..it has no canister, it has a z tecknic y-pipe and muffler, all o2 sensors are hooked up. Other than this issue the bike runs well, gets fuel mileage in the mid 40's and has no other issues. I bought the bike in Tennesee and flew in and rode it home to Tucson, the po was on his way to Alaska for a new job and is out of touch so past history is unavailable. Ideas anyone??
    This is a situation where a GS-911 connected and logging for the first quarter mile would probably give you the insight to know what's happening. It sounds like one of two things:

    Probably one of the sensors is not providing the correct information (air temp, oil temp or slightly possible, barometric pressure). For the first quarter mile, the bike runs Open Loop and selects an After-Start and Warm-Up Enrichment sequence. If it gets the wrong sensor information the Motronic will fuel too rich or too lean.

    The other possibility is that your Motronic needs to be reset. Pull fuse 5 for 10 minutes. Reinstall, Key On, no start, twist throttle fully twice, key off. Start and ride. Compare. If this is the problem, it may come back.

  4. #4
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    Thanks, I am in Colorado for the summer and the bike stayed in AZ. I'll try your suggestions when I get back to the heat.....

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    Well,, I have replaced the coils, stick coils-plugs looked great, reset the ecu, and it still does the same thing. After I stop and restart it needs to sit and idle (poorly) for a minute until the idle picks up and then it runs okay. I am sure there is a lean run issue as it does backfire a bit when letting off the throttle. Any ideas what to do next? Sensors? No vacuum leaks found, fuel pump working normally etc. Was hoping to figure it myself without going to the dealer.......

  6. #6
    Left Coast Rider
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    How's the bike run when you start it from cold, like first thing in the morning?

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    Registered User roger 04 rt's Avatar
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    Can you borrow a GS-911?

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    The bike runs fine in the morn when it is cold, starts, idles and takes off normally. There is not much of a BMW community in Tucson, Phoenix is good but don't really know anyone there well enough to borrow a $300 dollar tool......

  9. #9
    Registered User roger 04 rt's Avatar
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    Quote Originally Posted by azduc View Post
    My '04 R1150R Rockster is experiencing an issue I have been unable to resolve. After stopping for fuel or a short break upon startup the bike runs badly, won't idle and has little power. After a 1/4 mile or so it takes off and all is good again until the next fuel stop/break. If it was old school carbed I would compare it to vapor lock---but it is new school FI..it has no canister, it has a z tecknic y-pipe and muffler, all o2 sensors are hooked up. Other than this issue the bike runs well, gets fuel mileage in the mid 40's and has no other issues. I bought the bike in Tennesee and flew in and rode it home to Tucson, the po was on his way to Alaska for a new job and is out of touch so past history is unavailable. Ideas anyone??
    Quote Originally Posted by azduc View Post
    The bike runs fine in the morn when it is cold, starts, idles and takes off normally. There is not much of a BMW community in Tucson, Phoenix is good but don't really know anyone there well enough to borrow a $300 dollar tool......
    Since your bike runs well from a cold start, and runs well otherwise, you're trying to figure out why, after a short stop such as filling, your bike runs poorly for half a minute to a minute after you've restarted it. Is that it?

    I know one thing that happens, even after a short stop. The Motronic adds some extra fuel for a while (or is supposed to) based on Oil temp and Air temp. Possibly one of those sensors has a bad connection or is faulty. This is where a GS-911 would quickly tell what is happening.

    You could try to find someone to read the error codes from your Motronic. That would only take someone with a GS-911 a few minutes.

    Below is a graph I've made of some of the sensors immediately after a cold start. Other than the AFR line, the data came from a GS-911. You'd simply be looking to see what your sensors were reporting.

    Another thing you could try is to remove the fuel pump relay after a fuel stop and a short rest, insert a jumper between its pin 3 and 5. This will immediately turn the fuel pump on. Let it run for a minute to purge the fuel system, then put the relay back in and start.

    I'm sure others will have better ideas.


  10. #10
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    Thanks for the feedback. Looks like a trip to the dealer is in the works.

  11. #11
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    The ecu reset via pulling the fuse worked, all is good now.

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