Throttle hesitation R1100GS

Discussion in 'GS Boxers' started by NW Cascade Rider, Oct 7, 2012.

  1. NW Cascade Rider

    NW Cascade Rider Dual Sport

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    So I have been working this issue for a while now. I changed the fuel pump, filter, and what I'm going to call the fuel rail/distributor with the fuel pressure regulator. I am quickly running out of ideas. I performed the "zero zero" today as well as removing the "rose" from the fuse box and jumping pins 30 and 87 as well as pulling fuse 5 to reset the motronic. The throttle bodies were synced not to long ago as well.

    The symptom it self is: Under heavy / hard acceleration, or past about 65 MPH the throttle goes flat. No power at all, and if anything I'm loosing speed. However at a low power demand, I.E, riding below 65 at a calm pace, and idling, the bike is just fine. It is a little rough starting when cold, but once warmed up, idles just fine with maybe just a cough every now and then.

    The only mods I have on the bike are a GPR exhaust system with a cat delete and a K&N air filter. Any input or help to resolve the issue would be a huge help. I am very mechanically competent. I could just replace all the parts that I would suspect are causing the problem. But I would prefer some wisdom and input with people who have experience with these bikes.
    #1
  2. NW Cascade Rider

    NW Cascade Rider Dual Sport

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    I forgot to ask, where do you guys get your parts from. I have had issues finding parts for the bike. And are there any maintenance or mod items that I should consider or do? Again any input would be hugely apreciated! :D
    #2
  3. GAS GUY

    GAS GUY MILE EATER

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    Beemer Boneyard has alot of parts with Advrider discount.

    Are you sure your transmission isn't skipping under hard load ? It is a common problem.
    #3
  4. NW Cascade Rider

    NW Cascade Rider Dual Sport

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    I'm not sure how the transmission could skip under a load... Only place I would know a skip to be even possible would be in the clutch it self. But if you care to explain, I'm all ears. But I think its really related to the engine its self.
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  5. GAS GUY

    GAS GUY MILE EATER

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    It has been awhile but basicly the most common Feeling is when getting on it hard the bike feels like it cuts out till you let off the throttle.
    There has been discussion on advrider about it You will have to use google and search as I don't remember all the details.

    Or does your bike stay smooth but just run out of power??
    Could the clutch be slipping ? Do the rpms go up when it happens ?
    Maybe the fuel injectors are not flowing enough ?
    #5
  6. mouthfulloflake

    mouthfulloflake Not afraid

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    It sounds to me as if you have a serious mis match of fuel to air ratio under those load conditions.

    if you remove the rose colored CCP, and pull out your 80 37 jumper, it should operate in its richest ( fuel) possible mode I think.


    if that alone does not fix it, try that in addition to the stock air filter.

    and if these moderate steps toward adding more fuel than air to your mixture under load do not help, well, then you know you have some other issue..

    cat removal, aftermarket exhaust, and different than stock air filter could certainly surpass what the machine is capable of mixing a good fuel.ratio for in my opinion.

    maybe you need a power commander, or some other device to add more fuel.
    #6
  7. slartidbartfast

    slartidbartfast Love those blue pipes

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    Did you check the filters/screens in the fuel injectors. You can apply a 9V battery across the terminals to open the injector and back-flush with carb cleaner to clean out any accumulated sludge.
    #7
  8. vintagerider

    vintagerider Long timer

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    Like m-f-f said, the exhaust mods you made require re-chipping or other measures, still I sense that with such a dramatic loss of power there is something else amiss.

    Check the tank tank vent by blowing with your breath in to the end of the hose. Are you running vapor recovery (charcoal canister)? Any vacuum in the tank? Unplug the Lambda sensor and try no jumpers. Never had to resort to alt jumper with the 1100, Motronic 2.2 is not the same as 1150.

    Since this is a WOT problem could be fuel or TPS.

    Clean the injector screen (any tank liner flaking?).

    Did you clean the ports in pump plate when you changed the pump? usually will have lots of detonation or pinking about 4-5k under load, hard accel if the mixture is too lean especially on CA winter mix fuel.

    FTI if the TPS goes bad then symptoms will be much like a clogged fuel filter with serious loss of power because Motronic has faulted to limp home. Read the fault codes.

    Finally, remove the intake manifolds and check them -very- carefully. Built in o-ring on the head side may be gone. Clamp may have been over-tightened. OZ guys have reported success in "repairing" them with o2 sensor safe high temp RTV.

    If you pull the plugs don't forget to clean the head airways top, front, back thoroughly before de-plugging. Avoid frying Motronic by not cranking the engine unless a new plug is fully grounded.
    #8
  9. NW Cascade Rider

    NW Cascade Rider Dual Sport

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    I looked up that transmission fault you referred to and I don't think that matches my symptoms at all. I red that the problem is in 5th gear under a load. However my issue can be in any gear under heavy load or WOT. I am going to clean the Injectors and throttle bodies today and report what I find.

    The fuel pump was replaced because of the flaking in the fuel tank. The tank liner got into the old fuel pump and clogged it up as well as the fuel filter and caused them both to fail.

    As far as fuel tank venting, I rode the bike a couple weeks ago with the fuel filler cap open and still had the same symptoms. With regards to the aftermarket pipe. The bike was running fine both before and after I installed it. This surging problem is very recent.

    I still suspect that the TPS is most likely bad, but I want to rule out all other options before I go replacing it because its a $150 part. Ill have an update after I clean the fuel injectors and throttle bodies. Thanks for everyone's input!
    #9
  10. mouthfulloflake

    mouthfulloflake Not afraid

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    have you tried to set the tops voltage?

    http://advwisdom.hogranch.com/Wisdom/tps3.1.pdf


    while the meter is attached to the TPS slowly open the throttle, and observe the meter reading, it should register a fairly steady increase over the idle setting (0.360 volts)
    #10
  11. vintagerider

    vintagerider Long timer

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    Given the fact that you have liner failure the new filter can again be plugged. Clean the injector screens.
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  12. NW Cascade Rider

    NW Cascade Rider Dual Sport

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    I reset the TPS voltage yesterday following the procedure in this link:

    http://www.ibmwr.org/r-tech/oilheads/zero528.shtml

    I just got done cleaning both the fuel injector screens and the throttle bodies. I'm about to go re install them on the bike. I am really eager to find if it helps or not....
    #12
  13. NW Cascade Rider

    NW Cascade Rider Dual Sport

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    So after removing, cleaning, re installing, screaming and banging, and a little bit of probing, I think I have found my problem. I have a bad coil pack and or plug wires. The bike has 66K miles on it right now and some how I'm not all that surprised.

    I came to this conclusion because after I got done re installing the cleaned TB's and injectors the bike would hardly start (cold). I then removed the injectors from the TB's to make sure there was fuel flowing, and found that both injectors were working flawlessly.

    I then moved on to inspect any miss connected linkages and security of injector harnesses and fuel fittings and found no fault. The few minutes it did actually run, albeit rough, I found that only the Left jug was heating up and the Right jug was getting warm, but very slowly... I pulled the wire out (not while running) on the right and plugged in a spare spark plug I had and found that the spark was a weak orange red. I re inserted the Right plug wire and cross checked the Left jug and found the same symptom. So that tells me definitively that I have either a bad coil or bad plug wires. Either way I am going to replace both.... Again any thoughts and input is appreciated!
    #13
  14. slartidbartfast

    slartidbartfast Love those blue pipes

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    Note that the 1100 has a wasted spark and a dual output coil. Every time the ignition fires, the spark energy essentially makes a loop, jumping the plug gap in both plugs at once. While a weak coil will definitely make the bike run badly, especially at high throttle openings, it should affect both cylinders equally. If it is only affecting one cylinder then the problem could lie with a short to ground from one coil terminal, one plug lead or inside one plug cap. Replacing the whole lot is probably a smart move anyway.
    #14
  15. NW Cascade Rider

    NW Cascade Rider Dual Sport

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    It was firing on both cylinders, it just seemed to favor the Left jug a bit more. But the spark on both cylinders was very weak. And both TB's showed evidence of back fire / miss fire. Again, missing more in the Right jug than the left. I was not aware that the Ignition fired both cylinders at the same time. that being the case, Is there a good alternative coil or a coil with the same part number that would be a good replacement? If I could find a coil that had the same ohm and voltage output that would be sweet.
    #15
  16. slartidbartfast

    slartidbartfast Love those blue pipes

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    I think there are several companies selling more cost-effective replacements to the expensive BMW ignition coil from a dealer. I just had a look and Euromotoelectrics has it listed here, Beemerboneyard has used replacements listed here (out of stock at the time of posting) and Motorrad Elektrik has them listed here. No special reason why you should go to them as I'm sure you could find other sources also - these were just the first places I looked. These guys also all state that early oilhead coils were failure prone.
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  17. NW Cascade Rider

    NW Cascade Rider Dual Sport

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    Motorrad elektrik has no way to order the part. Every time I click order, It sends me to linksys website... And the other 2 websites are out of stock... so is there any other place I can order the part from?
    #17
  18. vintagerider

    vintagerider Long timer

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    Common to see black soot in TB's. Characteristic of the engine from the lean burn.

    Good explanation on the ignition sl-b-fast

    The 1100 coil, unlike the 1150 dual spark, is pretty robust. Pull the coil and check the resistance cold and heated with heat gun. The published resistance is wrong in many manuals. Check the spark wire resistance. Solid core so they usually don't go bad but the insulation weakens and energy can jump to ground. Can see at night. BBY and EME. EME use to carry the Bosh coil packaged with a plug wires for cheap but now only seems to have the wires:
    http://www.euromotoelectrics.com/Ignition-Wire-Set-BMW-R-Oilhead-BMW-WSR641OE-p/bmw-wsr641oe.htm

    edit: Slardi beat me to it! Wonder why the supply of the new style Bosch has dried up. Maybe the revised Bosh coil was nfg. What is BMW selling? I've been lucky with my old Bosh coils. I f Rick says the "early" ones were weak then he ought to know. Got to be a substitution out there but mounting will be an issue.

    I would still resolve the loose tank liner and pull the intake manifolds when you get a chance.
    #18
  19. slartidbartfast

    slartidbartfast Love those blue pipes

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    On their web site Motorrad state they do not have direct ordering from their website as a phone call allows troubleshooting to help ensure you get the right part. 866-668-6353
    #19
  20. roger 04 rt

    roger 04 rt Long timer

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    I know you have tracked this down and believe that your spark coil may be at the root of the problem. If that doesn't work out, you may want to check another aspect of your fuel delivery--volume and/or pressure.

    This past summer I had symptoms very similar to yours--bike would run at lower speeds but open the throttle and it would die (story). When I checked the injectors, there was fuel. In my case though, within a half hour of experimenting, my bike (1150) refused to run. It would start but if I touched the throttle it would die. To make a long story short, two of the hoses inside the fuel tank had cracks in them that were limiting the volume of fuel that the pump could deliver. The cracks were not obvious.

    Afterwards I realized there were two simple tests. First, check the return volume from the fuel distributor going back to the tank. At idle it should be about 2 liters per minute (less that 1.5 liters and you'll have a top-end fuel delivery shortage). Second, check the fuel system pressure if you can get your hands on a gauge. It should be 43.5 psi plus or minus a few psi. Since the fuel pressure regulator rarely fails, the return-volume test may be faster and just as illuminating.

    Good luck.
    RB

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    #20