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Thread: Fuel delivery system and surging/buckling

  1. #1
    Registered User amtoro's Avatar
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    Fuel delivery system and surging/bucking

    For months, I had been experiencing one of the most annoying surging conditions on my '04 R1150RT; with the help of some of our chartered club members, we did a conscious valve adjustment, changed the fuel filter and TBS with little to no improvement.

    A constant misfiring was also occurring, and after troubleshooting with a new ignition coil (which ended up replacing the oldest one still on the bike as one had already been replaced by the previous owner), the misfiring went away after another TBS.

    So, fuel delivery seemed to be ok, air delivery was also fine, and the spark was strong with new spark plugs installed at the time of the valve adjustment. However, there was a noticeable lag when applying quick throttle, and a hesitation and buckling while accelerating; only under very light throttle, I could increase speed in a more-or-less linear way.

    At this point, with a warm engine and after coming to a stop, the bike would slow down to a nice tickle and idle fine at about 1,100rpm for about 30 seconds and then just stall... it would start fine, and then stall again without warning. I was also experiencing difficulty warming up the bike in the mornings unless I was manually opening and closing the throttle.

    Two weekends ago at Rider's hill in Dahlonega, GA, at the final stop of a day ride with the local group, and after discussing my maladies with other two 1150RT owners, one of them directed me to another rider who, according to him, knows RT's better than most.

    After describing the condition to him, he replied that the best thing I could do was to have the injectors professionally cleaned. He said he didn't have to hear the bike, but then asked me what mileage it had; 42k, I replied... he ratified his diagnosis, we shook hands and I left.

    I didn't mention this to him, but I had tried a few bottles of injector cleaners and they tried to improve the condition with minimal effect, so I thought he could, very well, be on the right track.

    Fast forward to yesterday. I received my injectors back from ProFlow and installed them after looking at their report where stated that their spray pattern was good before the cleaning, but that the flow rate was apart from each other and a bit low; the report indicated an improvement in the flow rate of 5.6% for one of them and 8.3% for the other. Not much in my opinion and the voice in my head was saying that I had just thrown my money away.

    Start... perfect idle... test ride... it is like I'm riding a horse out of hell. The bike delivers its power completely lineal from bottom to top, all the way to the top! this is the bike I fell in love with and it is back.

    My suggestion is: Consider the possibility of a lightly clogged injector if the power delivery does not feel right and if there is something irregular at idle (when little fuel in being injected, the lack of enough flow will magnify the problem). I think I will send my injector for cleaning every 36k-42k miles and run a bottle of teckron for maintenance every 10-15 fill-ups.
    Last edited by amtoro; 04-23-2013 at 06:45 PM.
    '04 R1150 RT

  2. #2
    Unregistered user norton's Avatar
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    Good news on the injectors! Can you provide more details on where you sent the injectors as there are a lot of companies named ProFlow.

  3. #3
    Registered User amtoro's Avatar
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    I sent them to ProFow Technologies in New Port Richey, Florida. Their website is www.proflowtech.com
    '04 R1150 RT

  4. #4
    Happily Bent dieselyoda's Avatar
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    In our shop where we do almost entirely diesel stuff, we also do gasoline injectors. The usual procedure for us is to start with removing the filters inside the injectors. You can barely see them and a special tool is required but they are there. During the cleaning, a special solution is flowed through the injectors under an ultra-sonic wave for about two hours, our shop anyways. We rarely pre-test injectors as they almost always fail before the filter change and cleaning. After the cleaning, they go through an electronic test cycle that includes almost any condition an ECM can control for that given series of injector. Full flow and chattering flows are measured but the actual percentage difference between injectors can be very broad, as per OEM specs.

    After that, the heat shield is replaced and the o-rings. Usually, the manifold or TB o-ring is an OE only but the fuel rail o-ring is pretty standard. I hope that makes you feel better about spending some coins.
    1997 R1100RT (Restored Basket Case) , 1981 KZ 440 LTD (Restored Basket Case)
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  5. #5
    Registered User roger 04 rt's Avatar
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    Cleaning and measuring fuel injector balance is one of the most important, but most neglected parts of getting a lean-burn (14.7:1) engine to run smoothly. I've seen several reports this spring of riders who, after having their injectors cleaned, have reported much better running and less surging.

    Those who I'm working with who've used LC-1s to richen their mixtures, which lessens the requirement for injector balancing also have benefitted by injector cleaning. Pre-cleaning they've reported smooth, strong low-end power. Post-cleaning, and I've experienced this too, they've reported noticeably reduced vibration in cruise.

  6. #6
    Registered User amtoro's Avatar
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    Stalling at IDLE ended up being lack of power to coil sticks

    Well.... the problem came back....

    This time, I cleaned the combustion chamber with a can of the Berryman's combustion chamber cleaner that comes with a hose and gets delivered through the vacuum lines. (I assembled a "t" connection and two more vinyl tubes to deliver it to both cylinders at the same time.

    A lot of carbon came out of the back after the process but the stalling was still there.

    I found a YouTube video for checking the spark on the Stick coils (of which, one was replaced by the previous owner about two years ago, and the other by me when this problem first started.

    I discovered that none of them gave sparks, so I left them unplugged and removed one secondary plug at a time; the engine stopped almost right away and would not start with the secondaries unplugged and only the main plugs securely connected.

    My suspicion then turned to lack of 12V current to the primary plugs and that the bike had been running on secondary plugs this entire time

    After finally finding the wiring diagram for the dual spark '04 R1150RT, which is quite difficult to find, I came across the remark that some bikes of this model and year have a Load Relief Relay for the main plugs and the wire is of a different color.

    Part of the reasoning was that in the bikes without the relay, the same 12V line feeds both sets of plugs, therefore, if that wire had been damaged, I should not have a spark on the secondary plugs either; instead, I have one 12V line to my main plugs and one line to the secondary plugs.

    Here is the process of elimination that I followed based on the wiring diagram by Dough Raymond available here: R1150RT-2-Plug-Elec-Diagram-V1_1.pdf

    Unplug the wire connectors to the stick coils and note their colors:

    Left cylinder.
    Brown (ground from the HV coil)
    Green with black line (12V)
    Black with violet line (Motronic)

    Right Cylinder.
    Brown (ground from the HV coil)
    Green with black line (12V)
    Black with green line (Motronic)

    The 12V wire is solid green in bikes without a load relief relay and green with black in those that have it. (Nobody seems to know why only some bikes have this)

    With the ignition off, I checked conductivity on the green/black wire from one cylinder to the other and ground connectivity from each of the brown wires; all ok

    With the ignition ON, I looked for 12V at the Green/Black wire and found none. That is why there was no spark on the primary plugs.

    I opened the fuse box and found a yellow relay in the position 11 (See picture below) that is not present in other dual spark RT's of the same year.

    The relay was loose... it took some work to hold the relay holder from below to correctly and fully engage the relay but after that I was able to read 12V at the connectors to the coil sticks, the bike runs as it should.

    I also checked the coil sticks for conductivity and they are true and correct.

    As the engine speed now climbed at IDLE to almost 1600 rpm, I adjusted it and balanced throttle bodies. It's all good now.

    I hope this helps someone one day.

    TwinSparkScaled_zps98e0ec22.gif
    '04 R1150 RT

  7. #7
    Registered User roger 04 rt's Avatar
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    Well done!

    This past winter, I contacted Doug Raymond and asked him to produce the drawing that you reference. Although you can find it if you have the BMW SLP 2.2 disk (which I have) I realized that there was no other document (that I'd ever seen) including the Haynes and Clymer manuals, that showed the detail of the dual spark system.

    Prior to them being available I'd posted this: http://www.bmwmoa.org/forum/showthre...cal-Schematics, see the fifth item.

    I don't have the second relay that provides +12, you're the first I've heard that has that relay.

    After spending about a month of emails with Doug to get all three schematics updated, I'm really glad to hear that they were helpful.

    RB

  8. #8
    Registered User amtoro's Avatar
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    It has been an exciting learning process and I really hope it help others one day; I have learned to check the coils, I have understood the electrical system of this particular model and the possible reasons that BMW had for these minor changes to the R1150RT just months before unveiling the current R1200RT.

    It would be interesting to probe how many owners have the yellow relay and how many do not; this only applies to dual spark models.
    '04 R1150 RT

  9. #9
    MOA #24991 Pauls1150's Avatar
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    I have a yellow relay to the left of the cat plug, but there's another empty relay location to the left of that - so which spot? The picture doesn't show an "empty" detail.

  10. #10
    Registered User amtoro's Avatar
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    This is a picture of the RT's fuse box (I'm pointing at the relay). In bikes without the relay, there is nothing in that area of the box and all you see is a bunch of cables below.

    In the bikes with the relay, there is a double relay holder and the space next to the yellow one is empty.

    image.jpg
    '04 R1150 RT

  11. #11
    MOA #24991 Pauls1150's Avatar
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    Yup, mine's identical.

  12. #12
    Registered User roger 04 rt's Avatar
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    Quote Originally Posted by amtoro View Post
    This is a picture of the RT's fuse box (I'm pointing at the relay). In bikes without the relay, there is nothing in that area of the box and all you see is a bunch of cables below.

    In the bikes with the relay, there is a double relay holder and the space next to the yellow one is empty.
    So is the relay there to take current load off the key, to provide a low resistance connection between the coils and battery or to eliminate stick coil voltage transients from the other circuits? Or something else?

  13. #13
    Registered User amtoro's Avatar
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    I would think that its purpose is to separate the primary plugs from the secondaries and allow a margin of safety for either a lower load on the wire or to allow the bike to continue after the failure of either the primary or secondary circuits.

    It basically creates an independent circuit, directly from the battery to the primary plugs
    '04 R1150 RT

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