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Thread: Oilhead surging

  1. #31
    Nickname: Droid
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    Ok, here is how my 94 RS is set up:
    Been using a K&N air filter since I had the bike at 3,000 miles on it. I ran the stock exhaust and fuel system, with Autolite 3923 plugs for years. No issues. Now, my bike is a late 93 build which had NO CAT-Code plug at all. Those early Oilheads ran just a bit more rich. Plug wires, coils, fuel pump, injectors, fuel regulator are all stock, original and untouched. I replaced the fuel filter, finally, at 120k and it looked pretty good when I took it apart.

    Then in about 04 the muffler outlet tube cracked (common to some early Oilheads). I had it TIG welded, but noted more "popping" on decel when it was cracked. Then I got another cracked muffler for nothing and my curiosity led me to cut the can open, study it, make my own internals and TIG weld it up. Looks stock, but deeper tone and breathed a bit easier enough to cause more decel popping (it is not backfiring as many incorrectly claim it). To counter that I added a Techlusion. Balanced the TBs myself and got good results of 45 mpg average and clean plugs.

    Three years back I rebuilt the TBs myself using the Bing kit. The ticking sound on the TB caused by shaft wear made it harder to balance. After I rebuilt both TBs and installed new throttle cables, I again balanced the TBs using my basic old mercury sticks. Nice and smooth again. Bike is still on the original untouched fuel injectors. Though, again out of curiosity, I am taking the injectors to a local diesel injector repair shop to have them flow tested (curious about the current state flow matching), then cleaned and flow matched again.

    But aside from all this, I never had a surging issue. I certainly read up on it when I first got the bike in Oct 94, but can't say I ever experienced it at all, or enough to cause any concern.

  2. #32
    Curmudgeon nrpetersen's Avatar
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    Quote Originally Posted by ANDYVH View Post
    Ok, here is how my 94 RS is set up:.......

    .....But aside from all this, I never had a surging issue. I certainly read up on it when I first got the bike in Oct 94, but can't say I ever experienced it at all, or enough to cause any concern.
    THX! I'm more concerned about ways to make the R bikes perform as they did when new and as configured when new.

    You have answered the problem with a Techlusion. It would be interesting to swap the fuel injectors (L-R) but I don't expect you to do that.......................

    NRP
    Retired w 2005 K1200LT, 2000 R1100RT, & 1975 R90/6

  3. #33
    Registered User roger 04 rt's Avatar
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    Quote Originally Posted by nrpetersen View Post
    Roger - I only started to wade thru the 10+ pages of plots etc in yr earlier posts but couldn't yet see where you can identify which cylinder is missing - (or if they both are). Can you direct me?
    THX
    Niel
    I've only posted about 10% of the data I collected over the past year and a half. I've laid out my case with detail and supporting documents. Since this is the first time that ordinary riders can both program lamda and record the results of combustion, there is still more insight to be gained. I'll continue to post what I find and try to explain it.

    You obviously have a theory, you are skeptically-minded (me too, nothing wrong with that) so you should really try to plan experiments, log data and present it and see where it takes you. With regard to your earlier questions, my post here: http://www.bmwmoa.org/forum/showthre...l=1#post866626, is about the best I can do to explain what I've seen. Since a wideband sensor is one of the most accurate measurements of combustion, I'd be happy to help you set one up on an 1100. You could be one of the first to have definitive data on how the MA2.2 behaves with no Coding Plug installed. There are lots of theories but few measurements.

    RB
    Last edited by Roger 04 RT; 03-20-2013 at 01:45 AM.

  4. #34
    Registered User roger 04 rt's Avatar
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    Quote Originally Posted by ANDYVH View Post
    ...

    To counter that I added a Techlusion.

    ...
    A Techlusion is one way to richen the mixture. On many bikes you have to give up closed loop operation when you install it and I find it hard to tell how much fuel you're adding. But it can work.

    Some of the early 1100 that had a catalytic converter and O2 sensor coded the Motronic by hard wiring in the harness.

    Do you run an O2 sensor?

  5. #35
    Nickname: Droid
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    Not any more. My RS did its part for "green" running for over 15 years. When I installed the Techlusion I disconnected the O2 sensor.

  6. #36
    Registered User roger 04 rt's Avatar
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    Quote Originally Posted by ANDYVH View Post
    Not any more. My RS did its part for "green" running for over 15 years. When I installed the Techlusion I disconnected the O2 sensor.
    There have to be a lot of 20 year-old cats and oxygen sensors that have given up the ghost.

    Just curious, do you have a socket for a Coding Plug with none in it or not even a socket? I remember reading that some bikes had the Motronic coding done in the harness but can't find that in my BMW electrical schematics disk.

  7. #37
    Curmudgeon nrpetersen's Avatar
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    I don't know how one goes about detecting a misfire with instrumentation - especially which cylinder, short of having pressure transducers in each spark plug port. Maybe with the new lo cost solid state ones? It would be a very revealing piece of data. At least we only have two cylinders....

    Also - I wonder how the air mass flow rate is calculated by the Motronics. I presume an algorithm based on throttle position pot & rpm (and eventually air temp and altitude etc) since there is no manifold pressure transducer. Is there precedence for this type of abbreviated engine control?

    At this point I think it is easiest to look at the flow characteristics of actual throttle bodies (including dirty ones), where there is a very very big valve (the throttle) flowing in parallel with a very small manually adjustable one (the BBSs). That's why I keep suspecting the equality assumptions.

    But I agree that anything that could identify a misfire would be a big help.
    Retired w 2005 K1200LT, 2000 R1100RT, & 1975 R90/6

  8. #38
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    No CAT-code plug, and no socket or wiring for it even if I wanted to install one.

    When the Oilhead first came out, Bob Lentini published an article about tuning tweaks on the new engine to boost the midrange torque for the US market. One of the tweaks was to install the Pink versus the Yellow (I think) CAT-code plug. Doing that richened up the fuel to air mix slightly. So I rushed to the dealer to buy the $17 plug. Only to find out when I got home with it, I had no plug at all and no where to put it. So it is resting for 19 years in my parts stash.

  9. #39
    aapasquale
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    +1 on the Booster Plug--just installed one this morning and I have to say that I would not have recognized my bike. No more surge, much more power, smoother idle. a great machine before, wonderful now(1994R1100RS with catalytic converter)
    Tony

  10. #40
    Registered User roger 04 rt's Avatar
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    Quote Originally Posted by nrpetersen View Post
    I don't know how one goes about detecting a misfire with instrumentation - especially which cylinder, short of having pressure transducers in each spark plug port. Maybe with the new lo cost solid state ones? It would be a very revealing piece of data. At least we only have two cylinders....
    If you install a Wideband O2 sensor and run it in instantaneous mode you might be able to record misfire. Is show up as a lean spike like in the chart below. I have not detected this in any of my plots, even when I leaned closed loop lambda to 1.06 (AFR 15.3:1). The bike will stumble at times with that AFR but not misfire.

    Also - I wonder how the air mass flow rate is calculated by the Motronics. I presume an algorithm based on throttle position pot & rpm (and eventually air temp and altitude etc) since there is no manifold pressure transducer. Is there precedence for this type of abbreviated engine control?
    Below is a draft block diagram I'm working on for the MA2.2. The yellow highlighted boxes need further investigation but the overall picture is, I believe, a pretty good representation.

    As an alpha/n type ECU, it starts in a VE table with an air mass estimate based on TPS/rpm, with interpolation for TPS/rpm conditions that are between cells. Next it corrects for air temperature and pressure. Then it measure battery voltage to correct the fuel pulse which does vary with voltage. From my measurements this gets it in the ballparkÔÇöa few percent on AFR. Finally, there will be some type of adaptation value correction.

    The closed loop program is very accurate and does the fine tuning. When in closed loop it can also compare the table driven result with the closed loop result to create an adaptation value that I mentioned above. I have not measured the R1100 so I can't say how extensive these adaptation values are. But some information on Anton's site describes their existence.

    RB




  11. #41
    Registered User roger 04 rt's Avatar
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    Quote Originally Posted by ANDYVH View Post
    No CAT-code plug, and no socket or wiring for it even if I wanted to install one.

    When the Oilhead first came out, Bob Lentini published an article about tuning tweaks on the new engine to boost the midrange torque for the US market. One of the tweaks was to install the Pink versus the Yellow (I think) CAT-code plug. Doing that richened up the fuel to air mix slightly. So I rushed to the dealer to buy the $17 plug. Only to find out when I got home with it, I had no plug at all and no where to put it. So it is resting for 19 years in my parts stash.
    That must have been a pain at the time. I have read other places about the units shipped with cats not having sockets for the plugs. In that case I believe that the three pins on the Motronic are hard coded in the wiring harness.

    I've read a lot of what Rob wrote, and have been through the coding plug intake tubes stuff a couple times. The one thing I'll say is that Rob's work was hamstrung by the lack of datalogging tools. I've tested different plugs and logged the AFRs on my 1150. I couldn't find anything that would fuel any richer than the pink plug. Even if I could, closed loop adaptation would negate the changes. An active oxygen sensor makes these Motronics very stubborn and brings them back to 14.7. On the 1100s the situation is different. I believe that the beige plug and no plug run an open loop fueling pattern.

  12. #42
    Registered User roger 04 rt's Avatar
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    Quote Originally Posted by aapasquale View Post
    +1 on the Booster Plug--just installed one this morning and I have to say that I would not have recognized my bike. No more surge, much more power, smoother idle. a great machine before, wonderful now(1994R1100RS with catalytic converter)
    Tony
    Glad the test worked out. It's been my experience through measurement that the effects of the BoosterPlug get adapted away over time by the Motronic. I can't say for sure that every model does because I only have data from 1150s and 1200s. The effect can be made permanent in a couple different ways: pull the O2 and go Open Loop or shift lambda by, for example, adding a Wideband O2.

  13. #43
    Registered User flat_twin's Avatar
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    My 99RT was a terrible surger even after tedious careful tuneups. 1st generation Techlusoin in open loop, O2 sensor disconnected made a huge difference. I sold it to a friend and let the Techlusion go with the bike.
    2001 RS, a mild surger but not bad. I knew the Techlusion would make it go away completely so that's what I did. By then it they had a version with factory plugs so no wire splicing to install. Like the first one I ran it in open loop mode with the O2 sensor disconnected. It's been trouble free for 10 years. It also has GS tubes (can you say honk!) and 90 fewer pounds than the RT. Runs strong, runs smooth, I love it! TB's still good, no ticking or sync issues. Best BMW I've ever had.

  14. #44
    Registered User roger 04 rt's Avatar
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    Here is a surging candidate that wjg04oh found the other day. While riding with an AFR gauge he noticed that his motorcycle (which has an LC-1 installed), was running Open Loop and leaner than Closed Loop above 3500 RPM in first, second and third gear. After he posted it I tried the same thing and got the same results.

    Because we are both running our Closed Loop 6% richer than stock, the AFR we recorded was in the vicinity of 14.4/6:1. If we had been running with a stock O2 sensor that would have been a very lean 15.3:1 and with some cylinder fueling/air mismatch, which is inevitable, it might reach 16:1.

    Because Wally noticed this, I think we now have a very clear data point showing that stock bikes at 4000 RPM and above, at small throttle angles (1st, 2nd, 3rd gears, level terrain), exhibit very lean fueling, and could easily be prone to stumbling or surging in those conditions.

    To me, this is an exciting finding, certainly not anything I expected. Here is a graph showing the leaner than Closed Loop fueling on my R1150RT.


  15. #45
    Jammess jammess's Avatar
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    Sent injectors from my '04RT to RC engineering for cleaning today. I want to really find out just how good my 1150 will run after I installed the LC-1. Wasn't going to bother with injector cleaning and balance check but I think this should be done especially if you use an LC-1 wideband sensor.
    Jammess

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