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Thread: 1997 R1100RT CO Pot-For information only, not a problem to be discussed for weeks

  1. #16
    Day Dreaming ... happy wanderer's Avatar
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    Not trying to be adversarial at all. Just tossing in some info and opinion on stuff I've learned along the way. Use at will or not.

    Since there is no documentation available on the Motronic ECU's design and no public details on it's logic, not even a simple flowchart, most of what is known about how it works has been through test and observation and stuff gleaned from the factory manuals.

    I think you are correct that a fault can force open loop operation in the Motronic. A great example of this is if you disconnect the O2 sensor to force it to run open loop. It has no signal to run open loop with and it definitely throws a fault code. (See below)

    I'm curious about the hard fault code you had and how you read the code or tested it. Is it possible it was reporting a bad O2 sensor? Easy enough to find out.

    This is pasted from IBMWR BMW maintenance manual in case anyone is interested.

    Motronic Fault Codes - Stefan Hegnauer

    Warning!: Although unlikely, it may be possible to screw up the Motronic. I take
    no responsibility of any kind if you do so - in other words, it is your risk, and you
    are on your own if something fails. If you are not absolutely sure you can handle
    this, do not attempt this procedure!
    Note 1: There is no connection of the Motronic (diagnostic unit) to any lights
    Note 2: This is strictly for R1100R/RS/GS/RT, Motronic 2.2. I have no idea about
    the Motronic 2.4 of the R1100S and R1150 family.
    1. Get an analogue Voltmeter (digital ones are usually not fast enough, so you
    could get wrong readings)
    2. Hook it up between pin 1 of the diagnostic connector and ground (battery -,
    chassis), switch ignition on (if you don't start or just very briefly turn the engine,
    codes 1122 and 1133 will show, which is normal)
    3. With a separate wire, connect the same pin 1 to ground for at least 5 seconds,
    then remove the wire
    4. The needle of the voltmeter should go to nearly zero for about 2.5 seconds,
    then rise again to almost 12V
    5. A series of short dips towards zero follows - count the number of dips
    6. A short pause of 2.5 seconds follows
    7. Steps 5 and 6 are repeated 3 times with perhaps different numbers of dips
    8. You have now four counts, this is the Motronic diagnostic code (see table
    below)
    9. The whole sequence, beginning with the 2.5 seconds dip of 4 above, repeats
    over and over until prompted again (step 3)
    10. The next error code (if any) is shown after prompting

    Example: one dip - pause - one dip - pause - two dips - pause ? two dips - pause
    - long dip - pause (repeat) => code 1122

    Motronic Codes
    0000 no further fault stored
    1111 CO potentiometer
    1122 Hall signal 1
    1133 Hall signal 2
    1215 Throttle butterfly angle sensor
    1223 Engine temperature sensor
    1224 Air temperature sensor
    2341 Oxygen sensor at limit
    2342 Oxygen sensor signal invalid
    2343 mixture setting at limit
    2344 Oxygen sensor shorted to ground
    2345 Oxygen sensor shorted to 12V
    4444 no fault stored
    MJM - BeeCeeBeemers Motorcycle Club Vancouver B.C.
    '81 R80G/S, '82 R100RS, '00 R1100RT

  2. #17
    Registered User dieselyoda's Avatar
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    Indeed, I used the method described to find my fault code. Works very well and I would just add that you need patience while doing it.

    I added one step to the process in that I took the bike for a nice run to get it hot, left it running, parked a fan in front and then proceeded with the method described. I was getting tired of seeing the HES codes and was looking for others. In particular, a TPS code because I set the idle so low. Kept getting the CO Pot code.

    I know for a fact that any system that can fire the "Check Engine" light on an OBDI system will be a hard fault and the ECM will not allow closed loop until the code is cleared or repaired. There isn't a "Check Engine" light on this version of the Moronic.

    All the sensor performance can be read through a breakout box to confirm a fault to the ECM, bad sensor, wiring, etc. What you can't do with the Moronic is confirm it sees the sensor signal or if it sees changes that occur faster than it's refresh rate.

    You must also keep in mind that the oxygen sensor has two circuits: the heater and the sensor. They are independent of each other and can be read individually.

    Since the late 80's, my primary troubleshooting practice has been to check grounds and clean if in doubt, confirm the overall tune-up condition, filters, wiring, etc., the basics. Read and record the fault codes, clear them, run the balls off the machine and go back and scan again. More often than not, a returning code, like a MAP error was not the sensor fault but a cracked hose or something like that.

    I had one situation not long ago where the Technician (I use that term loosely to describe this moron) kept telling me my injectors would not fire in one hole. He knew that because his scan tool told him. After a week of arguing and his customer trying to eat my face, I told him to do a valve set. He told me he didn't need to because his scan tool said it was fine. I finally lost my temper, got into it myself and found one lobe on the camshaft worn down, the injector lobe. He ate almost $6K in injectors that I wouldn't return and in the bill I sent him for troubleshooting him being stupid.

    Stay to the basics, look for the simple stuff and fix the problem you know first.
    1997 R1100RT (Restored Basket Case) , 1981 KZ 440 LTD (Restored Basket Case)
    1986 K75S(the beutch), 1993 K1100RS (blown engine), 1997 Chev Short Box (4x4 with an LT1)
    "You can easily judge the character of a man by how he treats those who can do nothing for him."

  3. #18
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    Side question: Dieselyoda, can you share the details and maybe a pic of your Motronic breakout box?
    2000 R1100RT / 1987 K75C (RIP) / Santa Clarita, CA

  4. #19
    Registered User dieselyoda's Avatar
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    I would love to get a picture, I will try

    Quote Originally Posted by JamesInCA View Post
    Side question: Dieselyoda, can you share the details and maybe a pic of your Motronic breakout box?
    My goofy version, the Goofy Disney version of my breakout box is sitting about 300 miles away with a buddy trying to figure out this entire open loop/closed loop thing as his fuel economy is in the toilet.

    Basically, I got a cooked Moronic from a crashed toy and the wiring harness as well. The injector driver circuit was toast in that ECM and since the whole bike was beyond repair, poor bastard t-boned a car, his fault too. That poor bastard broke his pelvis and a bunch of other nasty bones and the bike went for $100.00 at salvage.

    He's still a good buddy though, dumber than a sack of hammers for his stunt riding.

    All I did was reverse the wiring on the ECM connector to the wiring harness connector. Soldered it up and now I use paper clips in the wiring harness connector . I plug the bastardized ECM connector into the bike harness and the bastardized wiring connector into the bike ECM. Now, with a wiring diagram, I can pin out every circuit. This winter with the blown ECM, an electronics dude I have worked with will see if the facility for a "Check Engine" light is there. He thinks it should be. Winter project........lots of time in the winter to mess with crap like this, about 7 months worth of winter.

    Oh, should add, my bragging about my CO Pot addition making my bike run fabulous, never mind.....................................
    1997 R1100RT (Restored Basket Case) , 1981 KZ 440 LTD (Restored Basket Case)
    1986 K75S(the beutch), 1993 K1100RS (blown engine), 1997 Chev Short Box (4x4 with an LT1)
    "You can easily judge the character of a man by how he treats those who can do nothing for him."

  5. #20
    Day Dreaming ... happy wanderer's Avatar
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    Quote Originally Posted by Dieselyoda View Post
    Indeed, I used the method described to find my fault code. Works very well and I would just add that you need patience while doing it.
    ------------------------------------ cut here-----------------------------------------------------------
    Stay to the basics, look for the simple stuff and fix the problem you know first.

    OK. Let's do that . Stay with the basics.
    What was the fault code you found that you fixed with a CO pot?
    MJM - BeeCeeBeemers Motorcycle Club Vancouver B.C.
    '81 R80G/S, '82 R100RS, '00 R1100RT

  6. #21
    Registered User roger 04 rt's Avatar
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    HW, he says that he has a connected O2 sensor and a Yellow Coding plug. What led him to install the CO Pot:

    Quote Originally Posted by Dieselyoda View Post
    I have read a great deal on some of the BMW forums about the need for a CO Pot. Just make sure we are talking about the same thing, Carbon Monoxide Potentiometer. Some of the forums say it is there for idle and needs to be set with an exhaust gas analyzer. My bike, a US bike, didn't come with one and the codes from the Moronic gave me a CO Pot code.
    I'm going to cause some sensor faults on my bike and see whether Closed Loop is disabled on a fault. I don't think it is (other than the O2 sensor fault he has) but it would be good to know.

    You have the same configuration (Yellow Plug and O2 Sensor Connected) do you get the CO Pot Fault Code?
    RB

  7. #22
    Registered User dieselyoda's Avatar
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    Quote Originally Posted by Roger 04 RT View Post
    (other than the O2 sensor fault he has)
    RB
    I don't have any O2 sensor faults. I got code 1111 every time I checked. It was the last fault code in the string. RealOEM and all the other parts fiche show it should be there for my serial number.

    Whether or not that fault prevents closed loop from occurring, I don't know as you can't see closed loop in real time. If you are in closed loop MOST of the time, data logging will see it as ALL the time.

    I know for certain that on CAN systems, you can see periods of open loop through a fast scan tool. I also know for certain that any other fault code besides the one for the CO Pot will keep the Moronic in open loop.

    As of last tank, just under 230 miles of range highway/city as compared to my usual 200. There are too many variables to say the CO Pot was the difference.
    1997 R1100RT (Restored Basket Case) , 1981 KZ 440 LTD (Restored Basket Case)
    1986 K75S(the beutch), 1993 K1100RS (blown engine), 1997 Chev Short Box (4x4 with an LT1)
    "You can easily judge the character of a man by how he treats those who can do nothing for him."

  8. #23
    Registered User dieselyoda's Avatar
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    Some new information about closed loop.

    I know some of the stuff I am about to add is a fact for a lot of ECM's. My buddy pointed out that Bosch made the GMII ECM from about '86 to just shy of '94. I remember those, what a POS, it took less than 2/10ths of voltage drop to make them crazy.

    Here we go: "signal from the lambda sensor is only considered when the throttle is held constant and the engine is not accelerating".

    "closed loop is only in operation up to throttle openings of about 13 degrees".

    "Closed Loop systems usually operate at low throttle openings (below 20%) and below 50 to 60% of max RPM. Above those throttle and RPM points the system goes back to Open Loop operation, running off the fuel maps stored in the ECU."

    "Closed Loop system is only activated once the engine is up to a predetermined temperature....80 degrees C......95 degrees C......the thermostat opening temperature."

    All this information is available from Bosch's book, Gasoline Engine Management. Regardless the O2 Sensor remains the primary controller for closed loop but certainly not the only sensor it needs.

    Just another point to add............There are a ton of really smart people here. Keep in mind please that as we present some information, most of us, speaking for myself, just want one question answered, "my bike is broke, what do I do to get back to riding?"
    1997 R1100RT (Restored Basket Case) , 1981 KZ 440 LTD (Restored Basket Case)
    1986 K75S(the beutch), 1993 K1100RS (blown engine), 1997 Chev Short Box (4x4 with an LT1)
    "You can easily judge the character of a man by how he treats those who can do nothing for him."

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