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

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.

If I ignore the coding plug issues and forget about oxygen sensors, I know that that Moronic requires only two systems to run in open loop: Timing signal and Oil Temp, or otherwise known as the ECT. After the Moronic sees other signals, it uses them to bring the system to closed loop, for optimized fuel and timing control. There is still no way to actively see closed loop in the Moronic. Closed loop is an assumption. Like all digital-analog convertors, refresh rate is too slow to see real-time data.

Oh I might mention that I was Bosch tech rep for about ten years.............

So my story; I got a CO Pot, installed in the existing harness. I was just curious.

I like my idle very low, about 800 rpm. It's a preference and no real need to weigh in and tell me that's not to spec.

I noticed on really warm days that throttle response was not "crisp" off idle but the solution was obvious. Bring the idle rpm up a bit and see what happened.

My replacement got me a CO Pot, oddly, they are used on a wide variety of manufacturers, including Mecerdes. The list goes on to include almost all the Germans and a bunch of Asian cars.

Now I have a "promo" $70.00 part and about the time it takes to crack a beer open, installed. I didn't touch the thing, no adjustment, just dropped it in. Idle dropped to about 700, bike makes a different sound at idle, call it happy. Takes off like a rocket. Great change coming off hot cruise to a stop, doesn't bounce off low idle, sounds happy.

My little 3200 to 3700 rpm "buzz", gone. It's just supposed to act on the Moronic open loop at idle. I thinking there is more to it.

Best part, no codes in the Moronic which makes me think, when I have a problem, it might be real.

I'm not going to get crazy about the "why's" as this was just for fun, like riding should be.

So if we referred to you as a "Bush tech rep", you wouldn't be offended?

That's funny, I'm cool with it.

I Love it..............I was also a Cat tech rep, what would that make me?

Bosch part#

BoschCat Rep,
Interesting. What were the little numbers on the CO Potentiometer? Where did it go in the harness?

rdhudson said:

BoschCat Rep,
Interesting. What were the little numbers on the CO Potentiometer? Where did it go in the harness?

Click to expand...

... switching to the Discovery Channel ...

+1, at the risk of turning this into one-of-those-dreaded serious threads ,

--what is the bosch part number?
--what coding plug is in your motorcycle?
--is there an oxygen sensor installed and plugged in?

... switching back to the Comedy Channel ...

RB

The Bosch part number is 0280101008. I have the yellow coding plug and the oxygen sensor is connected and working. On my bike, at the fuel tank vent valve, there was 3 wire connector with dead bugs in it. Obviously, the nights I spent trying to find the part that connects there was futile. I thought I had forgot something when I put the bike back together.

My bike came in about 6 boxes as the previous owner took it apart to rebuild the engine and got in over his head. There is always a reason why a good deal only seems like a good deal at the time. It took me a year to put it back together.

On some of the other vehicle manufacturers, they call it an idle enrichment valve. I made a simple breakout box and determined the Moronic does see it. With the breakout box, I can also see the timing change and the injector pulse width at real time when I use a frequency meter.

Since I don't care too much about fuel economy or maximizing performance, I thought, "what can it hurt to try installing a CO Pot?"

I don't think there's any harm in trying it. I'm not positive but with the Yellow plug installed it should ignore the CO pot. The reason is that warmed up and idling the fueling is determined solely by the O2 sensor and Closed Loop program. Happy Wanderer will probably test this.

Since you seem to have gotten a response from the pot, maybe that means your O2 sensor is dead.

If you have an old analog volt ohm meter, connect it to the black wire in the O2 sensor cable. At warm idle the needle should swing between about 0V and 0.8V and then 0V etc., once per second. If it is stuck near 0 or 0.8 then it may be bad.

Thanks for the p/n it will help someone.

I can see the frequency change with my O2 sensor. It climbs and falls pretty quick but the refresh rate in the Moronic is too slow to read it as fast as it can change.

I've read a lot more than I usually do and found a mixed variety of opinions on exactly what the CO Pot does. Same say a waste of space and others say it eliminates surging all the way to eliminating the distinctive popping an oilhead makes on decel.

In one of my Bosch books it describes it as only affecting idle mixture in closed loop. But we all know that Bosch, like Cat and especially Ford, only give you enough information in their publications to hang yourself.

I never had a surging problem and my popping on decel went away when I dropped my idle below spec. The biggest change I noticed was my idle seemed more stable and I have better poop in it when I take off from a standstill. Keep in mind, I like my idle way slower than spec.

Happy Wanderer has an Innovate LC-1 on his R1100RT so we now are getting a good idea just what the Motronic MA 2.2 does. Once warm, it is is Closed Loop at idle. Therefore, the CO Pot can't have an effect with the Yellow plug installed, perhaps during warm-up, but I doubt it.

With no Coding Plug or a 30-87a (GS, R), the Motronic (very likely) measures the voltage of the CO pot and adds or subtracts a few hundred microseconds to its digital calculation of injector pulse timing, since that is what it does with many other sensors. Therefore it only affects small injection times, like at idle. If it were a multiplication factor, like scale up by 5%, then everything would get bigger, not just idle. It is there to keep the carbon monoxide between 1 and 2%. Take this one to the bank. I'll be having Happy Wanderer confirm this too with his LC-1.

Active fault code=no closed loop

Maybe I just am not expressing myself very well.................

If the Moronic sees a fault, it will replace the missing value with a default value in the ROM or Read Only Memory. Input values that are missing may cause a "limp home condition" or cause the Moronic to default to known open loop values.

I had a fault, I put in a CO Pot, fault is gone, bike seems to run better. It's that simple.

I could not find anything that told me I needed a CO Pot or if it came with one out of the factory.

The first two laws of being a hired wrench: KISS-Keep it Simple Stupid, fix what you know isn't working first.

Other than data logging, there is no way you can see for sure if you are in closed loop. The refresh rate on the Moronic is 125 kbit/s. My fax machine is faster. My 1997 R1100RT doesn't meet the 1993 requirement for On Board Diagnostics or OBD. It didn't have to, it was not classified as vehicle according to the EPA. We can argue a ton about how a motorcycle is insured but they were categorized the same way as lawnmowers, chainsaws, boat motors and weedeaters.

The whole point of this string was to make it as simple as I could and relate a situation that was not well addressed anywhere that I could find.

Okay, so along the lines of KISS, you can tell for sure if you've entered Closed Loop.

Connect one lead of and analog (old fashioned) voltmeter to ground the other to the black wire of the O2 sensor. If Closed Loop is working the needle will swing, once per second, between 100mV and 800mV, at idle. Put your analog voltmeter on a 1 1/2 or 2 volt scale.

Roger, you are killing me here dude................

Take a single wire O2 sensor and warm it up with a torch. Connect the single wire to the positive on an analog meter, negative on the body. Blow on it with an air compressor then take some oxygen from a cutting torch. It will change voltage if it works. The O2 sensor is only one part of the Moronic's need for closed loop.

Just back in town and catching up on some threads. Here is some info that may be of interest.

- In 95 and 96 Canada received Euro configured bikes. They had no cat code plug (you will not find it in the fiche for those years) and were equipped with a Bosch CO pot. They also had no O2 sensor. I know this for a fact as I owned one and wrenched it till it quit surging.

- Starting in 97 BMW began shipping US models to both the US and Canada. These bikes have no CO pot and a yellow (golden?) CCP which jumpers 30 (gnd) to 86 and 87a I believe. Roger posted a list of CCP configurations somewhere here earlier.

- RTs with a CO pot are set to idle at 1000 to 1100 RPM and the CO pot is set using a gas analyzer. The target emission is 1.8% with the bike fully warmed up. This info is in the factory manual methinks.

- Don't know how you went about setting your idle lower but another important setting is the TPS. The optimum TPS voltage for the RT at 1100 RPM is 0.685 mV. That is half way between .670 and .700 (min - max). This is where the Motronic expects to find the correct idle speed and uses this and other inputs to determine injector pulse width.

It is totally possible to measure exactly when an oilhead goes into closed loop. Roger has done it hundreds of times by now and I also have done it using the same Innovate Powersports LC1 wideband O2 sensor which has data logging capability. The logging intervals are programmable to instant, 1/12th, 1/6th and 1/3rd of a second. That is plenty fast enough. Graphs of this are posted in the Wideband O2 sensor thread.

Dieselyoda said:

Take a single wire O2 sensor and warm it up with a torch. Connect the single wire to the positive on an analog meter, negative on the body. Blow on it with an air compressor then take some oxygen from a cutting torch. It will change voltage if it works. The O2 sensor is only one part of the Moronic's need for closed loop.

Click to expand...

So you are saying pulling the exhaust system off the bike, removing the O2 sensor, hauling out your blowtorch and _then_ connecting a meter is easier than just measuring it right on the bike you are trying to fix?

I think I'll skip right over to my meter and save the blowtorch trick for the box of maybe dead sensors in the corner junk pile.

happy wanderer said:

So you are saying pulling the exhaust system off the bike, removing the O2 sensor, hauling out your blowtorch and _then_ connecting a meter is easier than just measuring it right on the bike you are trying to fix?

I think I'll skip right over to my meter and save the blowtorch trick for the box of maybe dead sensors in the corner junk pile.

Click to expand...

Boy, I didn't want to get this thread complicated and adversarial. An O2 sensor creates its own voltage that is sensed by an ECM.

You are absolutely right, you can confirm closed loop by data logging. You can't see it real time with these antique digital-analog convertors.

If you look at real time with a fast interface on a CAN, Controller Area Network, you will see that anytime you go WOT, Wide Open Throttle, it goes to open loop, just for a few milliseconds.

I don't know specifically about the Moronic 2.2 and I don't care but almost all ECM's will stay open loop with a hard fault code. I had one, I installed a CO Pot that may or may not have been needed, the bike runs better, end of story.

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

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.

Side question: Dieselyoda, can you share the details and maybe a pic of your Motronic breakout box?

I would love to get a picture, I will try

JamesInCA said:

Side question: Dieselyoda, can you share the details and maybe a pic of your Motronic breakout box?

Click to expand...

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.....................................

Dieselyoda said:

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.
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Stay to the basics, look for the simple stuff and fix the problem you know first.

Click to expand...

OK. Let's do that . Stay with the basics.
What was the fault code you found that you fixed with a CO pot?