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post #1 of 21 Old Oct 10th, 2005, 7:16 pm Thread Starter
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Limp Home Mode

I just got back from a great ride around the Big Bend area, but I on the way down there my back went into limp home mode, which I didn't know anything about. We happened upon a BMW mechanic who told us about it and suggested removing the ground wire from the battery to reset the motronic. This cleared the lime home mode and I assumed that it must have been caused by bad gas or something. We rode all weekend with no trouble, and then on the way home it did it again. I tried resetting it again and it would go back into limp home again within 5 minutes, so there is obviously something wrong. I know that the dealer could tell me in five minutes what the problem is, but that would mean I would have to take it to the dealer, pay the dealer, and miss all the fun of working on the bike yet another time. I thought that I would attempt to check all the suggestions you guys could come up with before I resort to the dealer. Just for info, I did the cannisterectomy a couple of weeks before this happened, so it might be related. I'm contemplating replacing the fuel filter, reinstalling the cannister, inspecting the fuel tank vent tube, and possibly testing the O2 sensor. Any suggestions would be appreciated.

"One can never consent to creep when one feels an impulse to soar" - Helen Keller

2000 Canyon Red "Barcalounger" K1200LT
2003 F650GS
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post #2 of 21 Old Oct 10th, 2005, 10:32 pm
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There's nothing I can think of associated with the canisterectomy that could cause a "limp-home" mode -- *except* maybe if the hose to the intake is open, which would be the equivalent of a vacuum leak. If the O2 sensor/Motronic couldn't adjust the mixture far enough to get the mixture into the right range, then the computer may default to the limp mode.

The only other things that comes immediately to mind are the usual Moronic inputs -- the O2 sensor itself, the throttle position sensor (or more likely, its connector/wiring), coolant temp sensor.

You probably won't like to hear this, but this is the sort of thing that you could spend hours and $$$ chasing down the cause -- you may end up *far* less frustrated by taking the extra now time to get a diagnostic read to pin-point the problem -- so you can replace it. I'd be very surprised if you get charged more than a few bux to simply get the computer plugged in and read.

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post #3 of 21 Old Oct 13th, 2005, 9:30 pm
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Grif sez, if it's limp, try Viagra.

Seriously, let us know what the diagnostic reads. I believe you may have a first, Tom.
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post #4 of 21 Old Oct 14th, 2005, 9:57 am Thread Starter
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Well, as a matter of fact I did take it to the dealer yesterday. First, they quoted me $35 to read the fault code, and then when I got there, they said that they had a 1 hour minimum and that they would do additional analysis beyond the computer, so it would cost me $83 total. The computer said the O2 sensor was bad, and also something about the Lambda gate reaching the end of its travel. Sorry I don't have the sheet in front of me, so I don't remember exactly what it said. Bottom line is, they reset the computer and it ran fine, so they took it on a couple of test drives and declared everything OK. Which is basically what happened to me in Alpine. Now I'm debating whether I should order an O2 sensor or wait until the failure occurs again. I'm also pretty certain I have a leak in the breather tube due to the oil residue on the fourth throttle body. Any thoughts on the likely hood that the O2 sensor really is OK?

"One can never consent to creep when one feels an impulse to soar" - Helen Keller

2000 Canyon Red "Barcalounger" K1200LT
2003 F650GS
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post #5 of 21 Old Oct 14th, 2005, 10:29 am
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Quote:
Originally Posted by tomc1394
Well, as a matter of fact I did take it to the dealer yesterday. First, they quoted me $35 to read the fault code, and then when I got there, they said that they had a 1 hour minimum and that they would do additional analysis beyond the computer, so it would cost me $83 total. The computer said the O2 sensor was bad, and also something about the Lambda gate reaching the end of its travel. Sorry I don't have the sheet in front of me, so I don't remember exactly what it said. Bottom line is, they reset the computer and it ran fine, so they took it on a couple of test drives and declared everything OK. Which is basically what happened to me in Alpine. Now I'm debating whether I should order an O2 sensor or wait until the failure occurs again. I'm also pretty certain I have a leak in the breather tube due to the oil residue on the fourth throttle body. Any thoughts on the likely hood that the O2 sensor really is OK?
I'm sort of surprised about getting charged for that -- guess it's a dealer-by-dealer thing

As to the O2 sensor being bad -- it's bad The 'lambda" thing refers to the output of the sensor -- the "reaching the end of its travel" means that the O2 sensor output is beyond the end of the normal operating range, i.e., it is no longer providing useful data when fully warmed up. Bottom line, you *will* default back into the "limp home" mode shortly (when the Moronic figures out that it can't rely on the O2 sensor for mixture control, it shifts to a default fuel injeciton map which ignores the O2 sensor). Sorry for the bad news, but it's time to order up a new sensor. A search on the old site such turn up some pics/tips for replacement (a pita, given its well-buried location just upstream of the catalytic converter in the exhaust).

Mark Neblett
Fairfax, VA
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post #6 of 21 Old Oct 14th, 2005, 10:32 am
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Quote:
Originally Posted by tomc1394
The computer said the O2 sensor was bad, and also something about the Lambda gate reaching the end of its travel. Now I'm debating whether I should order an O2 sensor or wait until the failure occurs again. I'm also pretty certain I have a leak in the breather tube due to the oil residue on the fourth throttle body. Any thoughts on the likely hood that the O2 sensor really is OK?
Usually when the computer calls a sensor as bad it does it looking at the sensor over a period of time. The program calls the most likely offender and although you can reset and go replacing the O2 will get you past the next hurdle in the troubleshooting.

I'm sure you will do the procedure so it's not like your going to pay $400 for something that you are guessing at. I have had at least two issues on my M/Vs that the computer called that sensor bad and eventually I had to replace them and it fixed the problems. I tried TSBs and loaded new code and spent more $ chasing a cheaper fix but eventually I bought the sensor.

jm2cw

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post #7 of 21 Old Oct 14th, 2005, 11:20 am Thread Starter
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I think I pretty much knew deep down that I had to buy the sensor. One of the things that disappoints me is the fact that the dealer technicians can't make the same assessment that you guys can. I'm really glad I can rely on this forum and the expertise and experience of some many guys like you. Thanks for all you help. I'll order the sensor today.

"One can never consent to creep when one feels an impulse to soar" - Helen Keller

2000 Canyon Red "Barcalounger" K1200LT
2003 F650GS
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post #8 of 21 Old Oct 14th, 2005, 11:34 am
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Just curious Tom, how did you know the bike went into the limp mode? Any lights or other warnings or was it simply the way the bike was running?

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post #9 of 21 Old Oct 14th, 2005, 12:07 pm Thread Starter
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Originally Posted by CWF
Just curious Tom, how did you know the bike went into the limp mode? Any lights or other warnings or was it simply the way the bike was running?
Funny you should ask. The first thing I noticed was that the bike was idling rough, and making too much noise, including a knock. I first thought it might be bad gas, or something. Then I discovered my fuel mileage was in the tiolet. It dropped from an average of 50mpg to as low as 27mpg. I was on a trip to meet Dave Moore in Alpine to ride Big Bend for the weekend, so when I got there, we started poking around and discovered that the spark plugs were black. We tried some fuel injector cleaner (standard straw grasping technique) and rode about 80 miles. To make a much longer story not quite so long, we met up with a former BMW mechanic and he explained the limp home mode, which I was totally unaware of. He suggested disconnecting the battery for five minutes to reset the computer, which actually worked. It didn't go back into limp home mode until I was on my way home.

There is no indication from the computer that anything is wrong. In fact, I'm amazed at how well it runs considering the mode that it's operating in. The first indication is really the fuel mileage. What I found is that the rough idling doesn't really start until the spark plugs start to foul. There are some slight changes in the way the engine runs, but its hard to detect that as an indication of a problem.

"One can never consent to creep when one feels an impulse to soar" - Helen Keller

2000 Canyon Red "Barcalounger" K1200LT
2003 F650GS
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post #10 of 21 Old Oct 14th, 2005, 12:21 pm
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Quote:
Originally Posted by tomc1394
we started poking around and discovered that the spark plugs were black.
This confirms the Moronic gave up on the O2 sensor and went to the default map -- the default is conservatively rich to protect the engine.

Quote:
Originally Posted by tomc1394
He suggested disconnecting the battery for five minutes to reset the computer, which actually worked. It didn't go back into limp home mode until I was on my way home.
Another confirmation -- as the previous poster stated, the Moronic doesn't instantly drop to the default map -- it waits long enough to confirm that it's really not receiving the sensor signal. You found out how long on the way home

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post #11 of 21 Old Oct 14th, 2005, 1:57 pm
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Quote:
Originally Posted by tomc1394
I think I pretty much knew deep down that I had to buy the sensor. ........ I'll order the sensor today.
Did you see this... from another post from some guy parting out beemers...
Has a new o2 sensor


BeemerBoneYard

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post #12 of 21 Old Oct 14th, 2005, 6:02 pm
 
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02 sensor

when the sensor is tested on the GT-1 it is either in the proper range or it is not and needs to be replaced, I have never seen the " reached the end of it's limit" or whatever that statement said. weird?
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post #13 of 21 Old Oct 17th, 2005, 7:44 pm
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Hey Tom, sorry about the dealer rip-off (Another reason to move to Texas?). But you have the best advice in the world right here. Have you looked at where the O2 sensor is located? Easy to change? I honestly don't know where it is - on the exhaust somewhere. If you do it yourself, take some pictures and post them here. We'll all learn from your experience. Thanks amigo!

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post #14 of 21 Old Oct 17th, 2005, 9:03 pm
 
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O2 sensors rarely die immediately, it's usually a intermittent open on the wiring harness that leaves the sensor itselg, likely from flexing and thermal cycling. The O2 sensor wire goes open, no current and the computer after a brief period determines it is dead and executes (the engine light on a car), and limp in mode.

Resetting the computer will cause it to re-evaluate the system and if the problem is intermittent, usually is with O2 sensors for the first while, it will buy you time. Cars will store the old code for a number of miles or time before cancelling, an ODB2 reader can clear it on a car.
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post #15 of 21 Old Oct 18th, 2005, 9:06 am Thread Starter
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Just to let you all know, I've ordered a sensor and a new distibution hose, but it may be a couple of weeks before I get them. I found a paper someone posted (don't remember who at the moment) about changing the sensor differently than the service manual does it. He claims its a 30 minute problem. I expect the distribution hose to be a lot more work. BTW, the error message from the computer was that the O2 sensor was a direct short to ground. It sounds like the failure mode may be a little different than the typical failure.

"One can never consent to creep when one feels an impulse to soar" - Helen Keller

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post #16 of 21 Old Oct 18th, 2005, 12:34 pm
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Quote:
Originally Posted by tomc1394
BTW, the error message from the computer was that the O2 sensor was a direct short to ground. It sounds like the failure mode may be a little different than the typical failure.
Wait a minute! That's a very important data point!

While waiting on the sensor, I'd be tracing over *every single mm* of the wires from the sensor back up the harness. Bruce7 is right -- these things do not tend to go instantly bad. It would be a shame to waste the money/time replacing the sensor when the fix may be nothing more than a simple chaffed wire mending!

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post #17 of 21 Old Oct 18th, 2005, 2:59 pm
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Quote:
Originally Posted by mneblett
Wait a minute! That's a very important data point!

While waiting on the sensor, I'd be tracing over *every single mm* of the wires from the sensor back up the harness. Bruce7 is right -- these things do not tend to go instantly bad. It would be a shame to waste the money/time replacing the sensor when the fix may be nothing more than a simple chaffed wire mending!
...and then possibly ending up with the same problem if it was a wire issue. Wouldn't that be a pisser.

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post #18 of 21 Old Oct 30th, 2005, 3:47 pm
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Gentlemen:
I had this exact same problem at the beginning of the riding season(2005), at first my dealer claimed the problem was one fouled spark plug, so they changed them all. One week later my bike was back to running rough, chuggin gas like crazy. I dropped it back at the dealer a week later. It took them 4 days to find out it was the O2 sensor, and my battery died.
So I agreed to the battery and O2 sensor, and Herman the German cleaned out my wallet. Yes, it ran great. The bill was,,,,, lets not go there.
I had a planned trip that weekend with a group, and wanted to see if the bike was really back on track. One of the other riders in our group has a 99KLT, and we both filled up in Traverse City, MI and headed out, when we returned to the camp ground with 280 miles on odometer, I wanted to see if the computer was right (not even close) and filled up and compared my mileage with that of my friends. Can you believe it, I got 57.6 mpg and my friend got 58.0 mpg, note the fuel light had not come on yet.

So, by reading the forums I now know my bike was in limp home mode, and it had been there for a while. FYI my bike was running so poorly, I had to put rubber shims between some of the body parts to keep the noise down.
I wish I had another dealer around, I would like to take my business else where.

(This is my first reply, hope I did it correclty)

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post #19 of 21 Old Oct 30th, 2005, 6:54 pm
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Red face

I had something similar happen to my 2002 when it had 4,000 miles on it, while going to CCR 2003. I'd just bought Amoco gas, took off and it lost 30% power just as I left the station. Sounded like it was running on three cylinders. When I got the the CCR, I put in some STP gas treatment thinking I had water contamination in the gas. It then ran great for about 20 miles, then started doing the same thing again. That night, Stuart and I took out the plugs in the hallway outside the ballroom of the hotel and found the #3 plug fouled.

The next morning I rode it back to Atlanta. Hell, why not, it was 9 months old and under warranty and I figured it was as good a time as any to blow it up. Funny thing is that it ran great at 80 mph, but ran like @#$! at any other speed. My mpg was 27, usually 43. Turns out that my #3 fuel injector went bad and ruined the 02 sensor. BMW of ATL replace the injector, 02 sensor and 4 plugs. No problem since. You might want to check that #4 injector. BMW of Atlanta told me they had never seen an injector fail before. I'd like to mention that they loaned me a 2000 LT to ride back to the CCR and let me keep it until my bike was repaired. (I put 1,500 miles on it) Great folks at BMW of Atlanta.

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post #20 of 21 Old Oct 31st, 2005, 8:24 am Thread Starter
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Our dealer here has been more like Herman the German, but we're getting a new one in December. I'm sure they won't be any cheaper, but the expectations are that they are more professional and fair. I just finished putting in the O2 sensor this weekend. I rode 168 miles and averaged 55 mpg, which included at least 50 miles at 75 mph, which is typically 45-48 mpg on my bike. It seems to be running very well, but I will pull the spark plugs tonight to see if they are all burning OK. Thanks to everyone for your help and advice. I couldn't own a bike like the LT without a web site like this one.

"One can never consent to creep when one feels an impulse to soar" - Helen Keller

2000 Canyon Red "Barcalounger" K1200LT
2003 F650GS
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post #21 of 21 Old Nov 6th, 2005, 10:11 pm Thread Starter
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I just finished installing the new distribution hose and thought I should share one last thing. My distribution hose had 3 separate and independent tears in it. It was starting to make quite a mess. After looking at it, I'm sure there are a lot of bikes out there with this problem and don't even know it. The only way to tell is if you see oil on the rear throttle body, and generally around the top of the engine. If you don't look for it, you won't find it. At any rate, I would recommend that you look carefully at the throttle bodies any time you take the left side cover off. It was a lot more work to change out than the O2 sensor, and it doesn't affect the performance of the bike, but it is a shame to have such a nice looking bike get oil gunk all over the engine.

Again, thank you all for the feedback.

"One can never consent to creep when one feels an impulse to soar" - Helen Keller

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