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Discussion Starter #1
Hello,
I recently got a 2004LT with 30K miles, in excellent general condition. The bike runs very well overall. It does tend to have a high idle when hot (it starts with a normal 1000 or so RPM when cold, then stabilizes around 1500 RPM hot). No other symptoms. Gas consumption is higher then 45 MPG when riding smoothly on regular highway, higher when in town and pressing on, but this is probably normal.. Very nice, smooth bike...

Out of curiosity, I just got an adapter for my ODB2 sensor, as well as the Motoscan Basic app which connected very well and gave me 3 error codes..:
  • 1506 High idle (not a surprise..)
  • 335 (crankshaft position A circuit) and 385 (crankshaft position B circuit). The detailed sub message is the same for both and is 04 "No signal or value"

Has anyone experienced this set of circumstances? If so, how did you address?
Outside of having to remove all plastic and the tank, replacing the Hall Sensor doesn't seem too complicated in itself, if the bike doesn't require an ignition timing reset/calibration.
I would like to avoid a $$$ visit to my BMW garage if at all possible..

Thank you,
 

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Hello,
I recently got a 2004LT with 30K miles, in excellent general condition. The bike runs very well overall. It does tend to have a high idle when hot (it starts with a normal 1000 or so RPM when cold, then stabilizes around 1500 RPM hot). No other symptoms. Gas consumption is higher then 45 MPG when riding smoothly on regular highway, higher when in town and pressing on, but this is probably normal.. Very nice, smooth bike...

Out of curiosity, I just got an adapter for my ODB2 sensor, as well as the Motoscan Basic app which connected very well and gave me 3 error codes..:
  • 1506 High idle (not a surprise..)
  • 335 (crankshaft position A circuit) and 385 (crankshaft position B circuit). The detailed sub message is the same for both and is 04 "No signal or value"

Has anyone experienced this set of circumstances? If so, how did you address?
Outside of having to remove all plastic and the tank, replacing the Hall Sensor doesn't seem too complicated in itself, if the bike doesn't require an ignition timing reset/calibration.
I would like to avoid a $$$ visit to my BMW garage if at all possible..

Thank you,
FIRST, there was no such thing as mandatory OBD2 compatibilty for mortorcycles prior to 2018 (mainly requested by European-Union). So any OBD2 tool / adapter that you use on these older BMW motorcycles (or any other brand) tries to map the proprietary fault codes of the ECU (BOSCH Motronic in this case).

Since OBD2 has specific mandatory category of codes depending on the source / sensors / sub-system, the mapping of these codes means little when compared to the orginal BOSCH codes.

As far as I know, only 2 tools will give the proper codes AND the proper BOSH error messages: either the dealer's computer OR a GS911 (made by a 3rd party and available to the public).

In your particular case above, the 2 crankshaft positon circuit errors (335 , 385) would probably corresponds to a normal fault when the engine is not running.
In BOSCH Motronic codes on a GS911 (or dealer's computer), these always appear as:
1) code 821: Hall sensor 1, no signal – this fault will always occur if engine not running or engine not cranked before reading Fault codes
2) code 901: Hall sensor 2, no signal – this fault will always occur if engine not running or engine not cranked before reading Fault codes

Finally, for the other OBD2 code 1506: neither the code or the description matches to a BOSCH Motronic codes - I have compiled a fairly long list ovwr the last 18 years.

On these K1200LT (and K1200RS), as they age, by far the most common cause of high idle is caused by unwanted intake air leaks. Under the throttle-bodies and the 4 intake manifolds, there are 4 O-rings and 4 rubber stubs that will often crack causing unwanted air-leaks. In addition, there are 4 small vacuum tubes AND 1 larger 4-into-1 black rubber hose behind the throttle-bodies that will also crack after 8 to 10 years.

Almost as common as the unwanted intake air-leaks: over the years there has been quite a few case of incorrectly routed OR adjusted throttle-cables (free play) causing the same symptoms. Unless you intend to bring it to the dealer for large $$$, I would strongly suggest that you buy the CLYMER shop manual available for the K1200LT / K1200RS. With this manual and the expert tips here, assuming you have some mechanical abilities, you can fix almost anything yourself on these.
 
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@EricP , sailor gave you a great answer but I'm a simple guy and, wondering if maybe this is your first BMW, do you know about the easy throttle position reset procedure that we do every time the battery is disconnected? If it's a new bike to you, can't hurt to try it. If it doesn't help then, yeah, probably an air leak somewhere.

Throttle Reset
1. switch ignition on but don't start the bike
2. twist the throttle to fully open then fully closed
3. twist it again - full open to full closed
4. switch ignition off

That's it! This silly little procedure "teaches" the ECU the limits of the throttle.
 

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Discussion Starter #4
Thank you both for your fast response!

Drone,
Yes, first BMW bike... Thank you for sharing this as a first step.. I tried the reset you mentioned, but it didn't make a difference. Still 1500 RPM idle when hot...

Sailor,
Thank you for taking the time to share this comprehensive guidance! I will now hunt for vacuum leaks.
 

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Hello,
I recently got a 2004LT with 30K miles, in excellent general condition. The bike runs very well overall. It does tend to have a high idle when hot (it starts with a normal 1000 or so RPM when cold, then stabilizes around 1500 RPM hot). No other symptoms. Gas consumption is higher then 45 MPG when riding smoothly on regular highway, higher when in town and pressing on, but this is probably normal.. Very nice, smooth bike...

Out of curiosity, I just got an adapter for my ODB2 sensor, as well as the Motoscan Basic app which connected very well and gave me 3 error codes..:
  • 1506 High idle (not a surprise..)
  • 335 (crankshaft position A circuit) and 385 (crankshaft position B circuit). The detailed sub message is the same for both and is 04 "No signal or value"

Has anyone experienced this set of circumstances? If so, how did you address?
Outside of having to remove all plastic and the tank, replacing the Hall Sensor doesn't seem too complicated in itself, if the bike doesn't require an ignition timing reset/calibration.
I would like to avoid a $$$ visit to my BMW garage if at all possible..

Thank you,
Hi! Good luck with your first Beemer! The last two paragraphs of John/sailor's post are most important... when you remove the Tupperware, have your Clymer manual, or factory manual handy and can aim a flashlight at the top of the engine block you will probably see an oily mess which will also let you know it is time to replace all the rubber, and plastic bits besides plug wires, fluids, etc. It's a great motorcycle which just takes some efforts to get it up to speed on making it last and safe... as long as you can turn a wrench you will save a lot of cash in the process. Have you checked the dates on the tires? If you plan to keep it buying the GS911 is a good investment!
Also, there are so many talented people to ask questions here. They have helped me a lot! Cheers!
 

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Discussion Starter #6
Hi! Good luck with your first Beemer! The last two paragraphs of John/sailor's post are most important... when you remove the Tupperware, have your Clymer manual, or factory manual handy and can aim a flashlight at the top of the engine block you will probably see an oily mess which will also let you know it is time to replace all the rubber, and plastic bits besides plug wires, fluids, etc. It's a great motorcycle which just takes some efforts to get it up to speed on making it last and safe... as long as you can turn a wrench you will save a lot of cash in the process. Have you checked the dates on the tires? If you plan to keep it buying the GS911 is a good investment!
Also, there are so many talented people to ask questions here. They have helped me a lot! Cheers!
Thank you Kbob12! Yes, I did check the tires. They are brand new in terms of mileage, and fairly new in terms of age (3 years DOT code). I had many bikes over the years (all street bikes) but no BMW. I still have a 1999 900 Triumph - which appeared so incredibly small and light as I rode it back last week-end, after starting to get use to the LT..-
 

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Thank you Kbob12! Yes, I did check the tires. They are brand new in terms of mileage, and fairly new in terms of age (3 years DOT code). I had many bikes over the years (all street bikes) but no BMW. I still have a 1999 900 Triumph - which appeared so incredibly small and light as I rode it back last week-end, after starting to get use to the LT..-
Good to hear! And, you are welcome. Keep the front wheel straight when starting and stopping... may be the best advice for any K1200LT rider. Otherwise, you will see how fast it wants to fall asleep!
My big Harley feels like a toy compared to the KLT! The KLT is my favorite motorcycle of all the dozens I have owned over the years! I also enjoy working on it when I have to!
 

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Discussion Starter #8
So, taking @sailor 's guidance and Clymer-in-hand, or so to speak, spent a good part of yesterday trying to find what may be going on with this high idle.. At the end of the day, the day the symptoms are still here, but for sure have developed a much larger knowledge of the bike...

  • Checked throttle cables setting. Had to only very slightly adjust hot setting for one of them, but all looks good here.
  • Throttle bodies are actually very clean. A bit dusty if anything, which confirms background shared by previous owner (bike always kept in, not ridden "at all" in the rain etc).. The throttles appear to close all for all. Original paint match mark is still there and has not tampered with.
  • All rubber fittings appear to be very clean, piping doesn't show any cracking and is still soft and flexible (both small vacuum lines and larger ones)
  • No vacuum leak detected. Even after thorough carburetor cleaner spray in different locations, multiple times, couldn't detect anything there
  • Live signals received through the Motoscan ODB2 app show what appears to be normal as far as I can tell (and error codes cleared once running as Sailor suuggested). The O2 / lambda sensor behaves normally when hot (fluctuates continuously between ~ 0 and ~800 mV, and sends its signals to the Motronic as expected. Engine temperatures increases and then stabilizes fans on as expected.
  • Took the gas tank out and checked the air filter which is clean/new as mentioned by previous owner

So the symptoms are still the same and appear to be stable:
  • The bike starts up as expected with idle when cold at ~1050 RPM
  • As the engine gets in temperature and starts interacting with Motronic, the idle gradually increases to 1450 to 1500 RPM and stays stable there.

The bike does run very smooth. Very nice indeed. I can ride it like this without problems, but it doesn't feel right to me that the idle should stay at this level.

Any other thoughts, if some of you have experienced these symptoms? Maybe something going on with the Throttle Positioning System or the Idle Control Valve Throttle Actuator?

Thanks all,
 

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So, taking @sailor 's guidance and Clymer-in-hand, or so to speak, spent a good part of yesterday trying to find what may be going on with this high idle.. At the end of the day, the day the symptoms are still here, but for sure have developed a much larger knowledge of the bike...

  • Checked throttle cables setting. Had to only very slightly adjust hot setting for one of them, but all looks good here.
  • Throttle bodies are actually very clean. A bit dusty if anything, which confirms background shared by previous owner (bike always kept in, not ridden "at all" in the rain etc).. The throttles appear to close all for all. Original paint match mark is still there and has not tampered with.
  • All rubber fittings appear to be very clean, piping doesn't show any cracking and is still soft and flexible (both small vacuum lines and larger ones)
  • No vacuum leak detected. Even after thorough carburetor cleaner spray in different locations, multiple times, couldn't detect anything there
  • Live signals received through the Motoscan ODB2 app show what appears to be normal as far as I can tell (and error codes cleared once running as Sailor suuggested). The O2 / lambda sensor behaves normally when hot (fluctuates continuously between ~ 0 and ~800 mV, and sends its signals to the Motronic as expected. Engine temperatures increases and then stabilizes fans on as expected.
  • Took the gas tank out and checked the air filter which is clean/new as mentioned by previous owner

So the symptoms are still the same and appear to be stable:
  • The bike starts up as expected with idle when cold at ~1050 RPM
  • As the engine gets in temperature and starts interacting with Motronic, the idle gradually increases to 1450 to 1500 RPM and stays stable there.

The bike does run very smooth. Very nice indeed. I can ride it like this without problems, but it doesn't feel right to me that the idle should stay at this level.

Any other thoughts, if some of you have experienced these symptoms? Maybe something going on with the Throttle Positioning System or the Idle Control Valve Throttle Actuator?

Thanks all,
Based on working on these K1200 for 18 years AND following 3 pretty serious forums, I would say there is a 50 to 75% probability your current assumptions are incorrect. In more than 50% similar cases, after trying a bunch of other stuff the owner eventually did what we told him to do: remove , clean some corrosion (cylinder-head to manifold) , inspect and replace all these rubber intake parts. In my humble opinion, for cases like this, we have past evidences that shooting carb cleaner (or other substances) does NOT detect all intake air leaks. See attached photos for common issues you will find if you really go deeper in your search for damaged rubber parts...

OF course, logic clearly dictates to also try the simple / cheaper stuff first, so in case your issue is not air-leaks, it would be appropriate to also try the TPS values / setting in case it has been messed up by someone before you. This can be done with GS-911 or with a Multimeter: make sure you fully understand attached PDF document before you embark on this OR go to the dealer and ask them to check TPS setting.

The other "next probable"cause would be an incorrectly set TVA (idle actuator motor) or a defective one (although not common). I have another similar PDF document to guide you with this... but I would suggest you try with TPS first.

172060



172061


172062


172063
 

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Thank you Sailor! This gives me some further direction.
Everything John/sailor said above, I did... and it corrected my issues with high idle. Trust the people here. They know.
So, while you have it apart replace all the rubber and plastic and o-rings.
Meanwhile, send your fuel injectors out for cleaning to Mr. Injector in Idaho for some added cheap insurance! Check them out here: Mr Injector ...they will replace o-rings and clean your injectors and give you test results from their procedures.
You will be happy you did everything down the road, too!
Happy New Year!
 

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Discussion Starter #13 (Edited)
Hi all,
Just a note to close this post. I finally got the parts and had to go in a few times. I have now developed quite a bit of dexterity taking all Tupperware off and putting it back on.

As Sailor pointed, I first took care of the rubber parts. I found a cracked breather hose. It let a bit of oil sipping out, but not much yet. The engine block was still clean. Changed the O rings (removed a bit of corrosion underneath) and rubber boots over the manifolds as well as all the small rubber hoses. I put everything back together and... still had the same symptoms (high idle of ~1500 RPMs).

I then went in a got more education on both TPS setting and TVA behavior. Since I intend on keeping the bike, I got a GS911, which allowed me to see that it was not set right at all. I brought it back outside of red zone. I also found out that although the TVA piston was operating well, the internals did not make contact. I took a chance and got a used TB on EBay, removed the TVA and installed it on my bike which now runs as intended. Very smooth, idle around 1050 and gas mileage jumped from high 30's to the 50's.

Thank you all again for the guidance! Thank you again especially to Sailor for the documents you uploaded through the years (TB, TVA, TPS). Very useful!
 

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Hi all,
Just a note to close this post. I finally got the parts and had to go in a few times. I have now developed quite a bit of dexterity taking all Tupperware off and putting it back on.
....
....
Thank you all again for the guidance! Thank you again especially to Sailor for the documents you uploaded through the years (TB, TVA, TPS). Very useful!
Glad you got this fixed.
Working and cleaning all this bits / parts requires time and patience but it does pay off at the end if you are a "fix it myself" type of guy. Based on my experience you should be good for another 8 to 10 years depending on type of usage and storage conditions before any of these intake rubber components needs attention again.

Another important "potential" problem area for older K1200 (if this has not been done yet) are the 2 internal short hoses inside the tank (between fuel filter and pump). With increased amount of Ethanol in common fuel, these have often failed after 8 to 10 years on average. Same story for the OEM black plastic fuel quick connector - just below tank to connect both fuel hoses.

If you do not have clear maintenance history about these 2 items above, you should plan to do both VERY SOON. These has been a few cases of fire caused by leaking fuel tank quick-connectors. The internal short fuel hoses issue is not as critical but it would leave you with a sudden dead engine - you cannot really fix these hoses on the side of the road - not a fun ride at all unless you enjoy being towed ;-)
 
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Discussion Starter #15 (Edited)
Thank you. The quick disconnect were changed before to the metal ones. In fact the previous owner had probably shortened the fuel lines in the process as they were quite constricted. I ended up replacing the hoses to some pre-shaped ones which fit perfectly (cut to keep just the elbow section).
Here is the post if it can help someone else:

172918




While "in there" I also removed the canister, removed the alarm (it was draining my battery down) as well as the radio (now a nice storage box as per several posts on this forum).

I have not done the lines inside the tank though... I future project to add to the list :)

Thanks again.
 

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Thank you. The quick disconnect were changed before to the metal ones. In fact the previous owner had probably shortened the fuel lines in the process as they were quite constricted. I ended up replacing the hoses to some pre-shaped ones which fit perfectly (cut to keep just the elbow section).
Here is the post if it can help someone else:

View attachment 172918



While "in there" I also removed the canister, removed the alarm (it was draining my battery down) as well as the radio (now a nice storage box as per several posts on this forum).

I have not done the lines inside the tank though... I future project to add to the list :)

Thanks again.
That is nice to have a pre-molded hose like that but just to make sure some don't think they can use that nice U bend inside the tank, this is not submersible line so use only as replacement for external tank lines. You need J30R9 or better for inside and this is J30R7. I may buy one myself as the loops I have are larger than I want.
 
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Discussion Starter #17
Absolutely. Thank you bmwcoolk1200 for the precision and additional information!
 
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