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I have a 1999 LT and it appears from reading I would like to try this brown wire trick. I have read several threads about do's and dont's with the wire but i can not find a actual thread that shows the location of this wire. I have the hesitation it hot weather etc it mentions.

So please is there a pic or good description out here? Second question, how many of you all that did it ended up re-connecting it?

Thanks

Bill
 

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Short answer - No brown wire on a 99 LT.

You can pull the temp sensor though.
 

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The brown wire was on a few late year model 01's until 03 sometime in production. After that they changed the motronic. The 99's through mid 01's had the original motronic but you can unplug the temp sensor by the radiator cap, as I have mine.
You should run 91+ octane after that though.
 

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amarider said:
The brown wire was on a few late year model 01's until 03 sometime in production. After that they changed the motronic. The 99's through mid 01's had the original motronic but you can unplug the temp sensor by the radiator cap, as I have mine.
You should run 91+ octane after that though.
What is the advantage to doing that? I have read about the brown wire and since I also have a 99 I just disregarded. I have never experienced any problems touring during the warmer weather.
 

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Brínging this probably ancient topic on top but I noticed first time hesitation with my -99 and I would like to confirm if I have this problem or do I have to look elsewhere.

So has somebody running early model installed a switch in temp sensor line? Just to be able to switch it on/off? Does Motronic recover from "adding the sensor on the fly or do you have to a) reset fault code b) restart bike? Anyone have any experience?
 

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C-A-D said:
Brínging this probably ancient topic on top but I noticed first time hesitation with my -99 and I would like to confirm if I have this problem or do I have to look elsewhere.

So has somebody running early model installed a switch in temp sensor line? Just to be able to switch it on/off? Does Motronic recover from "adding the sensor on the fly or do you have to a) reset fault code b) restart bike? Anyone have any experience?
The Moronic doesn't do anything like set a code or required a "reset" in response to disconnecting or re-connecting the temp sensor (it's just an input that's either present or not) -- but I don't favor this method on a '99; IMO, it's better to remove the trunk and cover panel and remove the "cat code plug."

Removing the cat code plug tells the Moronic to use an alternate fuel injection/ignition map which does not have the ignition timing retarding in one specific condition -- a combination of high ambient air temperature, low rpm, and a relatively high throttle setting (corresponding to a significant load on the engine -- a condition in which detonation is theoretically possible if you are running poor fuel).

Removing the air intake temp sensor effectively does the same thing (the Moronic doesn't receive a temp signal so it never knows whether there is high ambient air temps) -- however, it now also doesn't know whether the air is cold. Years ago, there was a debate as to whether that is a concern, for example, does the Moronic use the air temp sensor to determine whether the air is colder (and hence more dense, requiring extra fuel)? Once it became clear that the Moronic uses coolant temp to decide whether the engine is cold during/immediately after start-up, the questions were limited to the unknown of whether the air temp sensor is used for anything more than the detonation prevention function.

Bottom line, no one outside of BMW AG knows whether the air temp sensor is used for more than one purpose. Many reported no problems running with sensor disconnected, but personnaly, I couldn't believe the air temp sensor was present for only that reason, so I left it attached and removed the cat code plug on my '00 (at least until I received one of the first revised Moronics without the ignition retard "feature" and swapped it in). I'd suggest you do the same -- it's a bit of a hassle to remove/install the plug, but it's much more certain what the consequences of your actions are. FWIW, I doubt you'll ever want/need to put the plug back in. And it's less hassle to get to the plug than to the air temp sensor.

HTH,
 

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Thanks for the thorough reply Mark! :wave To continue this line of thinking of not being sure if the temp sensor is used only to detonation prevention: Wouldn't the switch in-line be an easy solution. When hesitation is experienced, just switch the temp sensor offline? Here in Finland too hot air temperature / weather seldom is the problem. :mad: So in those rare cases one could just switch that sensor off?

I do have quite a lot of electronics in the trunk and removing it is a hassle of its own. So (temporary) disabling the temperature sensor is just an easier option.

/Seppo
 

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Disconnecting the air temp sensor made a world of difference on my 99LT in hot weather. No more hesitation. I did that mod 3 years ago, I put a switch instead of just disconnecting the sensor so as I could put it back on and off thinking that it would be better to turn it back on in colder temperature for better MPG. However, I did not see any difference in fuel consumption so I have kept it off all time all year long since. Recently I turned it back on to test it and sure enough the hesitation at low RPM in hot weather was back.
 

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Alpac said:
Disconnecting the air temp sensor made a world of difference on my 99LT in hot weather. No more hesitation. I did that mod 3 years ago, I put a switch instead of just disconnecting the sensor so as I could put it back on and off thinking that it would be better to turn it back on in colder temperature for better MPG. However, I did not see any difference in fuel consumption so I have kept it off all time all year long since. Recently I turned it back on to test it and sure enough the hesitation at low RPM in hot weather was back.
Thanks for the confirmation. Time for TupperWare party again!

Seppo
 

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Mark, you are correct, IF the bike has the updated motronic in it. There was a service bulletin, and I have a copy of it somewhere but not sure I could find it now, that said you had to have the dealer read out the motronic information to be sure the newer one was installed. If not, the new one was supposed to be ordered by the dealer and installed BEFORE removing the CAT Code plug. Unfortunately, there was a severe shortage of the upgraded motronics, so later dealers discovered that removing the temp sensor would suffice, but not as good as the motronic with the secondary map that could be picked by removing the yellow cat code plug. In very late 2000 to early 2001, the cat code plug wiring was removed from the harness, and the brown wire loop was added. Removing the plug in the early ones did the same thing as cutting the wire loop later.

If you have the yellow cat code plug, you will not have the loop in the brown wire. If you have the brown wire loop, you should have the motronic with the secondary map that can be activated by cutting the wire. If you have the yellow cat code plug, you MAY have the correct motronic if your bike's manufacture date is late 2000, if '99 or early '00, probably not. (They started putting the newer motronics in before the harness change to remove the plug and add the loop was fully in effect). If not, pulling the cat code plug was NOT recommended, but pulling the wire from the temp sensor is the second best thing to do for the old motronic.

My '01, which had a late 2000 manufacture date still had the cat code plug, but also had the updated motronic, so the dealer pulled the cat code plug on it.

In any case, DO NOT pull the plug/cut the wire AND disconnect the temp sensor! Do only one. I still had a little hot hesitation on mine after the plug was removed, and disconnected the temp sensor for a little while, did not help. BUT I also think that this may have contributed to my later detonation damaged pistons!

mneblett said:
The Moronic doesn't do anything like set a code or required a "reset" in response to disconnecting or re-connecting the temp sensor (it's just an input that's either present or not) -- but I don't favor this method on a '99; IMO, it's better to remove the trunk and cover panel and remove the "cat code plug."

Removing the cat code plug tells the Moronic to use an alternate fuel injection/ignition map which does not have the ignition timing retarding in one specific condition -- a combination of high ambient air temperature, low rpm, and a relatively high throttle setting (corresponding to a significant load on the engine -- a condition in which detonation is theoretically possible if you are running poor fuel).

Removing the air intake temp sensor effectively does the same thing (the Moronic doesn't receive a temp signal so it never knows whether there is high ambient air temps) -- however, it now also doesn't know whether the air is cold. Years ago, there was a debate as to whether that is a concern, for example, does the Moronic use the air temp sensor to determine whether the air is colder (and hence more dense, requiring extra fuel)? Once it became clear that the Moronic uses coolant temp to decide whether the engine is cold during/immediately after start-up, the questions were limited to the unknown of whether the air temp sensor is used for anything more than the detonation prevention function.

Bottom line, no one outside of BMW AG knows whether the air temp sensor is used for more than one purpose. Many reported no problems running with sensor disconnected, but personnaly, I couldn't believe the air temp sensor was present for only that reason, so I left it attached and removed the cat code plug on my '00 (at least until I received one of the first revised Moronics without the ignition retard "feature" and swapped it in). I'd suggest you do the same -- it's a bit of a hassle to remove/install the plug, but it's much more certain what the consequences of your actions are. FWIW, I doubt you'll ever want/need to put the plug back in. And it's less hassle to get to the plug than to the air temp sensor.

HTH,
 

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dshealey said:
Mark, you are correct, IF the bike has the updated motronic in it.
Thanks, David! :thumb:

I'm getting long enough in the tooth that I'm beginning to forget these details -- I probably should stop posting on K12 stuff unless/until I get another one to refresh my memory!
 

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mneblett said:
Thanks, David! :thumb:

I'm getting long enough in the tooth that I'm beginning to forget these details -- I probably should stop posting on K12 stuff unless/until I get another one to refresh my memory!
At least you have a bike! I have not had one now since Nov. '04. :( Hard to believe it has been that long!

My knowledge of the Cat Code Plug/brown wire issue is due to much study of it when I had my '01 with the hesitation issue. I may have to try and find the service bulletin this weekend so I can post the information that was in it. If I remember correctly, that bulletin was posted on the old site, and BMW made us remove it. I should be able to post some of the pertinent information in it should I find it though. That bulletin is so old now, maybe posting it would not be a problem? Statute of limitations?
 

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dshealey said:
That bulletin is so old now, maybe posting it would not be a problem? Statute of limitations?
Alas, copyright is long-lived -- and the Mothership is not particularly flexible in this area. :(
 

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I performed the Cat Code plug removal as well as a Cannisterectomy after reading this thread.

I have a 2001 LT and was experiencing hesitation below 3000 RPM after the engine was running at temp and the outside temp was over 80 degrees.

The bike ran much better afterwards. No more hesitation and I've been running premium fuel and have not noticed any pinging.

Here are some pics I took during the process.
 

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midwestrider said:
I performed the Cat Code plug removal as well as a Cannisterectomy after reading this thread.

I have a 2001 LT and was experiencing hesitation below 3000 RPM after the engine was running at temp and the outside temp was over 80 degrees.

The bike ran much better afterwards. No more hesitation and I've been running premium fuel and have not noticed any pinging.

Here are some pics I took during the process.
Hi Troy, you are true.

My k1200LT was a little hesitation, one week ago here in east Spain with abt 40 degrees Celsius, i removed the yellow CCP and runs MORE better and smooth,,, surprising, the fuel consumption has lowered a little (im using 95 octanes).

I think that the words of mneblett are NEAR true ;) : "Removing the cat code plug tells the Moronic to use an alternate fuel injection/ignition map"

BUT in very early LT 1999 no updated motronic occurs that this only map can be modified with jumpers.

The 99' no updated, the (only one) injection map can be modified by jumpers: 30, 87, 87A, 85 and 86 with the common entry. Like R1150RT style but no necessary the same codes... :(

No jumpers = Default values in the injection map.

The two maps is a failed attempt to solve a problem in most cases :D

Too many variables and combinations that confusing the users :mad:

And too few information about CCP jumpers in k100LT.
 

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pepolis said:
Hi Troy, you are true.

My k1200LT was a little hesitation, one week ago here in east Spain with abt 40 degrees Celsius, i removed the yellow CCP and runs MORE better and smooth,,, surprising, the fuel consumption has lowered a little (im using 95 octanes).

I think that the words of mneblett are NEAR true ;) : "Removing the cat code plug tells the Moronic to use an alternate fuel injection/ignition map"

BUT in very early LT 1999 no updated motronic occurs that this only map can be modified with jumpers.

The 99' no updated, the (only one) injection map can be modified by jumpers: 30, 87, 87A, 85 and 86 with the common entry. Like R1150RT style but no necessary the same codes... :(

No jumpers = Default values in the injection map.

The two maps is a failed attempt to solve a problem in most cases :D

Too many variables and combinations that confusing the users :mad:

And too few information about CCP jumpers in k100LT.
K1200LT sorry.
 
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