Air Temp, Canistorectomy, Yellow Plug

[Jabrown]

I have a 99 LT with 72000 miles

About a month ago I searched the hall of wisdom and asked questions about the air temp sensor. I unplugged it, and it fixed my problem.

I pulled the topcase and to my surprise the PO did not remove the canister. So today I am removing the canister. Also While I was in there I found that little yellow plug that is also mentioned in the Hall of Wisdom.

Question is Do I have the moronic with 2 maps since there is a little yellow plug? If so can I leave the air temp sensor undone and unplug the yellow plug?

And my last question is Do I only have to remove the canister and plug the 2 lines?

I will eventually remove all the hose later when I pull the tank for something else. I know I will end up in there sometime this year I just don't know when.

[Chockkicker]

I have a 99 LT with 72000 miles

About a month ago I searched the hall of wisdom and asked questions about the air temp sensor. I unplugged it, and it fixed my problem.

I pulled the topcase and to my surprise the PO did not remove the canister. So today I am removing the canister. Also While I was in there I found that little yellow plug that is also mentioned in the Hall of Wisdom.

Question is Do I have the moronic with 2 maps since there is a little yellow plug? If so can I leave the air temp sensor undone and unplug the yellow plug?

And my last question is Do I only have to remove the canister and plug the 2 lines?

I will eventually remove all the hose later when I pull the tank for something else. I know I will end up in there sometime this year I just don't know when.
I think you have to leave the yellow plug in place. Do not plug the hose that runs to front right side of the bike from cannister , reroute it so the open end is close to bottom side of bike. Plug (a good plug) the cannister end of hose that runs up the left side of bike. Left hose is vacuume hose from carbs, right hose is vapor hose from fuel tank.

[Jabrown]

I just took it out for a test drive with the yellow plug undone and well it seems to run about the same. Accelerates just as quick and a quick reset of the mpg showed about the same as it was when it was plugged in. I calibrated the mpg last year and its usually within about 1 mpg of actual. It showed about 56 mpg doing 55mph (corrected error in speedo).

Thanks for the info on which line to leave open for the gas tank vent(I am assuming thats what it is).

So does anyone else have thoughts about the yellow plug and what its effects are, if the air temp sensor is undone as well.

[grifscoots]

I'd leave the plug in. I pulled mine on my 2000 on top of the air temp sensor, but Dave Shealey recommended putting it back in. So I did. One of the few times I did what I was told.

[zippy_gg]

On my 99 I did remove the yellow cat plug AND disconnected the air temp sensor at the airbox. I strictly used high octane gasoline and never had any issues. I was happy to have gotten rid of the hot temp hesitation, and that is a good thing because it is usually hot in the Los Angeles area, and I do ride in town a lot.:thumb:

PS. I often don't do what I am told!:rolleyes: :D

[dshealey]

I just took it out for a test drive with the yellow plug undone and well it seems to run about the same. Accelerates just as quick and a quick reset of the mpg showed about the same as it was when it was plugged in. I calibrated the mpg last year and its usually within about 1 mpg of actual. It showed about 56 mpg doing 55mph (corrected error in speedo).

Thanks for the info on which line to leave open for the gas tank vent(I am assuming thats what it is).

So does anyone else have thoughts about the yellow plug and what its effects are, if the air temp sensor is undone as well.

On a '99, unless the Motronic was changed out by a previous owner per the service bulletin, DO NOT remove the yellow plug! That will not work for a single map Motronic. It can cause real problems if done. You can have a dealer check the Motronic version to see if a previous owner had it changed out, but many were not aware of it and didn't when it was offered by BMW as a free change. That is no longer offered free for the old bikes that I am aware of, but you could try IF you are having hot hesitation and the dealer can verify it. Plug the air box temp sensor back in before taking it to a dealer to check it though!

[Jabrown]

what exactly will go wrong if it is undone. The bike still runs the same. Not trying to be arrogant I just want to justify pulling everything back off ....since I already put it back together.

I don't do as told.:D

[grifscoots]

what exactly will go wrong ....since I already put it back together. I don't do as told.:DIIRC, it puts the moronic into a default "limp home" mode. Very rich, which could cause a melt down to the cat, amongst other thangs.

[johnrehder]

I also remember that riding without the yellow dohickey for long periods screws up the top of your pistons and valve seats because of the rich fuel condition. Maybe David can chime in on this thought too.



IIRC, it puts the moronic into a default "limp home" mode. Very rich, which could cause a melt down to the cat, amongst other thangs.

[Jabrown]

fair enough, yellow plug is going back in. I just needed BS to motivate me to take it back apart. Its raining here anyway. I originally was just going to check if the canister was still in there. It was so I took it out.

[zippy_gg]

I also remember that riding without the yellow dohickey for long periods screws up the top of your pistons and valve seats because of the rich fuel condition. Maybe David can chime in on this thought too.I rode without the yellow plug for 2 years without any problem. I just made sure to fill up with high octane. Then my 99 was sold and moved to Tucson, AZ where it is even hotter, and the new owner is still very happy with the bike.