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Discussion Starter #1
My 2002 LT seems to be getting 125-145 on ~5.3 gallons (~25 mpg in city riding. I commute 1 up around 13 miles each way (25-28 miles per day) with speeds ranging 30-60 mph. I fill up on the side stand to the bottom of the filler and have ran it until the light comes on. I've tried keeping the rpms low (<5.5k) and tried >5.5k with no real difference. I've replaced the O2 sensor, fuel filter and lines, spark plugs, cut the brown wire reset the TPS and run premium fuel. It idles and rides smooth with no noticeable operating issues just low fuel economy. The plugs had a nice tan color, no fuel smell from leaks or rich condition. What else could cause the mpg to be so low?

I need to run a few more tanks to get a more accurate number since the fuel lines have been replaced and possibly reset the TPS again. I also need to run a few tanks at highway speed to see the difference there. I'm just looking for other items I may be missing.
 

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Calculate your normal highway cruising mileage. If low, when cruising for extended distances, then look for issues. General mileage is going to depend somewhat on riding style, roads etc so the best gauge is highway. If you are severely low there then start looking for problems.

Brown wire cut? Who did it and why? Was there any difference prior to the brown wire being cut as in, did it solve the issue or did mileage drop after?

You may have to get hold of a GS911 and engage Sailor to diagnose this if you are low on highway. The Temp sensor may be off a little and it would use more fuel. Plugs are normal color so not too rich but maybe a little.

What are you using to reset the TPS? Are you doing the ignition and throttle thing? you are Not physically adjusting it i would expect.
 

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Discussion Starter #3
Calculate your normal highway cruising mileage. If low, when cruising for extended distances, then look for issues. General mileage is going to depend somewhat on riding style, roads etc so the best gauge is highway. If you are severely low there then start looking for problems.

Brown wire cut? Who did it and why? Was there any difference prior to the brown wire being cut as in, did it solve the issue or did mileage drop after?

You may have to get hold of a GS911 and engage Sailor to diagnose this if you are low on highway. The Temp sensor may be off a little and it would use more fuel. Plugs are normal color so not too rich but maybe a little.

What are you using to reset the TPS? Are you doing the ignition and throttle thing? you are Not physically adjusting it i would expect.
I've been off the bike for a few weeks so I haven't had a chance to get some good highway runs to determine my mileage. That's my next step since city riding can sway the numbers considerably.

I cut the brown wire a few months ago when I noticed poor mpg and hesitation at take off. The symptoms came at the same time as the >80°F days. It helped the hesitation a little bit but it returned and that's when I found the internal fuel line was cracked. I replaced the fuel lines and have ran just under a tank through it since. I'm sitting at 100 miles and approximately a 1/4 tank left. All of the hesitation is gone, I could reconnect it and see if there is a difference.

I did the disconnect the battery for ~30 minutes, turn on the ignition, throttle twist x3, ignition off, ignition on and ride. I did that when I changed the O2 sensor and it seemed to increase the mpg but not by much. I may need to do it again and then take a good run on some back roads.
 

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I've been off the bike for a few weeks so I haven't had a chance to get some good highway runs to determine my mileage. That's my next step since city riding can sway the numbers considerably.

I cut the brown wire a few months ago when I noticed poor mpg and hesitation at take off. The symptoms came at the same time as the >80°F days. It helped the hesitation a little bit but it returned and that's when I found the internal fuel line was cracked. I replaced the fuel lines and have ran just under a tank through it since. I'm sitting at 100 miles and approximately a 1/4 tank left. All of the hesitation is gone, I could reconnect it and see if there is a difference.

I did the disconnect the battery for ~30 minutes, turn on the ignition, throttle twist x3, ignition off, ignition on and ride. I did that when I changed the O2 sensor and it seemed to increase the mpg but not by much. I may need to do it again and then take a good run on some back roads.
Since you found a different cause in the internal fuel line, at least for the time being, I would reconnect the brown wire and start there since the brown wire cut does install an alternate fuel map. The secondary map may have temporarily masked the fuel line issue. If it ran fine in previous years at over >80°F then lets take it back to stock and look at how it does there. You can always cut it again. :) Not all bikes need the brown wire solution.

My favorite injector/fuel system cleaner is Techron, arguably one of the better ones out there and that would be something to try short of removal/clean and calibration if restoring the brown wire does not help with the mileage.

After that, it is GS911 time to see what is going on with the motronic. Let us know when you get some highway mileage on her and what the result is.
 

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check and or change o2 sensor if mileage seems that low, combined driving on my 2000 lt never seems to be below 35 mpg

usually in the 40's
 

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Discussion Starter #6
Since you found a different cause in the internal fuel line, at least for the time being, I would reconnect the brown wire and start there since the brown wire cut does install an alternate fuel map. The secondary map may have temporarily masked the fuel line issue. If it ran fine in previous years at over >80°F then lets take it back to stock and look at how it does there. You can always cut it again. :) Not all bikes need the brown wire solution.

My favorite injector/fuel system cleaner is Techron, arguably one of the better ones out there and that would be something to try short of removal/clean and calibration if restoring the brown wire does not help with the mileage.

After that, it is GS911 time to see what is going on with the motronic. Let us know when you get some highway mileage on her and what the result is.
I just bought the bike a few months ago with 37,000 miles on it so it spent a fair amount of time sitting. I think the injector cleaner is definitely in order. I'll pick it up and run it through the next few tanks. When I got the bike the temps were below 80° and it seemed to run fine at that time. About a week after getting it the temps hit over 80 and the hesitation started. The brown wire helped some but it may have been covering the beginning of the hose failure like you said. I figured with the temps here being 90-100 every day it wouldn't hurt to leave the wire cut but returning to stock makes sense.
Would there be a need to rest the motronic TPS when changing maps or when there is a change in the fuel system? If I had a hole in my fuel line when I did the last TPS reset if that could be causing an issue now that I have a intact system. I don't know how much pressure was being lost or how much that makes a difference with the TPS.
 

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Discussion Starter #7
check and or change o2 sensor if mileage seems that low, combined driving on my 2000 lt never seems to be below 35 mpg

usually in the 40's
That was my initial diagnosis from reading here. I installed a new O2 sensor and it seemed to bump it from ~25 to ~35 mpg but then I found the hole in the fuel line. I replaced the fuel lines and the mpg appears to be around the ~25 mpg still. I would expect a mid to high 30's for city and 40's for highway from what the general consensus is.
 

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I just bought the bike a few months ago with 37,000 miles on it so it spent a fair amount of time sitting. I think the injector cleaner is definitely in order. I'll pick it up and run it through the next few tanks. When I got the bike the temps were below 80° and it seemed to run fine at that time. About a week after getting it the temps hit over 80 and the hesitation started. The brown wire helped some but it may have been covering the beginning of the hose failure like you said. I figured with the temps here being 90-100 every day it wouldn't hurt to leave the wire cut but returning to stock makes sense.
Would there be a need to rest the motronic TPS when changing maps or when there is a change in the fuel system? If I had a hole in my fuel line when I did the last TPS reset if that could be causing an issue now that I have a intact system. I don't know how much pressure was being lost or how much that makes a difference with the TPS.
It couldn't hurt to do the reset. I don't know if switching to a different map resets that data in the motronic or not. If it had trouble idling, then i would certainly do the procedure after reconnecting.
 

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You might consider a switch for the brown wire so you have the best of both worlds. Is the temp. sensor in the airbox connected? Should only do one at a time. Should run Premium fuel.

About the only thing consistent with poor fuel milage is a bad o2 sensor, I know you replaced it, but that’s about it. I would concentrate in that area - disconnected wires or just a bad sensor.

I see no rhyme or reason why fixing a split line in the fuel tank would increase/decrease your milage, the engine would run poorly but wouldn’t use extra fuel.
 

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I installed a new O2 sensor and it seemed to bump it from ~25 to ~35 mpg but then I found the hole in the fuel line. I replaced the fuel lines and the mpg appears to be around the ~25 mpg still.
Where did you get the fuel line? If you got the correct stuff it would have been OVER PRICED... I am wondering if you have a low fuel flow. To much air, not enough fuel... 911 time.
 

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Where did you get the fuel line? If you got the correct stuff it would have been OVER PRICED... I am wondering if you have a low fuel flow. To much air, not enough fuel... 911 time.
He got submersible line, I remember the thread. I suggested the nylon lines from BBY but he had already used the proper rubber lines as he didn't have the time to wait on ordering it.
 

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Discussion Starter #12
You might consider a switch for the brown wire so you have the best of both worlds. Is the temp. sensor in the airbox connected? Should only do one at a time. Should run Premium fuel.

About the only thing consistent with poor fuel milage is a bad o2 sensor, I know you replaced it, but that’s about it. I would concentrate in that area - disconnected wires or just a bad sensor.

I see no rhyme or reason why fixing a split line in the fuel tank would increase/decrease your milage, the engine would run poorly but wouldn’t use extra fuel.
I reconnected the wire with a bullet connector for now. I can disconnect and reconnect as needed and change to a switch later if needed. I'm pretty sure the temp sensor is still connected since I've never disconnected it. I'll double check it just to make sure. I've been running premium fuel so that shouldn't be an issue.

I replaced the O2 sensor with a new one thinking that was the problem. If I can't find any other solution I can return it for a new one and see if that changes anything. I checked it prior to installation for reactivity and it was working so I'm doubtful that's the issue. I will double check the connection to make sure that's not an issue.

To my understanding if you have a clogged injector or low fuel pressure to the injector the cylinder doesn't get as much fuel as it should. This lean condition is read by the O2 sensor which then tells the injectors to be "on" longer to richen the combustion mixture. I'm not 100% clear on why it would cause an increase in fuel consumption. My thought is you'd still use the same amount of fuel but injected over a longer time period and most likely develop running issues (misfire, low power, etc.).
 

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Discussion Starter #13
Where did you get the fuel line? If you got the correct stuff it would have been OVER PRICED... I am wondering if you have a low fuel flow. To much air, not enough fuel... 911 time.
I picked up the submersible lines from the dealer and the external hoses I picked up at the auto parts store. The stock parts were over priced at $60 for the two parts, next time I'll buy it from BBY. The external is 5/16 SAE 30R10 left long enough not to crimp themselves. I'm leaning toward dirty injectors at the moment. If it sat as much as I believe it did then it makes sense the old fuel and deteriorating fuel line could of sent junk to the injectors. I'll try the injector cleaner and see if that helps. If not then I'll have to find someone with a 911 to help me. My local dealer doesn't think they have the software to talk to my bike anymore. :frown:
 

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Discussion Starter #14
He got submersible line, I remember the thread. I suggested the nylon lines from BBY but he had already used the proper rubber lines as he didn't have the time to wait on ordering it.
Yes, that's correct. Turns out as long as it took the dealer I probably could of ordered it from BBY. Oh well, at least I learned how to change it without pulling the tank. lol

I reconnected the brown wire and noticed a little bit of hesitation this morning but it could of been in my head. It was just under 80 when I rode in so this afternoon will tell me if there is a difference.
 

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Here is a place to send your injectors if you want. I'm going to do my K bike this winter:
Mr Injector - Home
 

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Where is the plug that you use for GS911. I don't remember seeing a plug for it. Thanks Jim
On my 2001 it is under the seat on the right side behind the battery in a clip with a grey cap on it near the brake reservoir. May vary on different models with different ABS.
 

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On my 2001 it is under the seat on the right side behind the battery in a clip with a grey cap on it near the brake reservoir. May vary on different models with different ABS.
Same on my 2007.
 

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Discussion Starter #19
With the brown wire reconnected and 100°F I did notice a slight hesitation on takeoff on the way home. It wasn't as responsive on takeoff but once I was moving and >2.5k RPM it seemed to act as normal. I filled the tank and added Techron injector cleaner to see if that helps. I reset the motronic with the rest button just to see what the initial reading looked like. It is showing right around 30 mpg for what it's worth. When I filled us and calculated the mpg it came out to ~30 mpg. I'll take some long runs on the interstate this weekend and get some better numbers.

I did notice it got hotter then it has been but that could of been due to the 100°F temp, high humidity, stop and go traffic and running in lower gears. Both fans were working and there was plenty of coolant but it did get hot enough at one point for the light to come on. If it happens again I'll double check to make sure I don't have air in the system and order a new radiator cap since this one is probably the original.
 

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Correct me if I am wrong no where where do I see that you are actually manually calculating the mileage. If you are using the gauge, not accurate. If you are reading the little sensor screen on the bike all it is is an algorithm to do a rough calculation. If you really want the number then ride a tank full of gas, fill up and divide into the miles.
 
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