BMW Luxury Touring Community banner

1 - 7 of 7 Posts

·
Registered
Joined
·
1,534 Posts
Discussion Starter #1 (Edited)
Hello again distinguished members. Well as many of you may know. I had a idle issue after a battery change out. Would not do a TPS reset. I installed a new O2 sensor. Still no results So she went to the local BMW dealer. He reset the TVA. Now she runs great. I also just installed a set of Avon 3DXM Storm 3's . Great tire Wow.. Sticky. Only thing I noticed was me and my wife were out yesterday. And in the middle of a left turn,I hit a tar snake. It unsettled the LT just enough,You know.. To make your butt pucker. Well. It was 93° out under a hot sun and probably softened the tar. So I'm not reading to much into that now. Anyway. Give them 2 thumbs up so far.I do now notice after the O2-sensor replacement. I do not get anymore black soot on my muffler. And no more of the occasional smoke on startup. Have noticed the mpg is slow to recover.It's creeping up slowly yesterday after a fill up. It rose to 34.5 from 31-32.5. May need to reset BC computer. But I have a zumo 550. I can track mileage with that. Will see if mpg improves.
 

·
Registered
Joined
·
165 Posts
+1 on the AVON's. Just put new set on my '01.

Hello again distinguished members. Well as many of you may know. I had a idle issue after a battery change out. Would not do a TPS reset. I installed a new O2 sensor. Still no results So she went to the local BMW dealer. He reset the TVA. Now she runs great. I also just installed a set of Avon 3DXM Storm 3's . Great tire Wow.. Sticky. Only thing I noticed was me and my wife were out yesterday. And in the middle of a left turn,I hit a tar snake. It unsettled the LT just enough,You know.. To make your butt pucker. Well. It was 93° out under a hot sun and probably softened the tar. So I'm not reading to much into that now. Anyway. Give them 2 thumbs up so far.I do now notice after the O2-sensor replacement. I do not get anymore black soot on my muffler. And no more of the occasional smoke on startup. Have noticed the mpg is slow to recover.It's creeping up slowly yesterday after a fill up. It rose to 34.5 from 31-32.5. May need to reset BC computer. But I have a zumo 550. I can track mileage with that. Will see if mpg improves.
 

·
Wrencher Extraordinaire
2005 K1200LT
Joined
·
14,167 Posts
Just do a reset on the BC you will have a good average in a single day of riding. When I take a long trip and pull the Bushtec I do a reset every day as it helps make the Mile to Empty more accurate.
 

·
Premium Member
Joined
·
7,612 Posts
Just do a reset on the BC you will have a good average in a single day of riding. When I take a long trip and pull the Bushtec I do a reset every day as it helps make the Mile to Empty more accurate.
How does a reset help the DTE? Is this only on the older models before the LCD dash?

My DTE appears to use real-time MPG as I can watch the DTE decrease as I climb a long hill and increase as I descend the other side. It would be nuts to us an average MPG value in a DTE calculation.
 

·
Wrencher Extraordinaire
2005 K1200LT
Joined
·
14,167 Posts
True, but it is part of the algorithm that computes DTE along with other inputs. I have no data but I suspect that it also uses injector pulse width as that would explain "making" gas going down hill. I have observed that the low fuel light (normally set to come on at 1 gallon left) will come on at different DTE based on the current MPG. If my average is 44 MPG the light comes on at 44 DTE, if I reset and the average for the day is now 35 MPG the light comes on at 35 DTE.

I discovered this the hard way on my first trip with a trailer. My MPG had dropped but the long term average was high (no recent reset). After the light came on I watched the DTE dropping and shortly after it went to 15 then -- I ran out of gas. So based on this I usually do a reset each day of a long trip as time in the mountains I get 48 - 50 MPG and trying to beat a head wind while maintaining 75 MPH is west Texas I get 28 MPG at best.

I doubt we will ever really know what all goes into computing DTE, but a reset is always in my hip pocket on long trips.
 

·
Premium Member
Joined
·
7,612 Posts
True, but it is part of the algorithm that computes DTE along with other inputs. I have no data but I suspect that it also uses injector pulse width as that would explain "making" gas going down hill. I have observed that the low fuel light (normally set to come on at 1 gallon left) will come on at different DTE based on the current MPG. If my average is 44 MPG the light comes on at 44 DTE, if I reset and the average for the day is now 35 MPG the light comes on at 35 DTE.

I discovered this the hard way on my first trip with a trailer. My MPG had dropped but the long term average was high (no recent reset). After the light came on I watched the DTE dropping and shortly after it went to 15 then -- I ran out of gas. So based on this I usually do a reset each day of a long trip as time in the mountains I get 48 - 50 MPG and trying to beat a head wind while maintaining 75 MPH is west Texas I get 28 MPG at best.

I doubt we will ever really know what all goes into computing DTE, but a reset is always in my hip pocket on long trips.
I am not familiar with the BMW algorithm, but most modern cars measure MPG by integrating the fuel injection pulses to measure fuel flow. With precise metering devices like fuel injectors this is far more accurate than the fuel tank level sensor. It certainly seems likely that the LT would use this approach also.

It seems unlikely to me that the DTE would be based on a long-term average when the real-time value is available and more relevant. I wonder if you have the correlation correct, but maybe the causation reversed. The real-time MPG is likely short-term averaged, probably using a "box car" average or something similar. I can guess this based on the lag in DTE update when in hilly terrain such as where I live.

It may be that the DTE is computed from the real-time average and by resetting the "long term" average each day you are keeping it close to the real-time average. This is pure speculation on my part, based solely on how I would do this if I was the engineer in charge. It is just more logical to me than using the longer term average maintained by the BC for display to the rider.
:smile:
 

·
Registered
Joined
·
1,534 Posts
Discussion Starter #7
Reset the MPG only? I was talking about a hard reset on the BC. There is a procedure here somewhere. Although. I see it increase/decrease as I'm rolling. I think it isn't necessary.
 
1 - 7 of 7 Posts
Top