Suddenly 10 mpg less

[xoomerite]

2006 R1200RT. 78,000 mi. I got it at 67,000 miles. Dealer maintained previously. I have done the rest. New fuel pump at 68,000 miles.

 

In the past few tanks of fuel, my mileage has suddenly dropped from an average of 51 mpg to 41 mpg over 1000 miles.

 

I have been riding a lot of interstate briskly. Recent trip to Alabama, the traffic was cruising at 85 mph. The only change that I have made to the operation of the bike was to change the alternator belt and air filter, prior to noticing this change. It is time for service (12,000 mile service).

 

All this time I have been running my driving lights, heated grips, and heated gloves and jacket. Riding solo as usual with the stock screen fully up in the cold weather.

 

I have been using real gasoline and ethanol-diluted randomly throughout this time.

 

What should I be looking for?

 

Chris

[Downs]

Winter formulations of gasoline can cause a drop in fuel mileage.

 

The windscreen being in the full up position can cause a good drop in mileage. I see a 5+ MPG drop when running my Madstad in a high position.

 

Your 85mph cruise isn't helping much either.

[malcolmblalock]

Cold oil takes more energy to move it through the engine. Also, more current draw takes more energy.

 

Mine does about the same way--not quite so drastic, but often down in the low 40s in the winter compared to around 50 in summer.

[Bots]

Mine seems to average 42+ mpg overall all the time. thats since new. And thats not hot rod'n. (28000 mi) 2006 RT

 

[CoarsegoldKid]

I would not worry about it. Like others mentioned, winter blend, windscreen up, and 85 mph will drop the fuel economy. So will luggage hanging off the side and backend cause a change.

[Devil Duc]

My mpg's dropped about the same here in WI in Nov on a new to me 2007 RT. I was disturbed at first and then forum searches and the guys on this board, the dealer, and some other gear heads showed me the light. Winter blend fuel, shields up, luggage, speed, cold oil, can all drop mpg. I am waiting to see what happens in spring before I blow any figurative head gaskets. Meanwhile: enjoy riding down there. I got about 3 inches of ice on my street!

[hopz]

I know this may not be directly linked to your question but to be on the safe side... are you re-setting the MPG calculator at every tank-up? or doing the math your self?

 

 

[Deek]

I know this may not be directly linked to your question but to be on the safe side... are you re-setting the MPG calculator at every tank-up? or doing the math your self?

 

 

Yeah, that got me once also! I never used to reset things, didn't really know it'd make such a difference. I hope the OP's problem turns out to be so simple, but with the experience he has on his bike I doubt it. I drop about 3-5 mpg if I'm really fast, like across OK, or if I'm constantly in traffic (rare). My mileage does drop just a bit in the winter - I think about 5 mpg but not sure.

 

[Gene#3]

I had the same thing occur last winter. From 50+ a gallon... to 40 or less, measured the old fashioned way! Six months or so later my mileage returned. I finally realized, when I had brought my bike to the dealer to delete fault codes re: my ESA, he had also deleted another code... I don't recall exactly what it was, but something related to air/fuel or temp sensor. I'm pretty sure this was the culprit. No way to tell other than a GS911 or trip to a BMW dealer...

[Deek]

From 50+ a gallon... to 40 or less, measured the old fashioned way!...

 

I'm always surprised when the USA MPG I calculate using the old way is actually higher than what the bike's computer calculates, at least for the 3-5 tanks I've hand calculated....usually quite a bit, about 3-5 mpg is what my records show.

[tallman]

Are you using odometer or GPS for mileage total?

 

Perhaps the 1200's are more accurate than previous models.

[xoomerite]

I don't have a MPG calculator on this bike. I just try to fill the tank the same each time and calculate from there. I usually fill up as soon as the fuel pump icon lights up. The gauge generally shows 1/8 tank at that point.

 

I forgot about winter fuel blends. If I had thought about posting the cruising speed experience and having the shield all the way up, it should have been apparent. It certainly was strange to have the traffic running that fast on that trip down and back.

 

Thanks for all the pointers.

 

Now back to our regularly scheduled program.

 

Chris

[roger 04 rt]

One last thought, in addition to winter blends, and at 60-80 MPH the difference in aerodynamic drag between 80F and 20F is 13%. That factor alone would drop your mileage from 50 mpg to 43/44 mpg.