2010 RT fuel gauge and onboard computer questions

[Robus]

Hi all. I'm finding the fuel gauge on the RT inaccurate. What I'm seeing on the readout bears little resemblance to what I find when gas up. According to the gauge and the low fuel caution light, I should have been running on fumes when I pulled into a gas station this afternoon. In fact there was well over a gallon left in the tank. Maybe I'm not understanding how it factors in the reserve.

 

Second question: Can anyone say how the onboard computer tracks gas mileage? According to the computer, I'm getting 42-45 mpg. When I calculated my last tank myself, it was closer to 38 mpg (that sounds poor, but I'm still running the engine in--varying RPM a lot). I guess what I'm asking is this: over what interval does it base the calculation. Fuel burn at this moment in time? Average since the last fill-up? Average on the current ride? Running average over several rides?

 

The reason I'm interested to know is that the readout for endurance on remaining fuel seems to be based on the mpg estimate (and the inaccurate fuel gauge). I notice that if I ride at lower RPM for a while, the estimated endurance will increase. On a tank of gas, I get nowhere close to what it estimates. Typically, after a refueling, it estimates that I can go 310 miles. Invariably I trip the low fuel indicator at about 220-240.

 

Thanks.

[Tony_K]

Welcome to your new BMW and its overly complicated components!

Enjoy this thread HERE. Time to schedule a appointment with your dealer. They are probably already waiting for you.

[Robus]

Thanks Tony. I saw that thread but assumed it was about a different issue. They're talking about failure of the fuel sensor rather than it just plain not being worth a rodent's tush.

 

What happens when these sensors fail? Does the display stop displaying? Or do you start seeing inaccurate readings?

[dirtrider]

Morning Robus

 

The gas gauge should be somewhat accurate. The original factory fuel strips seemed to be the most accurate. The original replacements were pretty decent also. The later fuel strip replacement procedure simplified the calibration process so the reserve was a bit less accurate on replaced fuel strips.

 

 

I really don’t have any background on the 2010 RT fuel gauge accuracy or reserve size. It should all be in your riders manual. If you don’t trust it take a gallon of gasoline with you and run your bike to the yellow reserve light, write that down, then run it until it starts to sputter and write that down. Then see how that stacks up against your riders manual info.

 

On the on-board computer’s figuring of the fuel mileage? That is somewhat complicated but basically it knows how long the fuel injectors are triggered on, at what injector voltage, and at what fuel pump speed. It also knows how far the bike has gone. It uses the above to do an average of fuel consumption. Then on the miles to empty it uses the average fuel consumption and fuel strip reading to try and guess how many miles you can go till empty.

 

One thing that can confuse the system is if you don’t clear the average MPG at fill up time and clear MPH average at fill up. Not always but it sometime helps.