Adjusting the BC's MPG reading

[12R12RT]

I've searched for this, and tried the LT method on my RT to no avail.

 

Does anyone know how to get into the BC and adjust the MPG reading on an RT?

 

I've tracked my actual MPG vs what the BC says and it is off my an average of 43.1(actual) vs 46.2(BC).

 

Oh, the agony of OCD...

 

Thanks,

 

Tom

[dirtrider]

Afternoon Tom

 

Basically not doable.

 

Your BC uses a pretty extensive algorithm using injector on time, battery voltage, engine RPM's, fuel pump voltage, miles traveled, etc to figure MPG.

 

If you haven't been --definitely re-zero your travel computer & fuel mileage miles traveled at each gas stop as that limits the fuel BC mileage to just since last re-zero.

 

If it is still way off maybe you have a fuel injector that is flowing incorrectly per pulse cycle or something else wrong with your fueling system.

 

Anything aftermarket like a Techlusion or other fuel controller can add fuel to the engine that the BC doesn't know about.

 

If it is still under warranty see if your dealer will address your problem with new fuel injectors or a new computer. Maybe a service bulletin on that issue?

 

[12R12RT]

OK, I thought as much and thanks for confirming. A fairly common algorithm in OEM trip computers.

 

I was hopeful that this procedure for the K-bikes would have carried over, where that algorithm apparently has a correction factor:

 

"To adjust the MPG readout on the BC, do the following:

1) Divide the displayed MPG value by the actual MPG value, than multiply by 1000. For example, 48 MPG divided by 55 MPG = 0.872 x 1000 = 872. Remember this number. (Editor's note: You might want to run a few tanks through resetting the BC only on the first tank but measuring actual MPG by hand for each tank to get a good average.)

2) Press the reset and mode buttons on the BC simultaneously, then release. (Editor's note: do this with the ignition ON.) The BC will display '01'.

3) Use the BC button on the right hand control switch to scroll through the four test screens. Stop when '03' is displayed and then press the reset button. WARNING: Watch the screen carefully at this point! As soon as you press 'reset', look for the very first number displayed. This is the current MPG calibration factor but it's only displayed for a second before the number starts to count up. The OEM setting is usually 1000 (no calibration) but it might not be and you may wish to return to the original number if you're not happy with the results of this exercise. The number will begin to scroll, starting with the current setting, up to 1250. It will then begin again at 750 and continue up. When this number reaches the number closest to the number that you remembered from step 1), press the reset button again. That will reset the calibration factor for your display."

 

That was found on BMWLT...

 

Tom

 

 

 

[6speedTi]

I have a BMW 318ti with the mini version of the full size computer.

BMW presets the numbers in the computer. I was always reading higher than actual on my MPG. I could not find any info in the BMW service manual or troubleshooting manual. One day someone with some insight found a way to adjust the base numbers to correct the MPG readings. I made the adjustments and I got it right on. My point is BMW uses same technology on most of their products and on my car I was able to correct the MPG readings but no info was published to the consumer. So maybe there is a way to do it but someone needs to get more detailed info from BMW who is in the know. This is no different than adjusting the MAP curve on a computer as long as you have access to do it. It is a matter of changing the base reference number. Figuring out how to do it? Well that is the next challenge.

[TestPilot]

I had a ti also and made the same correction. Maybe BMW's engineers now feel their system is perfect and needs no correction.