Calibrate OBC on X3 to get correct mileage?

[nikasp]

Hi,

My On Board Computer gives me a very poor result. It usually shows 0.65 liters/10 kilometer (common way to display mileage in Europe) while the real value is 0.75. I.e. 13% off.

I have read in some forums that people have been fiddling with some constant in the OBC. Default setting was 1000 and could be adjusted up or down by 25%.

Is it possible to do this on my 2007 X3 by myself or in the shop?

[nikasp]

I found this about the On Board Computer but not clear how to get further. I read something somewhere where you could change the mileage in the following way: if you want to increase the mileage by 10% you set it to 900, decrease set to 1100. But can´t find the page again...


BMW X3 hidden OBC menu
--------------------------------------------------------------------------------
Did a simple search here and found it on our forum. I also remembered an E46 list and found it again, and it covers the E__ OBC.I am going out to play and see if I can get the rest to function!
THE LIST:
=========
Instructions to access the hidden OBC functions:
1. Hold Trip Reset while turning ignition key to on position
2. OBC should show "Test"
3. Use Trip Reset to select function 19.0 that unlocks all the features
3. Wait for display to show "Off"
4. Depress Trip Reset for 1/4 second and release it
5. With no delay press Trip Reset several times to select one of the following function s
==========================================

BMW E46 On-Board Computer (OBC) Hidden Codes
nr example description
1 Car Engine and cluster data
1.0 46nnn Chassis nr/VIN serial number (last 5 digits)
1.1 4nnn K-number
1.2 690236 Cluster Part #
1.3 045210 Coding (04)/diagnosis (52)/bus index (10)
1.4 1200 Week (12)/year of manufacture (2000)
1.5 09_160 Hardware (09) and software # (16.0) of cluster
1.6 Not used
1.7 04__44 CAN-version (04) KI-revision index (44)
2 (test) Cluster System Test - Activates the gauge drivers,
indicators and LEDs to confirm function
3 SI Data
3.0 1098 Used fuel in liters since last SI (Service Inspection)
3.1 0231 Periodic inspection days; elapsed days (since last SI)
4 Momentary Consumption
4.0 0145+ Instant fuel consumption - 0145=14.5 liters/100km
4.1 0018 Instant fuel consumption - 0018=1.8 l/Hour
5 Distance Gone Consumption
5.0 082 Average mileage; 082=8.2 liters/100km
5.1 0536 Calc. km to refuel (momentary distance to go)
6 Fuel Level sensor inputs in liters
6.0 109330+ Fuel level averaged; Left half sensor input=10.9 liters; Right sensor input=33.0 liters
6.1 0439+ Total tank level averaged; vlgs 6.0: 10.9+33.0=43.9 liters
6.2 0442+ Indicated value (44.2) and tank phase
7 Temperature and Speed
7.0 021+ Coolant/Engine temperature (2.1C)
7.1 130 Ambient/Outside temperature - chg met 5 pts. 125/130/135
7.2 + Engine speed / Current RPMs 1/min
7.3 + Vehicle speed / Current Speed in km/hour
8 Input value in HEX form
8.0 1d0+ System voltage ADC-Value Hex code
8.1 26C33C+ ADC Values HG left/HG right
8.2 0000 ADC Value brake degradation sensor (000=o.k.)
8.3 18C ADC Value outside temperature
9 Battery
9.0 140 Battery Voltage - 140 = UB 14.0v
9.1 242013+?
9.2 074_78+?
9.3 0011+?
10 Not used
11 Not used
12 Not used
13 GonG Gong Test
14 Not used
15 Status cluster I/O-ports (bit codes) 0=low; 1=high
1st-belt contact, seat belt fastened=0; 2) ignition lock contact, key inserted=0; 3) door contact, door open=0; 4) clock button pressed=0; 5) SI reset=0, for reset=0; 6) EGS transmission failure=0
Status Digital Outputs (bits) 0=inactive, 1=active
1) Gong output; 2) Brake warning lamp; 3) Low fuel warning lamp; 4) EGA lamp; 5) seat belt lamp; 6) manipulation dot
16 Not used
17 Not used
18 Not used
19 Lock Status; unlocks functions in range 3-18
19.0 L-On/L-Off Unlock: press button when "L-Off"
20 Not used
21 Software Reset; reset OBC settings
00 End of test

[JCL]

Do you have a performance chip installed? Any other engine modifications? Not a common issue to have the fuel consumption reading so far out.

[nikasp]

Nope, the car is extremely stock. Old company lease car so I got after the previous owner had it for three years. Even if it had a chip I would be able to adjust the mileage - if/when I find out how

I can check and test most stuff in the list above but cannot change KVBR value.

Edit:
I have read more on this and for E46 cars it is value/key 20 that holds a KVBR (fuel coefficient) value that can be in the range 750 to 1250. E.g. if I want to adjust the MPG up I take:

Current value x (real MPG/OBC readout MPG). E.g. if current is 1000 my new value would be 1154.