Why is the fuel consumption in the onboard computer always wrong?

FnoFFen · 07-12-2013, 07:54 AM

Again. My new 2011 525d got it wrong again. My onboard computer tells me my average fuel consumption for small distances is 8.0 liter per 100 km (29.5 mpg). When I check, however, it is 8.7 liter per 100 km (27 mpg).

This has been like this in all my three BMWs. The computer always shows less consumption than real. Since it seems like a systematic error what should be the problem getting it right?

Mr. Grumpy · 07-12-2013, 08:21 AM

You can adjust this in the hidden menu of your instrument cluster. Mine was almost 1.2 Gal. off and after tweaking the values in the menu is on the spot now.

dbs600 · 07-12-2013, 10:29 AM

Do you have a link to instructions on how to adjust this? Thanks!

Mr. Grumpy · 07-12-2013, 10:36 AM

1. Hold down the odometer reset button and turn the ignition on by pushing start/stop button.

2. Release the odometer reset button, and you should see a menu of 4 items on the dashboard. From here on, use the odometer-reset button to advance to the next entry through a short press, and to select through a long press.

3. Choose the one that says Unlock through the above, which will take you to a passkey screen. Your passkey is the sum of the last 5 digits of your VIN. Increment the two-digit number until you get to it, and with the long press of the odometer button, select it.

4.Then scroll down to correction factor and modify it from 1000 to whatever you require.

If your trip computer reads higher than true figures worked out, make the correction over 1,000. If your trip under reads, make the correction number under 1,000.

Copied from Chuck W. post.

FnoFFen · 07-12-2013, 11:21 AM

What is a odometer?

HighlandPete · 07-12-2013, 12:16 PM

My BMW's OBC have always been very accurate against brim to brim checks.

The E91 330d changed after a software update, went to reading about 10% lower than actual, had been less than 1% difference from new, reading on the optimistic side.

Current F11 is within 0.5mpg (imperial gallons) around the 30mpg range, again OBC reads on the optimistic side.

But we do have to allow for other build and running tolerances. One trip I make is about 90 miles, it's about 2 miles less in the 535i, than the 330d.

Must be the 'low flying' when the wheels are off the ground.

HighlandPete

Mr. Grumpy · 07-12-2013, 12:35 PM

Quote:

Originally Posted by FnoFFen

What is a odometer?

The Kilometers / Miles traveled counter.

Mr. Grumpy · 07-12-2013, 12:55 PM

No, it's a different menu. You can see how to access both menus from this video.

FnoFFen · 07-13-2013, 12:40 PM

Thanks to Grumpy for that convenient recipe

.

Higher or lower depends on if your consumption is rated in l/100 km or mpg. So, if my real consumption is 8.65 l/100 km and the computer says 8.0 l/100 km, I set the correction factor to 925 or 1081?

Do you think doing correction in these menues can affect the warranty in any way?

Mr. Grumpy · 07-13-2013, 03:29 PM

Set the correction factor to 925 and start from there. Do at least two fuel tank runs before tweaking.

This will not void your warranty since you're not altering the vehicle electronics, you're just adjusting the correction factor.

STOOF · 07-13-2013, 05:18 PM

I noticed mine shows im getting 1.5 mpg more than actual, so i def need to do this.

snj1013 · 07-16-2013, 03:21 PM

Quote:

Originally Posted by FnoFFen

Thanks to Grumpy for that convenient recipe

.

Higher or lower depends on if your consumption is rated in l/100 km or mpg. So, if my real consumption is 8.65 l/100 km and the computer says 8.0 l/100 km, I set the correction factor to 925 or 1081?

Do you think doing correction in these menues can affect the warranty in any way?

A correction factor greater than 1000 will correct a computer than is underestimating the amount of fuel the car is using. Mine is set at 1060.

FnoFFen · 07-16-2013, 03:38 PM

Quote:

Originally Posted by snj1013

A correction factor greater than 1000 will correct a computer than is underestimating the amount of fuel the car is using. Mine is set at 1060.

Sure? Because this is the opposite of what Grumpy is saying.

snj1013 · 07-16-2013, 03:40 PM

Grumpy is wrong. I think he is confused that the numbers given are fuel/mile rather than how we normally quote in the states as miles/gallon.

Mr. Grumpy · 07-16-2013, 08:42 PM

Quote:

Originally Posted by snj1013

Grumpy is wrong. I think he is confused that the numbers given are fuel/mile rather than how we normally quote in the states as miles/gallon.

I did this in my car and it worked. My car was reading close to a Gal over and after a few tweaking sessions my final number was 1035. My MPG's are now on the spot according to my comparisons with Fuelly website, that's why I know that this is the correct way of correcting the MPG reading.

snj1013 · 07-16-2013, 09:50 PM

Grumpy, you have the same issue I had, and the same issue the OP has. A number greater than 1000 will correct for the computer over metering fuel. You recommended a value of 925.

steve-p · 07-20-2013, 04:49 AM

Maybe I have the record for the most inaccurate MPG reading but I got mine almost spot on. It still differs from reality from tank to tank but only by 0.1 MPG in either direction. I had to use 1090 (car was originally optimistic by nearly 10%).

Is there anything else interesting in that service menu I wonder. I didn't dare change anything else

07-12-2013, 07:54 AM	#1
FnoFFen New Member 16 Rep 29 Posts Drives: 525d 2011 saloon, space grey Join Date: Jun 2013 Location: Karmoy, Rogaland, Norway iTrader: (0)	Why is the fuel consumption in the onboard computer always wrong? Again. My new 2011 525d got it wrong again. My onboard computer tells me my average fuel consumption for small distances is 8.0 liter per 100 km (29.5 mpg). When I check, however, it is 8.7 liter per 100 km (27 mpg). This has been like this in all my three BMWs. The computer always shows less consumption than real. Since it seems like a systematic error what should be the problem getting it right?
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07-12-2013, 08:21 AM	#2
Mr. Grumpy BMW Enthusiast 25 Rep 303 Posts Drives: 2022 X5 Join Date: Mar 2010 Location: Home of the brave. iTrader: (2)	You can adjust this in the hidden menu of your instrument cluster. Mine was almost 1.2 Gal. off and after tweaking the values in the menu is on the spot now. __________________ 2022 X5 sDrive 40i Carbon Black \| Ivory White Vernasca Leather \| Aluminum Tetragon Trim \| ZMP \| ZPP \| ZLS \| ZPK \| 337 \| 4NB \| 3M2 \| 4HB \| 7M9 \| Black Kidney Grills \|
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07-12-2013, 10:29 AM	#3
dbs600 Colonel 266 Rep 2,246 Posts Drives: 2011 750LXi Individual Join Date: Apr 2010 Location: New York, NY iTrader: (0)	Do you have a link to instructions on how to adjust this? Thanks!
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07-12-2013, 10:36 AM	#4
Mr. Grumpy BMW Enthusiast 25 Rep 303 Posts Drives: 2022 X5 Join Date: Mar 2010 Location: Home of the brave. iTrader: (2)	1. Hold down the odometer reset button and turn the ignition on by pushing start/stop button. 2. Release the odometer reset button, and you should see a menu of 4 items on the dashboard. From here on, use the odometer-reset button to advance to the next entry through a short press, and to select through a long press. 3. Choose the one that says Unlock through the above, which will take you to a passkey screen. Your passkey is the sum of the last 5 digits of your VIN. Increment the two-digit number until you get to it, and with the long press of the odometer button, select it. 4.Then scroll down to correction factor and modify it from 1000 to whatever you require. If your trip computer reads higher than true figures worked out, make the correction over 1,000. If your trip under reads, make the correction number under 1,000. Copied from Chuck W. post. __________________ 2022 X5 sDrive 40i Carbon Black \| Ivory White Vernasca Leather \| Aluminum Tetragon Trim \| ZMP \| ZPP \| ZLS \| ZPK \| 337 \| 4NB \| 3M2 \| 4HB \| 7M9 \| Black Kidney Grills \|
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07-12-2013, 11:21 AM	#5
FnoFFen New Member 16 Rep 29 Posts Drives: 525d 2011 saloon, space grey Join Date: Jun 2013 Location: Karmoy, Rogaland, Norway iTrader: (0)	What is a odometer?
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07-12-2013, 12:16 PM	#6
HighlandPete Lieutenant General 6659 Rep 15,858 Posts Drives: BMW F11 535i Touring Join Date: Mar 2007 Location: Scotland, Highland Region iTrader: (0)	My BMW's OBC have always been very accurate against brim to brim checks. The E91 330d changed after a software update, went to reading about 10% lower than actual, had been less than 1% difference from new, reading on the optimistic side. Current F11 is within 0.5mpg (imperial gallons) around the 30mpg range, again OBC reads on the optimistic side. But we do have to allow for other build and running tolerances. One trip I make is about 90 miles, it's about 2 miles less in the 535i, than the 330d. Must be the 'low flying' when the wheels are off the ground. HighlandPete
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07-12-2013, 12:55 PM	#8
Mr. Grumpy BMW Enthusiast 25 Rep 303 Posts Drives: 2022 X5 Join Date: Mar 2010 Location: Home of the brave. iTrader: (2)	No, it's a different menu. You can see how to access both menus from this video. __________________ 2022 X5 sDrive 40i Carbon Black \| Ivory White Vernasca Leather \| Aluminum Tetragon Trim \| ZMP \| ZPP \| ZLS \| ZPK \| 337 \| 4NB \| 3M2 \| 4HB \| 7M9 \| Black Kidney Grills \|
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07-13-2013, 12:40 PM	#9
FnoFFen New Member 16 Rep 29 Posts Drives: 525d 2011 saloon, space grey Join Date: Jun 2013 Location: Karmoy, Rogaland, Norway iTrader: (0)	Thanks to Grumpy for that convenient recipe . Higher or lower depends on if your consumption is rated in l/100 km or mpg. So, if my real consumption is 8.65 l/100 km and the computer says 8.0 l/100 km, I set the correction factor to 925 or 1081? Do you think doing correction in these menues can affect the warranty in any way?
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07-13-2013, 03:29 PM	#10
Mr. Grumpy BMW Enthusiast 25 Rep 303 Posts Drives: 2022 X5 Join Date: Mar 2010 Location: Home of the brave. iTrader: (2)	Set the correction factor to 925 and start from there. Do at least two fuel tank runs before tweaking. This will not void your warranty since you're not altering the vehicle electronics, you're just adjusting the correction factor. __________________ 2022 X5 sDrive 40i Carbon Black \| Ivory White Vernasca Leather \| Aluminum Tetragon Trim \| ZMP \| ZPP \| ZLS \| ZPK \| 337 \| 4NB \| 3M2 \| 4HB \| 7M9 \| Black Kidney Grills \|
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07-13-2013, 05:18 PM	#11
STOOF Sunburned 238 Rep 1,097 Posts Drives: '16 F83 M4 Convertible 6MT Join Date: Jul 2009 Location: Staten Island, NY iTrader: (2) Garage List 2013 BMW 535i [0.00]	I noticed mine shows im getting 1.5 mpg more than actual, so i def need to do this. __________________ 2016 M4 Convertible 6MT - SO/SO 2013 535i 6MT MSport - Retired 2011 Z4 SDrive35i 6MT- Retired
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07-16-2013, 03:40 PM	#14
snj1013 Captain 87 Rep 937 Posts Drives: 2011 528i Join Date: Jul 2011 Location: Houston, TX iTrader: (1)	Grumpy is wrong. I think he is confused that the numbers given are fuel/mile rather than how we normally quote in the states as miles/gallon.
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07-16-2013, 09:50 PM	#16
snj1013 Captain 87 Rep 937 Posts Drives: 2011 528i Join Date: Jul 2011 Location: Houston, TX iTrader: (1)	Grumpy, you have the same issue I had, and the same issue the OP has. A number greater than 1000 will correct for the computer over metering fuel. You recommended a value of 925.
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07-20-2013, 04:49 AM	#17
steve-p Second Lieutenant 5 Rep 241 Posts Drives: 2012 ActiveHybrid 5 Join Date: Mar 2008 Location: Newbury, UK iTrader: (0)	Maybe I have the record for the most inaccurate MPG reading but I got mine almost spot on. It still differs from reality from tank to tank but only by 0.1 MPG in either direction. I had to use 1090 (car was originally optimistic by nearly 10%). Is there anything else interesting in that service menu I wonder. I didn't dare change anything else
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