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Go Back   Bimmerfest - BMW Forums > BMW Model Discussions > 5 Series > E39 (1997 - 2003)

E39 (1997 - 2003)
The BMW 5-Series (E39 chassis) was introduced in the United States as a 1997 model year car and lasted until the 2004 when the E60 chassis was released. The United States saw several variations including the 525i, 528i, 530i and 540i. -- View the E39 Wiki

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  #1  
Old 12-14-2009, 08:15 AM
grocery_grabber grocery_grabber is offline
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Is it possible to alter the MPG computer?

My wife complains that the 540 is getting crappy fuel mileage. It does very well (25mpg) on the highway, but around town is another story (15). It's an 03 with Nav.

Is it possible to...
1) Alter the mpg computer to automatically get 4mpg more than it actually is getting?
2) Get rid of this function altogether?

Another weirdity -- if I reset both MPG ratings at the same time and let it go a couple of weeks, the ratings will be different by a significant amount (20%). Trip 1 is always worse than Trip 2.
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  #2  
Old 12-14-2009, 08:46 AM
shodog shodog is offline
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The best way to alter is keep your foot out of the throttle. I like to get on mine and I still get 16.9.
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  #3  
Old 12-14-2009, 08:50 AM
grocery_grabber grocery_grabber is offline
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Originally Posted by shodog View Post
The best way to alter is keep your foot out of the throttle. I like to get on mine and I still get 16.9.
Assume I've already done the basics (keep foot out of it, tires inflated, blah blah). I hate that MPG thing. I want it gone...or hacked.
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  #4  
Old 12-14-2009, 08:58 AM
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bmw_n00b13 bmw_n00b13 is offline
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ideaphile.com/bmw/540-obc.html

Fair bit down on that page has instructions.
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  #5  
Old 12-14-2009, 10:02 AM
grocery_grabber grocery_grabber is offline
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Quote:
Originally Posted by bmw_n00b13 View Post
ideaphile.com/bmw/540-obc.html

Fair bit down on that page has instructions.
The site is down. Can you pls let me know in general what it says?
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  #6  
Old 12-14-2009, 10:10 AM
grocery_grabber grocery_grabber is offline
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Thumbs up

Quote:
Originally Posted by grocery_grabber View Post
The site is down. Can you pls let me know in general what it says?
Nevermind -- Google's caching did wonders. Has anyone tried this?

TEST-NR. 20
KVBR: 1000


This "test" is actually a way to adjust the OBC's fuel consumption factor. There's a sensor in the fuel injector system that indicates fuel consumption back to the OBC. This "KVBR" value is used to calibrate that sensor using the following process:

Reset one of the OBC mileage indicators and the trip odometer, and fill your tank.
Record the actual fuel consumption for your car over a long period (one to two months at least).
Divide this reading into the trip odometer value to calculate your actual mileage.
Divide this result by the OBC indicated mileage over the same period and multiply by 1000.
You now have your fuel consumption factor. To enter the factor into the OBC, get into Test 20 and press Reset. This will start the KVBR value counting down. It will count down to 750, then start over at 1250. A crude user interface to be sure, but it works.

You probably don't need to change the KVBR value; the default value of 1000 should be accurate. And if your calculated fuel consumption factor is outside the 7501250 range, there's probably something wrong.

TEST-NR. 21
RESET?


Be careful here tooI didn't try the Reset button on this one, because I assume it resets the whole OBC. This could be a very bad thing.

So, there you goI hope the fact that I went poking around in my car will satisfy YOUR curiosity. Please don't follow my example unless you know what you're doing and are willing to accept the potentially catastrophic consequences.
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  #7  
Old 12-14-2009, 11:11 AM
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Sounds like your wife has been busy teaching the vtec crew not to mess with 540's at stoplights. She sounds like a good catch to me...
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  #8  
Old 12-14-2009, 12:03 PM
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bmw_n00b13 bmw_n00b13 is offline
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Reset just resets the cluster. Shouldn't break anything.
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  #9  
Old 12-14-2009, 12:36 PM
nike001 nike001 is offline
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Just reset the MPG computer? Just hold in the clicky thing that you use to get to the mpgs/temp/miles til empty thing. When you get to the average mpg's just hold it in. Then just take it easy. I played a game with mine for about a month or so to see how high i could get mine. I had 21.2 max. After I quit it went down..i'm at around 19.5 now. It takes more time for it to build up then it does to fall back down .
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  #10  
Old 12-15-2009, 09:44 PM
wkw wkw is offline
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I did that setting in No. 20. I set it to 1070 I think. its dead on accurate now.

if you want it to read higher than reality, lower the number. I miscalculated at first and set it to 930 and it was reading about 4mpg too high.
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  #11  
Old 12-15-2009, 10:10 PM
andyffer andyffer is offline
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its simple.. just reset it when you are cruising going down a looooonnnnnggggg downhill, wind behind you, type of road and just let off the gas and let nature keep you at your speed
or accelerating a tiny bit

and after an hour of that I think you're set nigga. :\

then when you get into city still be cautious.. give it like 25% throttle, shift low and boom nigga you're in business. :/

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Last edited by andyffer; 12-15-2009 at 10:15 PM.
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  #12  
Old 12-15-2009, 10:30 PM
nike001 nike001 is offline
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^^this kids higher then Tyrone on Chappelles Show! ahah
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  #13  
Old 12-15-2009, 10:46 PM
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QSilver7 QSilver7 is offline
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Quote:
Originally Posted by nike001 View Post
Just reset the MPG computer? Just hold in the clicky thing that you use to get to the mpgs/temp/miles til empty thing. When you get to the average mpg's just hold it in. Then just take it easy. I played a game with mine for about a month or so to see how high i could get mine. I had 21.2 max. After I quit it went down..i'm at around 19.5 now. It takes more time for it to build up then it does to fall back down .
Just an FYI...but there's a slight difference between the LOW & HIGH clusters and LOW & HIGH MIDs & Nav screens on how to reset the OBC features. On the 540i/iT...or the 6 cyl e39s with the HIGH CLUSTER. The AVG MPG (Cons1 & Cons2) are part of the OBC that you access/reset thru the MID or NAV screen.

The high cluster can also be programmed to display the features of the OBC...but to reset any of the OBC features like avg mpg/avg mph...the SET button on the MID is pressed...someone with the Nav system will have to explain how to reset the OBC.

This is an image of one of the CLOCK FACE displays on the MID...but you can see the SET button on the far right which is what is used to reset the AVG MPG (CONS 1 or 2):


low & high MID

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2006 E53 X5 4.4i (Sterling Gray) 12/05 mfg date <<~>> 97 740iL (Arctic Silver) 3/97 mfg date
(SOLD)
99 540iT (Orient Blue) <<~>> 95 525IT (Alpine White)
91 735iL (Schwarz Black) <<~>> 85 325e (Bronzit)

http://imageshack.com/scaled/grid240/822/e38e532ndsigpic.jpg

Last edited by QSilver7; 12-15-2009 at 10:50 PM.
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  #14  
Old 12-16-2009, 02:35 AM
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Bren517 Bren517 is offline
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havent read half the thread but if you have the nav screen just keep it on the home screen with all the main menu's so she cant see it normally when you drive
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  #15  
Old 12-16-2009, 09:31 AM
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bmw_n00b13 bmw_n00b13 is offline
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Quote:
Originally Posted by andyffer View Post
its simple.. just reset it when you are cruising going down a looooonnnnnggggg downhill, wind behind you, type of road and just let off the gas and let nature keep you at your speed
Use the e-meter on the dash. Try to keep it under 10l/100km, whatever that equates to on the US cars. It's not really possible, but keeping an eye on it will change how you drive for the better. I've completely changed how I drive, as a result of that meter. Light on the gas, light on the brakes, and coasting as much as possible will improve the MPG immensely. I make sure to take the car out for some real driving once a week or so, though, and try to get some lengthly 70-80mph highway driving in once in a while.
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'99 528i ('98/12 build). 174,000km BY29428/Royalrot
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Mods: Stoptech SS brake hose, 280piece toolkit resting on trunk floor, Beisan VANOS seals
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  #16  
Old 01-05-2010, 02:13 PM
grocery_grabber grocery_grabber is offline
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Quote:
Originally Posted by grocery_grabber View Post
Nevermind -- Google's caching did wonders. Has anyone tried this?

TEST-NR. 20
KVBR: 1000


This "test" is actually a way to adjust the OBC's fuel consumption factor. There's a sensor in the fuel injector system that indicates fuel consumption back to the OBC. This "KVBR" value is used to calibrate that sensor using the following process:

Reset one of the OBC mileage indicators and the trip odometer, and fill your tank.
Record the actual fuel consumption for your car over a long period (one to two months at least).
Divide this reading into the trip odometer value to calculate your actual mileage.
Divide this result by the OBC indicated mileage over the same period and multiply by 1000.
You now have your fuel consumption factor. To enter the factor into the OBC, get into Test 20 and press Reset. This will start the KVBR value counting down. It will count down to 750, then start over at 1250. A crude user interface to be sure, but it works.

You probably don't need to change the KVBR value; the default value of 1000 should be accurate. And if your calculated fuel consumption factor is outside the 7501250 range, there's probably something wrong.

TEST-NR. 21
RESET?


Be careful here tooI didn't try the Reset button on this one, because I assume it resets the whole OBC. This could be a very bad thing.

So, there you goI hope the fact that I went poking around in my car will satisfy YOUR curiosity. Please don't follow my example unless you know what you're doing and are willing to accept the potentially catastrophic consequences.

Problem solved! Car reads like it's getting 20mpg now. Thanks all
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  #17  
Old 01-06-2010, 02:04 AM
crex65439 crex65439 is offline
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just constantly hide or reset the mpg settings then she cant say anything but what is the test nr 20 thing ? how do you access this
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  #18  
Old 01-06-2010, 11:24 AM
grocery_grabber grocery_grabber is offline
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Quote:
Originally Posted by crex65439 View Post
just constantly hide or reset the mpg settings then she cant say anything but what is the test nr 20 thing ? how do you access this
She's too smart for that. I used to turn it off...but she always brought it back. And if you reset the mpg every time I drove it the mpg went to hell.

The test allows you to change the fuel consumption factor. For example, if the car is getting 17mpg real mileage, you can apply a factor to make the computer think it is getting 12mpg or 21mpg if you wanted by playing with the factor.
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  #19  
Old 01-06-2010, 12:32 PM
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QSilver7 QSilver7 is offline
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Quote:
Originally Posted by crex65439 View Post
... what is the test nr 20 thing ? how do you access this
You have to UNLOCK your car's OBC to access the 21 TESTs that give car info, and OBC calculation info, and some vital electro-mechanical info like battery voltage, alternator/charging system voltage, engine coolant temperature (in Celcius), etc.

If you go to www.bmwtips.com there is a link on how to access these secret or hidden OBC features. Or you can do a search on the E39 forum...the topic has been discussed a lot lately...and more than one of those discussions had the instructions or the link to the instructions.

There's a video on how to unlock the HIGH OBC...not sure if that's what you have or not...but the low OBC UNLOCKING instructions are slightly different since there's only one button on the instrument cluster...plus it doesn't have the 20-digit alpha numeric display.
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2006 E53 X5 4.4i (Sterling Gray) 12/05 mfg date <<~>> 97 740iL (Arctic Silver) 3/97 mfg date
(SOLD)
99 540iT (Orient Blue) <<~>> 95 525IT (Alpine White)
91 735iL (Schwarz Black) <<~>> 85 325e (Bronzit)

http://imageshack.com/scaled/grid240/822/e38e532ndsigpic.jpg
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