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.

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.

Originally Posted by shodog

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.

ideaphile.com/bmw/540-obc.html

Fair bit down on that page has instructions.

Originally Posted by bmw_n00b13

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?

Originally Posted by grocery_grabber

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 750–1250 range, there's probably something wrong.

TEST-NR. 21
RESET?


Be careful here too—I 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 go—I 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.

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...

Reset just resets the cluster. Shouldn't break anything.

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 .

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.

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. :/

^^this kids higher then Tyrone on Chappelles Show! ahah

Originally Posted by nike001

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

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

Originally Posted by andyffer

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.

Originally Posted by grocery_grabber

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 750–1250 range, there's probably something wrong.

TEST-NR. 21
RESET?


Be careful here too—I 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 go—I 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

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

Originally Posted by crex65439

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.

Originally Posted by crex65439

... 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.