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Discussion Starter · #1 ·
Alright guys,

I went to a University reunion last weekend, one of my old housemates' brother is a BMW technician and he told me how to recalibrate the MPG aspect of the trip computer for my E90. I've done it twice now as my first effort was a little over zealous and I averaged 57mpg driving home! Anyway, my trip computer is now accurate to within 1 or 2 mpg over a 600 mile tank of the oily stuff.

It's quite a long-winded process (similar to the E46 - but slightly different)and would take a little while to type, BUT, if there is someone out there who's computer is way out, then let me know and I'll do my best.

BTW - this is only possible to do if you have the figures to hand (that is the ACTUAL mpg and the computer mpg) - for example - my last 2 tankfuls have returned 48mpg, but the trip shows 52mpg etc etc.
 
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Discussion Starter · #2 ·
I've now got my trip-computer totally accurate, and in a moment of boredom, i typed this out. I hope it helps and makes sense. Here goes . . . . .


Before you start, do the following sum – Computer MPG divided by Actual MPG, and then multiply the answer by 1000. (Before the mathematicians moan, the trip works in L/km – inverse to MPG!!!) You should get an answer around 1000 (say 850 to 1150 ish)

1) Put the key fob in the dash, get the car to the point where just the oil light is on (not the ABS, airbag etc) You may need to press the start button a few times to get here, but do it without your foot on the clutch.

2) Press the trip reset button (small thin button on left of instrument cluster) for about 15 seconds, during this time, a yellow triangle will appear – keep holding the button down until the display shows something similar to YZ12789. Above this in smaller text there will be “01.00”

3) This is important. Add up the five single numbers in the YZ bit – eg 1 + 2 + 7 + 8 + 9 = 27. This (27) is the unlock code.

4) The 01.00 bit is a bit like a mobile phone menu. You are in menu section 01, looking at sub-menu 00

5) Now hold the trip reset button for about 5 seconds until 01.00 changes to 01.__. When this appears let go of the button.

6) Now press the trip reset button repeatedly until you reach 19.__ . Below it you’ll see “LOCK” and below that “00”. At this point stop pressing the button and pause a moment.

7) Now press trip reset button repeatedly until the “00” reads as your unlock code (e.g. 27), once you reach this number, pause for a second and LOCK will change to “UNLOCK”. The hidden menus are now unlocked – there are 21 different menus and a few sub menus in each. I’d advise you to leave them all alone except menu 20.

8) Press and hold the trip reset button for a few seconds until 19.__ is shown, then release.

10) Press trip reset once so that 20.__ is displayed (menu 20 is the MPG menu) Underneath that will be the number “1000”. This is the multiplication factor for your mpg.

11) Now remember the number I got you to calculate at the start (around 1000) you need to change the factor to this number. It’s a bit like setting a cheap digital watch and although there are 4 digits ( 1 0 0 0 ) they are split into 3 parts (10, 0, 0)so you have only 3 numbers to change. For reference, my number was 888 – but you could have 945, 1034, 1155, 1253 etc etc

12) Press the trip reset button once and the ‘0’ on the right will cycle from 0-9 , press the button when it reaches the number you want (8 in my case). The 2nd ‘0’ then cycles 0-9 – do the same again. Finally, the remaining 2 digits (10) cycle between 7 and 12 – press the button when you want it to stop (again, 8 in my case). So I ended up with 888 as my figure. This is the factor changed – well done!

13) Finally, you need to relock your menus. Press the button for a few seconds until you get 20__, then press repeatedly until you get to menu 19.00. At this point you either enter the unlock code again (the sum of the five numbers) or sometimes mine automatically locks if I pause for a while. Either way, make sure you see “LOCK” and then press your key fob to remove your key. Finished!

You may need to adjust that factor slightly, but over time you can fine-tune it to be perfect. Good luck men!
 

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Your car is under estimating, my car is over estimating. How about we force our cars into an arranged marriage and they'll produce some sort of hybrid that's actually reasonably accurate? Can 320ds breed?
 

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I'm not sure, but with 67mpg, you're is definitely the girl... lol

I don't thrash my 320D (not even sure if it's possible with 150 ponies...) but I do have a spirited right foot. But some people with 330d autos claim their getting better miles.

sdp, how many miles do you get to a full tank?
 

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If I'm really being a "girl" as you put it ;), I can get 675 before I bottle it and have to fill up. Typical driving for me (i.e. thrashing it every now and then on the country roads, but mostly long journeys often with cruise control), I will get 550-600 miles before I decide to fill up. How many miles are you getting to a tank?

I think my real MPG is closer to 49-50, but can get it has high as 54-55 if I'm being a real sissy. Your figure of 37mpg indicates a problem somewhere (hopefully it's just the on-board computer).
 

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I get about 550 miles at best. Most of my weekly driving consists of A and B roads.

Perhaps there is something wrong?! :frown

Car's due an oil change in a few hundred miles... would that make any difference?
 

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I get about 550 miles at best. Most of my weekly driving consists of A and B roads.

Perhaps there is something wrong?! :frown

Car's due an oil change in a few hundred miles... would that make any difference?
Thats probably about right for a full tank doing mainly A & B roads - the only time I get 650ish is when the majority of the tank is on the motorway doing 150+ trips and very little normal road driving.
 

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Discussion Starter · #11 ·
In response to a few PM's and some replies on the thread, I can only guess that the E46 method would be the same except you'd have to put the ignition key in and turn to the first click - the point where the handbrake light etc is on - then the rest is maybe the same. The trip computer is exactly the same on my E46 as it is on the E90 so I reckon it'll work.

Who knows? Good luck!
 

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had a go at this - got to a menu where it says test the 0.__

Scrolled through using the trip reset button until I got to 19. then L-on & L-off were displayed alternately.

When it got to L-off (i'm presuming this is th menu lock) I pressed the button again so unlock menu.

Then cycled through to menu 20 (out of 21) I paused it then goes into menu 21 - I don't see a MPG correction factor in there already just about 5 ------ on the left side of the display - tried all sorts of button combinations but couldn't see a way of entering a correction factor.
 

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Discussion Starter · #13 ·
Ok Fz, I'll get hold of my mate's brother and see if I can find out for you. Congrats on 'getting in' though!
 
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Discussion Starter · #15 ·
Fz, bad news I'm afraid, the man who knows says that the E60 and E90 are the first models where you can recalibrate the computer through the hidden menus.

A good reason to update your car I guess . . . .
 

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I read this thread a while ago, but while in traffic the other day it occured to me that it would be very useful if it was possible to do a similar calibration on the mph setting for the cruise control.

There are a depressing amount of roadworks at the moment covered by average speed cameras and I find cruise control an easy way to stick to 50, say, without losing patience or drifting above the limit.
We all know that there are reasons why the car's main speedo under-reads and that GPS may be more accurate - and happily reads a bit lower than the speedo - so using the GPS speed in these circumstances allows maximum,safe, legal speed.
The mph reading on the cruise control matches the main speedo - but if there is a way to calibrate that reading in the same way as the mpg display it would provide an easier way to set the cruise control at a more accurate speed.

Not sure if that is clear but you probably get the gist.

Anyone any idea if this is possible?

S
 

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I read this thread a while ago, but while in traffic the other day it occured to me that it would be very useful if it was possible to do a similar calibration on the mph setting for the cruise control.

There are a depressing amount of roadworks at the moment covered by average speed cameras and I find cruise control an easy way to stick to 50, say, without losing patience or drifting above the limit.
We all know that there are reasons why the car's main speedo under-reads and that GPS may be more accurate - and happily reads a bit lower than the speedo - so using the GPS speed in these circumstances allows maximum,safe, legal speed.
The mph reading on the cruise control matches the main speedo - but if there is a way to calibrate that reading in the same way as the mpg display it would provide an easier way to set the cruise control at a more accurate speed.

Not sure if that is clear but you probably get the gist.

Anyone any idea if this is possible?

S
i dont think its possible because it can make more problems than resolve any...if you get it wrong it can read like 70mph when you do 50.
 

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My car says i'm getting about 68mpg so i'd be interested in this. I did manage to get 699 miles to a full tank but i was absolutely bricking it in case i ran out, when i filled up it took 62 litres, i believe the tank holds 65 litres.

Shrekster.
 
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