[Dan-]

Hi everyone, Some of you may be aware that awhile ago i had an issue with my MPG i was only averaging 15-17mpg in my 335D, i was advised to check the operating temperature and sure enough it wasn't getting up to temp 60-72 was where it was at, changed both thermostats with genuine BMW items and sure enough my MPG improved but only slightly to an average of 24mpg on board computer.

I have been to see Steve at A1BN and he was very helpful and run a in-depth diagnostic for me and the only fault showing was the fuel filter, I changed that and cleared the code and it has not shown back up.

I went back to see him as he recommend doing an Engine parameter reset but unfortunately my car for some reason will not give him option to do so.

Ive since been manually calculating my MPG by brimming the tank and letting it run down to quarter and refilling to full noting down my miles covered on that tank of fuel and using Litres to gallons conversions then divided the miles covered by gallons used and sure enough its been totally different to my on board figure.

1st tank i averaged 34.5MPG covering 352 miles
2nd tank i averaged 35.2MPG covering 360 miles
3rd tank i averaged 29MPG covering 334 miles i had been giving it some torture on that tank

Each time the on board computer was showing 22-25 MPG no matter how carefully i drive it, soon as i accelerate from a roundabout up to 60-70 manually changing gear with the paddles in D so it doesn't rev past 2.5k it just drops like a lead ballon and the figure wont go back to what it should be showing, just stays low.

I know something has happened as when i bought the car back in January last year i was chuffed to but with it it was always in the high 30's obviously got more confident in it so that dropped slightly but even when i did a few 0-155mph run I've got videos of the of the trip showing 29 average, if i do 200 miles now and then do a 0-100 when the current average is say 26 the average will just drop right down to 20-22 even after covering 200 miles

Apologies for the long read but, I'm kind of lost on what i can do next?

Any help would be appreciated.

Regards

Dan

[grimwood1992]

well i suppose the plus is you havent burnt as much cash as you thought on petrol

very annoying that the MPG on the dash is incorrect. i always wonder how accurate it was because on a 320i mine averages about 22-25 which im sure is incorrect on a 2 litre. Ill be very interested to know the answer to this. maybe there is someway of calibrating it :/

[Dan-]

That is a bonus, I sold my 550bhp Impreza to buy this as i was getting fed up with the 12-15mph it was returning on my long drive to work, and now everyone keep reminding me that I've got a diesel and its not much better.

Hopefully there is that someone will know.

[Dan-]

Im not sure how many people would have done this and have current Mpg showing

i know a car that will do that speed obviously isn't going to average 30mpg at these speeds but 10 surely thats not normal?

Private Road

[holmefield]

Originally Posted by Dan-

Im not sure how many people would have done this and have current Mpg showing

i know a car that will do that speed obviously isn't going to average 30mpg at these speeds but 10 surely thats not normal?

Private Road

Please tell me somebody took that photo for you whilst you were doing north of 150mph????

Can you not reset the OBC? As in a factory reset using Bmwhat App or summut..

[Dan-]

Originally Posted by holmefield

Please tell me somebody took that photo for you whilst you were doing north of 150mph????

Can you not reset the OBC? As in a factory reset using Bmwhat App or summut..

Oh hell yeah!!! that would have been stupid and suicidal at those speeds, the quarry entrance road i was on wasn't the smoothest road ever although 3miles straight had just been laid

Ive trield looking through all the BMWhat app functions can see nothing

[Dan-]

Will also note i have also had a new battery fitted and coded correctly as mine was failing so i though maybe its thats causing a few issues.

[Ess]

Originally Posted by Dan-

Oh hell yeah!!! that would have been stupid and suicidal at those speeds, the quarry entrance road i was on wasn't the smoothest road ever although 3miles straight had just been laid

Ive trield looking through all the BMWhat app functions can see nothing

Dan, on mine, coding anything on the dashboard (KOMBI?) with BMWhat causes the dash to reset - I then have to reset the time and lose all the MPG/MPH/odometer values. Perhaps try that? E.g. digital speedometer to on.

Very strange problem you are describing

[Dan-]

Originally Posted by Ess

Dan, on mine, coding anything on the dashboard (KOMBI?) with BMWhat causes the dash to reset - I then have to reset the time and lose all the MPG/MPH/odometer values. Perhaps try that? E.g. digital speedometer to on.

Very strange problem you are describing

Ohh yeah it does reset the time and dates etc, but the all the drive setting are still saved and journey computer etc so i dont think that does a complete reset,

I've turned off instant mpg off and that did the reset :/

Very strange, literally scratching my head, I even have to turn 2nd window in idrive to display nav and digital speedo in my speedo cluster so i cant see my mpg figure

[makkan00]

Are you referring to instant MPG figures or Average MPG figures?
And are you saying that your average MPG figures are lower than actual brim to brim average mpg?

[Dan-]

Originally Posted by makkan00

Are you referring to instant MPG figures or Average MPG figures?
And are you saying that your average MPG figures are lower than actual brim to brim average mpg?

Im referring to Average figure Sam, your 2nd line is correct

[makkan00]

In that case, I will give you a hint.
Search for hidden menu.
Find the fuel correction factor.
You find the value :
Actual MPG/ Displayed MPG X 1000

And you will have to enter that in the hidden menu to correct your mpg difference.

PS: This is from the top of my head so kindly search it thoroughly before you do it.

[Ess]

Originally Posted by Dan-

Ohh yeah it does reset the time and dates etc, but the all the drive setting are still saved and journey computer etc so i dont think that does a complete reset,

I've turned off instant mpg off and that did the reset :/

Very strange, literally scratching my head, I even have to turn 2nd window in idrive to display nav and digital speedo in my speedo cluster so i cant see my mpg figure

Ah fair enough Dan, I don't have iDrive sadly in my car so not sure how the app affects it.

I suppose the main thing is that the consumption is actually okay, but it is annoying that the reading is erratic. I'm afraid I don't know what to suggest

[Dan-]

Originally Posted by makkan00

In that case, I will give you a hint.
Search for hidden menu.
Find the fuel correction factor.
You find the value :
Actual MPG/ Displayed MPG X 100

And you will have to enter that in the hidden menu to correct your mpg difference.

PS: This is from the top of my head so kindly search it thoroughly before you do it.

Thanks for that much appreciate it. Is it widely posted online?

[MrPogle]

Might be worth checking the calibration factor on your fuel computer via the hidden menu. It should be 1000 by default and you often need to adjust them by plus/minus 50ish to get the best accuracy. Sometimes dealers deliberately adjust them to give flattering figures to test drivers.

[Dan-]

Originally Posted by Ess

Ah fair enough Dan, I don't have iDrive sadly in my car so not sure how the app affects it.

I suppose the main thing is that the consumption is actually okay, but it is annoying that the reading is erratic. I'm afraid I don't know what to suggest

Thats okay thanks for trying hopefully what Sam has posted above will have some affect

[makkan00]

Originally Posted by Dan-

Thanks for that much appreciate it. Is it widely posted online?

I may have read it multiple times but never make note of it.
My last two cars were remapped so car mpg was always optimistic.

Here is example of it being done on F10

It is very similar to that on E-series.
You enter the unlocking code (add last 5 digits of vin) on option 19 in kombi / speedometer.

And then I think it is number 20-20.3 in the hidden menu for e-series or something like that to adjust the value.

If your last 5 digits are 12345 then your unlocking code will be 15.

IF your actual average mpg is 30 and your displayed is 25 then
30/25X1000= 1200 is the value which you should enter. So you add 200 to the value and I think you use 20.03 hidden menu if you have to change it in hundreds.


Mr poogle is thinking on right lines. That is how you start and then adjust it after running few tanks.

HTH.

[Dan-]

Just been to have a look, and its all over the damn place, goes from 800-1289 just counts ups on every option of 20 ?

[Dan-]

This is what mine is doing, excuse Slipknot playing in the background 😂

[Dan-]

I think i have just figured it out, the 1st number that flags up is the current which the 1st time i looked it was 1234 then i clicked and must have changed it so the 2nd time i opened the screen in the video above it started on 1098?

Ive worked out the calculation which is

1234 x 7.3l/km (32mpg) / 10.2l/km (23mpg) = 883

How does that look?

[makkan00]

Originally Posted by Dan-

I think i have just figured it out, the 1st number that flags up is the current which the 1st time i looked it was 1234 then i clicked and must have changed it so the 2nd time i opened the screen in the video above it started on 1098?

Ive worked out the calculation which is

1234 x 7.3l/km (32mpg) / 10.2l/km (23mpg) = 883

How does that look?

You can see in the video that 20.1 is single digit correction factor.
20.2 in 10s.
20.3 in 100s.

As per your figures, your value should be 1391.
I think it allows you to go max to 1250.

And I think you are going the other way around and decreasing it.

[Dan-]

I've set values to 883 and gone for a 44 miles drive at 60-70mph exactly as I did when I purchased the car I managed 46.5 the day I got the car and tonight I've just managed 47.8

So I'm going to keep an eye on it over the next few fill ups and hope I'm not far out and just adjust it as needed.

Thanks for all the help and advice