3.0d OBC MPG way out of sync + real MPG low

CaseyJay · Post by **CaseyJay** » Sun Jun 05, 2016 1:04 pm

Hi, just I drove 330 miles on a full tank, 250 miles on motorways at steady 135km/h (in France), 12 miles climbing to 800m (gentle incline) and the rest on country roads (50-70km/h), no city driving.

OBC shows an impressive 34.8mpg but I know from experience this is usually way off. Refill this morning and it works out at 23.3mpg. OBC Test 20 factor was 0989 so not far off.

Test 6 shows 82litres when full, although I can squeeze in about 93litres. LH tank guage doesn't work (needle sits on half even when empty).

Anything I can do to bring the computer back in line? And the low mpg on a long run (I've also had 25 on a 800km pure motorway trip) - is that to be expected or something I should address? thx

fenj66 · Post by **fenj66** » Sun Jun 05, 2016 3:23 pm

On test 20 the mpg factor can be set between 750 and 1250 to get the obc in step with actual mpg. With 1000 being the default.
On mine I found 1100 was about correct.
If I set it to 1250 the obc can show an impressive 45mpg!!

fenj66 · Post by **fenj66** » Sun Jun 05, 2016 4:12 pm

Sorry. Just re read and seen you have a diesel.

CaseyJay · Post by **CaseyJay** » Sun Jun 05, 2016 4:55 pm

thanks, I read that ACTUAL / DISPLAYED * 1000 gives me the adjustment factor so 23.3 over 34.8 is out of range so will be more in line but still out which makes me question if there is not another problem somewhere.

And as you say re. V8, if I am going that low, I could nearly justify swapping out for the pleasure/performance of a petrol engine, although in France Unleaded is 20ct a litre dearer...

X5Sport · Post by **X5Sport** » Sun Jun 05, 2016 6:16 pm

Has the car been re-mapped by someone who doesn't know what to do?

Tank is 93-litres. LH sender unit sounds to be faulty. A not uncommon fault. A few folks have changed them on this forum.

CaseyJay · Post by **CaseyJay** » Sun Jun 05, 2016 9:34 pm

hi, you raise a good point, any tips on how I might investigate that aside from looking for a box under the bonnet? ta

Steamyrotter · Post by **Steamyrotter** » Mon Jun 06, 2016 1:17 pm

It is more than likely due to your dodgy second sensor that is causing the issue...

If you work out your 330miles over the 85l, it comes in the 30-35MPG range
Work it to the 95 then it is around 25-28mpg

Computers can only calculate with the information thay have at hand...

fenj66 · Post by **fenj66** » Mon Jun 06, 2016 8:34 pm

Ahem.....Would you like to try those calculations again???

X5Sport · Post by **X5Sport** » Mon Jun 06, 2016 8:38 pm

330/18 gals is around 18.3 mpg (1 gal = 4.546L) if my calculator is working.

Steamy has been exposed to far too much ATF for comfort :blink:

Greydog · Post by **Greydog** » Tue Jun 07, 2016 7:23 am

I knew buying a V8 was the smart thing to do, 19.8 mpg average on the OBC including dragging a horse trailer around.

Steamyrotter · Post by **Steamyrotter** » Wed Jun 08, 2016 1:05 pm

[quote="X5Sport"]
330/18 gals is around 18.3 mpg (1 gal = 4.546L) if my calculator is working.

Steamy has been exposed to far too much ATF for comfort :blink:
[/quote]

It was late..
Had a mental block

And basically cant count for toffee........................

Please ignore any of my previous ramblings as I am obviously not a reliable source!!!!!

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3.0d OBC MPG way out of sync + real MPG low

3.0d OBC MPG way out of sync + real MPG low

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