Don't Stop!! Don't Stop!!!!

[Truvalu]

I have to share this with you.....

My 1997 528i E39 was near empty on Friday.
I put in 15litres on Friday.
Hardly ever drove over the weekend.

This morning as I took my son to school I saw the fuel warning light on, but didn't take much notice as I know I must have about 10litres in at least... trip meter shows 35km since I added the 15litres.

This afternoon as I got in the car to go fetch my son, I got a bit rattled.... Needle is under zero and light on...

Now I switch to range left till empty and it shows 15km.

I think, ok that's fine is about 6km to fetch, drop-off at home and get back to work. OBC shows 13.3L/100km.

Now comes the good part... the further I drove the more the range becomes.

As I stopped at my office, it is showing 88km till empty. Now that is from 15km's before!!

The needle is now showing about 10L left in the tank where it was under empty just now....

Now I wonder... if I just kept driving and driving... would I land up with a full tank????

Any light on the subject?

 

[zaleonardz]

Well, there can be a host of reasons for this

Faulty fuel sender unit
You were parked at an angle

What it does is it works on an average, at idle you are chewing petrol like there is no tomorrow, so if the car has been idling, you will reach heavy consumption figures.

If you then drive it like a gentleman, it compensates hence the increased range.

Or it could be based on the same theory as Microsoft time... then who knows how the f it calculates...

 

[Truvalu]

Well, there can be a host of reasons for this

Faulty fuel sender unit
You were parked at an angle

What it does is it works on an average, at idle you are chewing petrol like there is no tomorrow, so if the car has been idling, you will reach heavy consumption figures.

If you then drive it like a gentleman, it compensates hence the increased range.

Or it could be based on the same theory as Microsoft time... then who knows how the f it calculates...

Thanks Mr Z....

Maybe it is the gentleman's bit, but that could not make the needle climb from under zero to about 10Litres, could it?

Maybe the correct idea would be to have it full, most of the time.... but you know.... so little petrol, so much month left...

 

[zaleonardz]

The only real way to check it is to always fill your tank, that way, you know how many litres your putting in, and you will know what a tank should give you.

That will also give you an idea if anything is wrong with your car, but I hear you man. I filled the 7 on sunday, and the 5 today... over R1,200 for that one thank you very much...

 

[Truvalu]

Size of the tanks?

Do you fill it till the nozzle clicks first time, or do you FILL it?

Some places fill it in such a way, I am sure they would use a broomstick to get more in, if they could.....

 

[rick540]

It's constantly re-calculating range. The position of the fuel guage is actually pinned by the computer and not the level sender.

Somewhere in the owners manual if you don't fill up very often, they recomend every few months to "reset" it, you need to run the tank to almost empty then fill her up.

 

[Beast_Power]

Could you please tell me where you last filled up, as some of that self replicating fuel will be a welcome addition to my fuel tank !

 

[rick540]

I'll never forget when my local BP had a dodgey pump....... Got a 90L tank for R150

 

[Truvalu]

It's constantly re-calculating range. The position of the fuel guage is actually pinned by the computer and not the level sender.

Somewhere in the owners manual if you don't fill up very often, they recomend every few months to "reset" it, you need to run the tank to almost empty then fill her up.

If I understand correctly then.... the Fuel guage is not mechanical, but electronic.... the level sender thus commanding the computer and that then determines the stance of the fuel guage?

 

[rick540]

It's constantly re-calculating range. The position of the fuel guage is actually pinned by the computer and not the level sender.

Somewhere in the owners manual if you don't fill up very often, they recomend every few months to "reset" it, you need to run the tank to almost empty then fill her up.

If I understand correctly then.... the Fuel guage is not mechanical, but electronic.... the level sender thus commanding the computer and that then determines the stance of the fuel guage?

Yep

 

[Truvalu]

It's constantly re-calculating range. The position of the fuel guage is actually pinned by the computer and not the level sender.

Somewhere in the owners manual if you don't fill up very often, they recomend every few months to "reset" it, you need to run the tank to almost empty then fill her up.

If I understand correctly then.... the Fuel guage is not mechanical, but electronic.... the level sender thus commanding the computer and that then determines the stance of the fuel guage?

Yep

See.... now that's why I love these machines so much!!! If it was any of my previous cars, I would've thought it is broken....... again!!!

 

[Twinz]

That stretch to school is known as "Bermuda Triangle"...

 

[Truvalu]

That stretch to school is known as "Bermuda Triangle"...

Oh.... how I love to get lost!!!!

 

[rick540]

Well, electronic is nice and clever.

But

I remember when I managed to delete my cars coding by mistake and fiddling too much.... almost everything stopped working, and the guages were going totally crazy like they were posessed jumping around the dials, lights going on an off....... was truly terrifying, now that was Bermuda triangle stuff.

It was early days, so had to go to Forsdicks BMW and "Lie" that it just did that when I jump started it, they recoded it for free but I remember the workshop manager Eugene shaking his head and muttering he'd never ever seen this before....... Lol I'm sure he hadnt.

A few months later I did admit to him, it was me that wiped the coding by mistake.

These days I can do my own coding, and feel a little less scared.

They are very software driven, scarily so sometimes.

 

[Truvalu]

Well, electronic is nice and clever.

But

I remember when I managed to delete my cars coding by mistake and fiddling too much.... almost everything stopped working, and the guages were going totally crazy like they were posessed jumping around the dials, lights going on an off....... was truly terrifying, now that was Bermuda triangle stuff.

It was early days, so had to go to Forsdicks BMW and "Lie" that it just did that when I jump started it, they recoded it for free but I remember the workshop manager Eugene shaking his head and muttering he'd never ever seen this before....... Lol I'm sure he hadnt.

A few months later I did admit to him, it was me that wiped the coding by mistake.

These days I can do my own coding, and feel a little less scared.

They are very software driven, scarily so sometimes.

Now that's why I am soooo glad I know you!

A very long time ago I realised that it is worse to think you have knowledge of computers and electronics... or anything for that matter, than not having any at all....

 

[applehero]

Is there a possibility that your son took the car out for a joy ride?!? :mmm:

 

[Hellas]

Is there a possibility that your son took the car out for a joy ride?!? :mmm:

Yeah, and he filled it up with some petrol. Just like the kid who panelbeat'd his dad's car after a night on the town and saw a dent in the car, only to find out that it was the dad that originally put the dent in the car the day before...

 

[Truvalu]

Soooo.... it happened to me too!

Yesterday I drove all over between Paarl, Parow, Stellenbosch, Plattekloof and on my way back to Paarl from Plattekloof.. just going past Engen 1Stop, my computer tells me another 160km till empty, and the guage is just above 15litres, so here I gooi.... going to Paarl!

Just past the Stellenbosch turn-off I RAN OUT!!!!!

I had to walk back to Engen 1Stop (nobody pick anybody up anymore) and got 2 Icecream juice 5L bottles filled with fuel. Luckily two guys on their way home to Drakenstein correctional services (thanks guys!) gave me a lift back to my dry car when I asked them.

Then I realised you cannot just gooi fuel into this baby, there are flaps and and and...

Well I eventualy got going and I realised that you can't trust the guages and computers at all!

Just keep her filled up and you will not have these problems....

 

[rick540]

Oooops....., that's just not right.....

There might be a bit of dirt in there

Next full tank, buy a bottle of redex or fuel injector cleaner, and throw that in, see if it helps.

Will clean the sender up a bit, remove any moisture etc.

I've run my 540 right till under 15Km range a few times.

Also these cars are a bit complex, Though I don't know exactly how to do it there is a fuel calibration correction factor that you can program into the computer to get it 100% accurate, this is done at the factory. You would manually need to record consumption over a few tanks first.

 

[E39 Ian]

very interesting.....as someone who runs close to the bone....good to know :thumbsup: