Omega Owners Forum

Chat Area => General Car Chat => Topic started by: D on 29 January 2012, 22:29:40

Title: Rubbish OBC
Post by: D on 29 January 2012, 22:29:40
So I get into the car with OBC claiming I have 50 odd miles till empty. Drive rather spiritedly (as much as you can in an Elite) and reach destination (about 16 miles away). Spend a few hours shopping and get back in, drive off and as I canter down the narrow spiral path from the car park my engine cuts out. Takes me a while to realise it was actually dead till I realise that the steering has no power assitance. At this point I am sweating a bit as getting stuck in the narrow track means obstructing the hundreds of Sunday shoppers trying to get home. Thankfully I reacted in time to nudge the gearbox into neutral and coast all the way to the bottom and mount the kerb so as to not obstruct other drivers. At this point I am wondering whats going on as OBC still reads 10 miles to empty, needle in red but not at the very bottom. So I am about to call recovery when I try restarting and the engine fires to life. Excellent, drive off to the nearest petrol station and on route the engine tries to die on me again (twice). Somehow make it to the pump and fill her up (£90  :'(). Restart and no problems ever since. I can only presume the OBC was wrong and I had very little fuel in the tank.

I used to always fill up at the quarter mark, but have been lazy since I changed to the Omega. Lesson learnt. And hopefully no damage done to car. And never believe what the OBC tells you.
Title: Re: Rubbish OBC
Post by: Kevin Wood on 29 January 2012, 22:32:36
The range assumes that your fuel consumption remains constant over the remainder of the tank. Put your clog down and, as you have found, it can look a bit optimistic. The orange light is more trustworthy. ;)
Title: Re: Rubbish OBC
Post by: Lazydocker on 29 January 2012, 22:35:01
Also sounds like you were suffering fuel "slosh" :-\
Title: Re: Rubbish OBC
Post by: Vamps on 29 January 2012, 23:18:59
swmbo has a terrible habit of 'pushing her luck' why o why drive with so little fuel in the car, even if driving to a filling station, it only takes a jam or a diversion and you are up the creek....... ::) ::) ::)
Title: Re: Rubbish OBC
Post by: Webby the Bear on 29 January 2012, 23:37:23
Also sounds like you were suffering fuel "slosh" :-\

What the fek is fuel slosh, LD? lol
Title: Re: Rubbish OBC
Post by: hotel21 on 29 January 2012, 23:44:00
Also sounds like you were suffering fuel "slosh" :-\

What the fek is fuel slosh, LD? lol
Ever put a pint of puke in a large basin and slipped it around?

Thats 'fuel slosh'.....     :y   :-X
Title: Re: Rubbish OBC
Post by: Vamps on 29 January 2012, 23:50:13
Also sounds like you were suffering fuel "slosh" :-\

What the fek is fuel slosh, LD? lol

He's got all technical with his new job...... :D :D :D
Title: Re: Rubbish OBC
Post by: Andy B on 29 January 2012, 23:54:48
....
Ever put a pint of puke in a large basin and slipped it around?

Thats 'fuel slosh'.....     :y   :-X

Wouldn't the diced carrots & tomato skins block the filter ............  ::) ::) ::) ::)  ;D ;D
Title: Re: Rubbish OBC
Post by: dbug on 29 January 2012, 23:56:41
Also sounds like you were suffering fuel "slosh" :-\

What the fek is fuel slosh, LD? lol
Ever put a pint of puke in a large basin and slipped it around?

Thats 'fuel slosh'.....     :y   :-X

Nicely put H21 - hope Webby understands ok ???
Title: Re: Rubbish OBC
Post by: Webby the Bear on 30 January 2012, 00:01:21
Also sounds like you were suffering fuel "slosh" :-\

What the fek is fuel slosh, LD? lol
Ever put a pint of puke in a large basin and slipped it around?

Thats 'fuel slosh'.....     :y   :-X

Nicely put H21 - hope Webby understands ok ???

I presume you're talking about the shite that's been allowed to slosh round the engine due to the fuel going so low. If not, I aint got a fckuing clue what you're talking about  :)
Title: Re: Rubbish OBC
Post by: albitz on 30 January 2012, 00:11:21
Ime they dont tend to start up and drive to the nearest petrol station after they run out (although "slosh" could expllain why it did - maybe) but I would be doing a paperclip test just in case. ;)
Title: Re: Rubbish OBC
Post by: JamesV6CDX on 30 January 2012, 00:13:59
Ime they dont tend to start up and drive to the nearest petrol station after they run out (although "slosh" could expllain why it did - maybe) but I would be doing a paperclip test just in case. ;)

Agreed. On the occasions my Omegas have been "out of juice" - they aren't going anywhere fast until you get a petrol can... ;D
Title: Re: Rubbish OBC
Post by: D on 30 January 2012, 13:49:29
Perhaps the incline of the road? Or maybe slosh. No codes at all.
Title: Re: Rubbish OBC
Post by: aaronjb on 30 January 2012, 14:00:24
Also sounds like you were suffering fuel "slosh" :-\

What the fek is fuel slosh, LD? lol
Ever put a pint of puke in a large basin and slipped it around?

Thats 'fuel slosh'.....     :y   :-X

Nicely put H21 - hope Webby understands ok ???

I presume you're talking about the shite that's been allowed to slosh round the engine due to the fuel going so low. If not, I aint got a fckuing clue what you're talking about  :)

Imagine the fuel tank is the large bowl, and the fuel is the puke.. as you drive around the fuel will move around the tank - since the 'pickup' of the pump is only in one place, all it takes is a hard corner et viola, you're sucking air (or, in the analogy, have puke down your shirt)..
Title: Re: Rubbish OBC
Post by: OOMV6 on 30 January 2012, 14:08:51
So I get into the car with OBC claiming I have 50 odd miles till empty. Drive rather spiritedly (as much as you can in an Elite) and reach destination (about 16 miles away). Spend a few hours shopping and get back in, drive off and as I canter down the narrow spiral path from the car park my engine cuts out. Takes me a while to realise it was actually dead till I realise that the steering has no power assitance. At this point I am sweating a bit as getting stuck in the narrow track means obstructing the hundreds of Sunday shoppers trying to get home. Thankfully I reacted in time to nudge the gearbox into neutral and coast all the way to the bottom and mount the kerb so as to not obstruct other drivers. At this point I am wondering whats going on as OBC still reads 10 miles to empty, needle in red but not at the very bottom. So I am about to call recovery when I try restarting and the engine fires to life. Excellent, drive off to the nearest petrol station and on route the engine tries to die on me again (twice). Somehow make it to the pump and fill her up (£90  :'(). Restart and no problems ever since. I can only presume the OBC was wrong and I had very little fuel in the tank.

I used to always fill up at the quarter mark, but have been lazy since I changed to the Omega. Lesson learnt. And hopefully no damage done to car. And never believe what the OBC tells you.

Still pretty accurate if you ran out at 10 miles to go.
Title: Re: Rubbish OBC
Post by: Lazydocker on 30 January 2012, 17:40:53
Also sounds like you were suffering fuel "slosh" :-\

What the fek is fuel slosh, LD? lol
Ever put a pint of puke in a large basin and slipped it around?

Thats 'fuel slosh'.....     :y   :-X

Nicely put H21 - hope Webby understands ok ???

I presume you're talking about the shite that's been allowed to slosh round the engine due to the fuel going so low. If not, I aint got a fckuing clue what you're talking about  :)

Imagine the fuel tank is the large bowl, and the fuel is the puke.. as you drive around the fuel will move around the tank - since the 'pickup' of the pump is only in one place, all it takes is a hard corner et viola, you're sucking air (or, in the analogy, have puke down your shirt)..
Exactly as above. The main reason I suspect it in this instance is because he was going down a spiral when it cut out ;)

As said though, worth checking the codes just in case :y
Title: Re: Rubbish OBC
Post by: TheBoy on 30 January 2012, 18:26:48
You're all barking up the wrong tree...  ...OP has clearly stated the cause ;)
Title: Re: Rubbish OBC
Post by: Lazydocker on 30 January 2012, 19:45:21
You're all barking up the wrong tree...  ...OP has clearly stated the cause ;)

Well, this is true... He gave it an enthusiastic drive there, but strange that it was re-starting
Title: Re: Rubbish OBC
Post by: TheBoy on 30 January 2012, 22:05:34
You're all barking up the wrong tree...  ...OP has clearly stated the cause ;)

Well, this is true... He gave it an enthusiastic drive there, but strange that it was re-starting
I'm talking about the BC Range inaccuracy...
Title: Re: Rubbish OBC
Post by: TheBoy on 31 January 2012, 20:50:05
To help the OP, although I know its not urgent...

...where does the BC get its tank contents signal from...   ...instrument ECU for those that don't know.

...OP said the gauge didn't read empty, so clearly the BC will have the same view.



So ultimately, its likely to be the float reading isn't accurate when low on the OP's car. Or the Instrument panel has the wrong programming.
Title: Re: Rubbish OBC
Post by: Kevin Wood on 31 January 2012, 22:35:13
To help the OP, although I know its not urgent...

...where does the BC get its tank contents signal from...   ...instrument ECU for those that don't know.

...OP said the gauge didn't read empty, so clearly the BC will have the same view.



So ultimately, its likely to be the float reading isn't accurate when low on the OP's car. Or the Instrument panel has the wrong programming.

It actually uses the same input signal as the instrument ECU, IIRC, not even an output from the instrument ECU, so likely the float has stuck above the bottom of the tank IMHO.

In this scenario (same situation as with LPG) it appears to guesstimate based on tank contents at each start and consumption until it's almost empty, then start counting down the miles. If the float sicks before it starts counting down it will be a tad optimistic. ;)
Title: Re: Rubbish OBC
Post by: TheBoy on 31 January 2012, 22:40:28
To help the OP, although I know its not urgent...

...where does the BC get its tank contents signal from...   ...instrument ECU for those that don't know.

...OP said the gauge didn't read empty, so clearly the BC will have the same view.



So ultimately, its likely to be the float reading isn't accurate when low on the OP's car. Or the Instrument panel has the wrong programming.

It actually uses the same input signal as the instrument ECU, IIRC, not even an output from the instrument ECU, so likely the float has stuck above the bottom of the tank IMHO.

In this scenario (same situation as with LPG) it appears to guesstimate based on tank contents at each start and consumption until it's almost empty, then start counting down the miles. If the float sicks before it starts counting down it will be a tad optimistic. ;)
need to check schems, but if instrument panel missing, I know BC cannot read tank
Title: Re: Rubbish OBC
Post by: Kevin Wood on 31 January 2012, 22:46:39
To help the OP, although I know its not urgent...

...where does the BC get its tank contents signal from...   ...instrument ECU for those that don't know.

...OP said the gauge didn't read empty, so clearly the BC will have the same view.



So ultimately, its likely to be the float reading isn't accurate when low on the OP's car. Or the Instrument panel has the wrong programming.

It actually uses the same input signal as the instrument ECU, IIRC, not even an output from the instrument ECU, so likely the float has stuck above the bottom of the tank IMHO.

In this scenario (same situation as with LPG) it appears to guesstimate based on tank contents at each start and consumption until it's almost empty, then start counting down the miles. If the float sicks before it starts counting down it will be a tad optimistic. ;)
need to check schems, but if instrument panel missing, I know BC cannot read tank

I'm guessing the instrument panel provides a current source, and reads voltage developed across the resistance of the sensor whereas the MID just samples the voltage on the same line (as does the engine ECU, for some reason - purge control, I guess).
Title: Re: Rubbish OBC
Post by: robmac on 01 February 2012, 08:55:51
once my obc states there is only 30 miles worth of fuel by flashing the fact i usually fill up pretty soon to be on the safe side!!