'KM's left until empty' accuracy?

[gogoboygareth]

A few months ago I ran out of ruel, even though DTE said I had about 80km's to go... driving down the Calder highway, in peak hour traffic. Dammit. The needle was well above the red line... and the warning light wasn't even on.

Since then I haven't trusted it, and I too usually fill up when it hits the 1/4 of a tank.

Right now it's sitting on 1/4 tank, but I'll keep driving it till the weekend as petrol has hit $1.40 again in Melbourne (always seems to hit that figure every Wednesday evening, then stays till the weekend... )

 

[beeks]

Yeah.. Before the Commodore I used to drive a Corolla everywhere.. And a Statesman..

I never let the tank get below 1/4.. Occasionally it did get below, but I'd keep an eye on it..

I don't understand why some people regularly run their car til the fuel light comes on or the guage gets below empty..

Granted,in some situations it's unavoidable.But what it all boils down to is you should never let your car run out of juice and you have taken appropriate steps to ensure this never happens,well done.

 

[sparky]

I nearly always run my wagon down to 0km to go and i've always got atleast 10lts left in the tank so i know i've got a little back up if needed.

It took me a little while to work this out though, i always used to think that my tank was smaller than 75lt or was dented, but if i've been pushing it a little harder and i think i might run out i always carry the little 5lt jerry.

 

[mikemutlow]

I agree you don't want ever to run out and there really isn't any sense in pushing the boundaries on this.
However, it really is a case of knowing your own car and understanding its particular querks. I have to fill up at least once a week and nearly always run to 0 on the DTE gauge as I know that there is always at least 10 litres left in the tank. What I have come to rely on and use to reassure me is the Litres Used readout, which seems to be much more accurate - never been more than 1 or 2 litres out.This figure must be calculated by the computer based on the actual fuel delivered through the injectors and does not rely on the fuel tank sender in any way. Since I always fill the tank right up, I can easily tell what is actually left by deducting the fuel used from the 75 litres which I know was definately in there to start with.
This week, for example, the red light came on and I travelled approx 40 kms before the DTE went to 0 and then I travelled another 60 kms before filling up. I could only get 69.5 litres in even then. At all times, however, I knew exactly (well almost) what I had left based on the Litres Used reading.

 

[ciaranvt]

bit of a prob with your theory bro. I fill the living crap out of my tank. really really really fill it! It doesnt drop below full for nearly 100ks of CITY driving. When I use the digital fuel readout it doesnt move from 75litres until the fuel guage begins to move.

so the theory of that it calculates fuel delivered thru the injectors goes against your theory..

 

[milno]

My DTE is right on the money, it will vary around town as you need a constant accurate speed over a few kms for it to work out the math.
On the highway it is 100% around town it varies.

Test it drive on 80 for 2 mins then on 100 for 2 mins you will find you get less DTE on 100 cause the engine is working at higher revs! Similar to around town when you are using revs to pull through the gears there for concuming up to 12-13litres per 100km

 

[VSIIBerlinaL67]

when you say the dte is goin all over the place its cause its reading how far your puttin your foot down more down gonna get less ks , i find when i give it a bit the dte goes really low but then i granny it for 10 mins and it goes higher
the dte is calculated with how your drivin and the amount of fuel

 

[mikemutlow]

ciaranvt - I'm Ok with you challenging my theory, however, I think you have misunderstood which readout I am referring to since you said "the readout doesn't move from 75 litres...". This suggests that you are talking about the 'Litres left' digital readout which is just a numerical display from the tank sender signal ie has the same discrepancies as the fuel gauge.
What I was talking about was the 'Litres Used' readout which starts off at '0 litres' (assuming you zero the display when you fill up);not sure if all models have this facility though. This readout can also be calibrated by using the special functions feature if you know what the percentage error between actual litres used (ie how much you actually put in the tank, based on several fill ups ) and the calculated figure on the display. This way you can be sure that the readout is pretty well spot on.

 

[gogoboygareth]

Hi guys,

Since my last post about how inaccurate my guage is - I've run out of fuel. Twice.

One was a few weeks ago, I had 1/8 tank left (according to the gauge - DTE was reading about 80kms) and was actually driving to the local petrol station (thank god!). I bought a 20 litre jerry can, filled it up and used half of it in the tank (leaving the rest in the boot).

My girlfriend took my car to Bendigo this weekend, and she called me around a half hour ago - the car died AGAIN. The engine simply stopped while driving, with the battery light on. The car would start and idle for a few seconds, with the idle becoming rougher and rougher, chugging then stopping (all within 5 seconds).

The gauge was apparently showing 1/4 tank with the DTE of 270km.

After putting the remaining 10 litres from the jerry can into the car, she called back and said it's purring along nicely again.

I have the feeling either my gauge is totally stuffed, I have too much sludge in the tank, or my fuel pump is playing up (but then again it always starts again nicely once I put 10 litres in)....

Any ideas????

- Gareth

 

[randomroen]

Letting your car run empty until it just stalls isn't a very good idea. Someone posted something earlier saying that by running it down till empty causes dirt and sludge to get pumped into your engine, not only that, but if you run your tank down until its completely empty can also damage the fuel pump. The fuel pump relies on fuel circulation, and if you keep letting it run down to empty you run the risk of burning out your pump.