Weird dash behaviour/trip comp

[woott]

Hi,
At traffic lights car stalled on me,re started no probs but trip and fuel gauge showed about 70 miles less??
it did show 90 miles to go but re-showed 20 miles left and low fuel light and beeped to tell me.

Wierd.
Coog v6 x-pack.

 

[Quicksilver]

The fuel computers are notoriously inaccurate, especially in the bottom 1/4 of the tank.

 

[woott]

yeah possibly.
ill bung a tenner in it to see how far the fuel gauge goes up.it did have £15 in it but now only registers 20 miles left??
deffo electrical.

 

[Quicksilver]

The 'drop' usually happens overnight from stopping it one day to starting it the next; your stalling mimicked this.
It's the computer 'catching-up' with itself and compensating for the taper towards the bottom of the tank.
If you brim the tank, zero the trip and take a note of the 'miles to empty' and then compare the two values every 50 or 100 miles you'll get some idea as to how inaccurate they are.

 

[Mako]

The fuel gauge and the computer work from the same source - the float in the tank. The difference between them is that the fuel gauge knows what's there, but the computer knows how you drive.

If your gauge is correct but your computer is not, trust the gauge and reset the ECU. If both are wrong, suspect the float.

But from your description it sounds like the computer is scrambled. It's not hard to confuse it at the best of times to be honest - Mrs. Mako's Mondy would happily report -20 miles in the tank when it had plenty left. Tiger will say I've only got 100 miles left when I have 200 because of my short commute.

Disonnect the battery or pull the ECU fuse to reset. Then fill the car and work out for yourself what sort of mileage you can get.

 

[backseateducation]

Mine does that if I stall it with less than 1/2 a tank. It usually happens when I forget I'm not driving a bus and neglect to select the correct gear
Give it a few miles and it sorts itself out

 

[woott]

cheers guys will give it a try.
my mistake for leaving it in 3rd gear,dork.

 

[Arkady001]

Never trust the trip computer once the fuel warning light comes on. I went from 50 miles remaining to zero in 35 miles even though I was babying it... With predictable results... As in: walking the last 2 miles to the Tesco filling station I was aiming for.

 

[banhim]

Our Astra just used to give up at about 100 miles and just exclaim !REFUEL! on the dash display.

The MX5 facinates me, they have a woefully pessimistic fuel gauge, it'll happily run for fifty or so miles on hard empty.

 

[Procomm]

If you decide to pull the ECU fuse, disconnect the battery first, removing the ECU fuse with battery connected can result in an electrical spike going to your ecu which will kill it.