172 cup using LOADS of fuel....

[jack_kemp]

My car seems to be using a huge amount of fuel.....

My speedo sensor broke last week, so could this be why?

The trip says that I'm doing 8mpg.... but I'm guessing this is due to the speedo not working. I did a little test on it over the last couple of days, and it's doing about 16 / 17 mpg, maybe less (my fuel guage seems to fluctuate a lot). I've only been to work and back so haven't been driving quickly at all, just normal road driving.

 

[jack_kemp]

I tried this again, it's actually more like 11 / 12mpg.

Has nobody else had this? It was averaging 32.7mpg until this week... Somebody must know why!

 

[quik99]

Thats extreme! anyone would think you drive purely on a track lol.

If i were you i would get it on a diagnostics machine to see if there is any recorded fault. Fixing the speed sensor would be a good start but i wouldnt know if that is linked to the problem, it seems unlikely. Has it been like it ever since the sensor broke? if so then fix it and see what happens! Only other thing i can think of is a fuel leak/split fuel pipe? does the engine splutter or anything (ie its over fueling).

 

[sideways danny]

speedo sensor fault can cause some very odd issues that you wouldn't expect

 

[Dave.]

seriously knackered upstream lambda... ???

 

[RenaultSport]

I did find that changing the thermostat in mine improved the MPG, the stat must have been funny for a while causing high fuel usage. Can't say I had it in single figures though!

 

[jack_kemp]

It doesn't feel like it's over fueling, engine runs clean and doesn't seem to have lost any power. Ive been driving super nice while I've been measuring, but even on my motorway journey to work its barely touching double figures. There's no smell of fuel and no deposits on the floor in the mornings... I'm really confused.

The speedo was intermittent for a week, died completely about 4-5 days ago. It's been intermittent since I got the car, but fuel consumption was fine when I got it. Averaged nearly 40mpg on the way back from notts when I bought it.

Where can I get a speed sensor from the quickest?
I need to fix it asap, it's cost me £75 in fuel in a week, done 170miles.

I've got the car booked in for a cambelt at rentech next week so I'll get them to stick it on the diagnostic. Just wanted to get it fixed sooner than that really...

 

[integraleSte]

My speedo sensor is also intermittent and I have noticed that on journeys where it packs up the average mpg on the trip drops by quite a lot. I put it down to the car thinking that it wasn't moving yet pulling 4k rpm so the fuel economy would be bad in that instance. I need to replace the speedo sensor in the gearbox but it's on a list with many other things that need doing to the car.

 

[jack_kemp]

My speedo sensor is also intermittent and I have noticed that on journeys where it packs up the average mpg on the trip drops by quite a lot. I put it down to the car thinking that it wasn't moving yet pulling 4k rpm so the fuel economy would be bad in that instance. I need to replace the speedo sensor in the gearbox but it's on a list with many other things that need doing to the car.

This was my thinking... Permanently running a rich mixture.

Cheers everyone, I'll buy a new sensor and see how it goes.

Is renault the best place to get these from? I'm assuming it's a straight forward fit?

 

[sideways danny]

renault for the sensor, easy enough to fit

 

[midge]

on a cup the speed sensor isnt in the box isit ?

 

[jack_kemp]

Just rang Renault, they tell me it's only £19.89 + VAT. I'm guessing it's so cheap as it's a cup? Or is that standard price?

I know it's not mounted in the gearbox on the cup, so.... where is it? If I can find the thing, I'm sure it's not difficult to do....

 

[jack_kemp]

seriously knackered upstream lambda... ???

Dave... my engine emission warning light has just come on too..... so you may just be on to something here.

 

[Dave.]

That's what I'd have a look at only replace it with a Bosch one!

 

[jack_kemp]

That's what I'd have a look at only replace it with a Bosch one!

Thanks mate.... I'll get one of these too.

Don't suppose you know where the speed sensor is on a cup do you?

 

[Dave.]

i think it runs off the abs... but i know other's run it off the TDC but im not certain, funny things these renaults!

 

[jack_kemp]

Not on the cup, it doesn't have ABS

Not to worry, I've just asked Rentech to do it while they're doing my belts.

 

[renclio182]

cups run a gearbox sensor

 

[jack_davey]

Bring it round for a diagnostic check if you like mate, I'm round the corner from Crawley

 

[jack_kemp]

Bring it round for a diagnostic check if you like mate, I'm round the corner from Crawley

That sounds ideal mate, where in Surrey are you?

 

[Daniel]

When you say you have measured what mpg you're getting, how are you doing this?

The only 'proper' way of doing it, is to fill the car to the brim, drive until you run out and calculate.

So for example fill your tank. Say your tank is 50 Litres, (add another 2 for the filler neck and pipework) So thats 52 Litres of fuel at £1.17p per litre. Reset the trip computer, Drive until the car runs out. Calculate.

Its no good working off putting a tenner in and judging it on what the gague is saying. Thats a lottery.

 

[jack_kemp]

When you say you have measured what mpg you're getting, how are you doing this?

The only 'proper' way of doing it, is to fill the car to the brim, drive until you run out and calculate.

So for example fill your tank. Say your tank is 50 Litres, (add another 2 for the filler neck and pipework) So thats 52 Litres of fuel at £1.17p per litre. Reset the trip computer, Drive until the car runs out. Calculate.

Its no good working off putting a tenner in and judging it on what the gague is saying. Thats a lottery.

I didn't want to run it completely empty, just to avoid any possible damage. So I filled up a can with 2 gallons, ran the car until the fuel light came on, then put the fuel out of the can in, reset the trip and ran it until the light came on. I guessed this wasn't very accurate, so I repeated it 3 times and took an average.

Best I could do Really.

 

[darko18781]

I've been having pretty much the same problem mate (ie speedo gets a bit erratic and then dies and the mpg drops to the teens). Let me know if the gearbox sensor fixes it. Cheers.

 

[jenic]

Fill it until it clicks once.

Drive at least 100 miles.

Return to same pump and fill until it clicks once.

The amount you filled up the second time is what you used to do the amount of miles you did. Calculate from these figures.

Thats the best way to work out true MPG imo

 

[jack_kemp]

It's not really worth me doing it again.... My method might not be the most accurate, but it's not that flawed that it would give me 12mpg!