Astra serious heavy on juice

canhefixit

I have an 05 astra h 1.4 which is only returning about 25mpg, it recently threw up eml for maf so checked for any leaks an none so replaced sensor now light off but made no diff at all to fuel consumption

Now the tired are proper inflated, there's not any excess weight in car, car is well serviced but it's just drinking the petrol to the point were I can't afford to even use it and when you driving it u can see the petrol gauge go down

Now the car is in perfect condition and a lovely car to drive and I would like to be able to fix something on it to make it more fuel efficient otherwise it has to go

So any suggestion people?

Cheers

Jesus.

Maybe someone drilled a hole in the tank?

Foxhole Norman

By replacing the sensor do you mean you replaced the MAF itself? A faulty MAF can cause the car to run rich in fuel to compensate for the incorrect information it would be getting from the MAF. Does the car idle rough at all?

biko

Does exhaust gases smell rich?

dieselbug

canhefixit wrote: »

I have an 05 astra h 1.4 which is only returning about 25mpg, it recently threw up eml for maf so checked for any leaks an none so replaced sensor now light off but made no diff at all to fuel consumption.

Cheers

Was this a brand new genuine maf from Opel?

bazz26

How are you calculating the mpg?

flintash

i've read somewhere that old and tired O2 mess up fuel ratios aswell. i had 87 escort that did 27m/gal regardless city or highway driving. couldn't figure out and left it that way...

Chemical Byrne

Get an ELM327 or something on it see are there any other fault codes in the system that might guide you in the right direction. Also have a look at the parameters from the different sensors to see if there's any off the wall readings that might be throwing out the fuel metering or ignition.
I'd second investigating the O2 sensor(s). They operate in a very harsh environment and have a huge input into how much fuel is injected.

As an initial low tech but effective check you could "read the plugs". If they are fouled with black carbon you can be sure the engine is overfuelling. Google reading plugs to get handle on how this technique is applied.

Atlantic Dawn

25mpg may be normal if you are driving in urban short drive conditions.

jca

Atlantic Dawn wrote: »

25mpg may be normal if you are driving in urban short drive conditions.

Very true, could be worse in some cases.

visual

My 2.5 litre car would be down in mid twenties with city driving but the astra should be better than 25 mpg

have the codes read their may be another issue

canhefixit

Foxhole Norman wrote: »

By replacing the sensor do you mean you replaced the MAF itself? A faulty MAF can cause the car to run rich in fuel to compensate for the incorrect information it would be getting from the MAF. Does the car idle rough at all?

Replaced with a genuine Opel part and car Dosent run rough at all it runs perfect to be honest

canhefixit

biko wrote: »

Does exhaust gases smell rich?

I need to double check this one as I'm not sure tbh, but I don't think so as I think I would of picked up in it big I'll defo check it out, what would you suggest if there was?

canhefixit

bazz26 wrote: »

How are you calculating the mpg?

Used a formula on another site where I filled tank, drove till empty then inputted the tank size by cost by litre by miles covered actually gave me 24 mpg which is horrific

cletus

Easiest way to calculate is brim, drive, brim, distance divided by amount. Its best to do it a number of times to work out a rough average. If you do it at every film, you start to know what to expect, roughly, for a quarter tnk, half tank etc

George Dalton

What kind of driving do you do?

George Dalton

canhefixit wrote: »

Used a formula on another site where I filled tank, drove till empty then inputted the tank size by cost by litre by miles covered actually gave me 24 mpg which is horrific

That's not accurate because you calculated the distance based on the full size of the tank but you didn't use all the fuel in the tank. In fact you have no idea how much fuel was left in the tank.

As the other poster already stated, the only accurate way to test MPG is to fill the tank, reset the trip meter, drive for xxx miles, then fill again and you know exactly how much fuel you have used to cover xxx miles.

Chemical Byrne

Stick an ELM 327 on it and it will give you the MPG also. I've got a bluetooth one plugged into my car permanently. I can get every sort of gauge and readout on my phone.

A 1.4 astra should be well into the 30s or even with town driving. I have a 1.5 Almera and it's averaging 48MPG with about a 50/50 mix of city and open road. But then I don't have a lead boot and tend to drive very easy.

canhefixit

When I brimed car I did drive it till it was almost empty, I've done this a few times and get almost the same mileage
My driving is mainly national roads very little town driving, I drive it as easy as I can to get the most out of the petrol coz if I floor it on motorway the fuel needle nearly drops like a stone!
I've checked for leaks, I've serviced car, tyres are right pressure, no eml codes, no knocks or bangs, no petrol fumes in exhaust
Can't get my head around why it's so heavy on petrol

Jesus.

Jim will fix it, no matter what way you slice it you still haven't calculated the MPG correctly so you really do not know what it is!

Francie Barrett

cletus wrote: »

Easiest way to calculate is brim, drive, brim, distance divided by amount. Its best to do it a number of times to work out a rough average. If you do it at every film, you start to know what to expect, roughly, for a quarter tnk, half tank etc

This is how to measure fuel consumption.

As a matter of interest, what mileage are you getting from your technique?

jca

Jesus. wrote: »

Jim will fix it, no matter what way you slice it you still haven't calculated the MPG correctly so you really do not know what it is!

He has calculated the mpg correctly.

jca

canhefixit wrote: »

When I brimed car I did drive it till it was almost empty, I've done this a few times and get almost the same mileage
My driving is mainly national roads very little town driving, I drive it as easy as I can to get the most out of the petrol coz if I floor it on motorway the fuel needle nearly drops like a stone!
I've checked for leaks, I've serviced car, tyres are right pressure, no eml codes, no knocks or bangs, no petrol fumes in exhaust
Can't get my head around why it's so heavy on petrol

Has it always been heavy on juice or did it suddenly start getting thirsty?

cletus

jca wrote: »

He has calculated the mpg correctly.

Not really, he hasn't taken account of the amount of fuel used for any given distance.

Driving till nearly empty is not the same as noting the distance and dividing by the volume.

Having said that, once you have done the calculations a number of times, you begin to know what sort of mileage you'll get by the guage, but its not an accurate way to measure

vandriver

When you empty the tank,how many km have you done?

canhefixit

vandriver wrote: »

When you empty the tank,how many km have you done?

Ok so car is way in the red again this morning and out of a 50l fill I got 260 miles
Something isn't right with car there is no way car should be doing about 24mpg
I drive easy, car is driven on national/motorway roads I won't even dare floor it knowing what it would cost me!

punisher5112

What gear are you using and don't let the engine struggle.

I have a 1.6 and its not far off as thirsty as my Octavia vRS.

If you are up and down the gears constantly or up down hill roads car will use more fuel.
Where are you filling up?

Have you changed spark plugs,air filter, fuel filter.

Have you thought of possible cat problem or blow in exhaust.

canhefixit

punisher5112 wrote: »

What gear are you using and don't let the engine struggle.

I have a 1.6 and its not far off as thirsty as my Octavia vRS.

If you are up and down the gears constantly or up down hill roads car will use more fuel.
Where are you filling up?

Have you changed spark plugs,air filter, fuel filter.

Have you thought of possible cat problem or blow in exhaust.

I honestly drive as easy as I can in the car I consciencely keep it below 3000rpm when driving
Car was recently fully serviced with new plugs, oil an filter, air filter etc
There isn't any blows on exhaust like the car drives and sounds like notin wrong but it's just drinking petrol

dieselbug

If the car is returning poor mpg as it seems to be. There are lots of things that can be checked to see if the engine is feulling correctly or not.

You need to get it somewhere that will check things like fuel trims idle and loaded, emissions, o2 activity, valve timing etc and someone that knows what they are looking at.

Couple of hours would tell a lot and could be money well spent.

jca

canhefixit wrote: »

Ok so car is way in the red again this morning and out of a 50l fill I got 260 miles
Something isn't right with car there is no way car should be doing about 24mpg
I drive easy, car is driven on national/motorway roads I won't even dare floor it knowing what it would cost me!

Taking a guess the the petrol cost 134.9 per litre that's a shade over 31 mpg. I mistakenly thought you were calculating fuel consumption on a full tank basis. Trying to do it on 50 here and 30 there is very inaccurate.

vandriver

jca wrote: »

Taking a guess the the petrol cost 134.9 per litre that's a shade over 31 mpg. I mistakenly thought you were calculating fuel consumption on a full tank basis. Trying to do it on 50 here and 30 there is very inaccurate.

It says 50 litres not 50 Euros!

jca

vandriver wrote: »

It says 50 litres not 50 Euros!

Ooops it does too...

Jonty

When you go for a drive for a bit, say 10 miles. Get out and just check the rims of the tyres for heat. Excessive hot rims would indicate a seized caliper.

A seized caliper would make the car hard on juice

Jesus.

JCA you're all over the shop on this one brother

jca

canhefixit wrote: »

I honestly drive as easy as I can in the car I consciencely keep it below 3000rpm when driving
Car was recently fully serviced with new plugs, oil an filter, air filter etc
There isn't any blows on exhaust like the car drives and sounds like notin wrong but it's just drinking petrol

We had a 1.6 in the job and it struggled to get into the 30's and it did a a 50/50 mix of town and long journeys. Is it getting up to temperature quickly? and is the gauge sitting in the middle all the time? The one we had went through a spate of low 20's mpg and it turned out to be a failed/lazy thermostat.

jca

Jesus. wrote: »

JCA you're all over the shop on this one brother

Bud - wei - ser.

Cork981

My 1.6 2008 model barely hits 29mpg about 9.7l/100km.

Very thirsty car in my opinion. Produces 115bhp which is high enough for a naturally aspirated 1.6 petrol.

Jesus.

That is very thirsty Cork. You should be getting late 30's mixed in a 1.6 smallish car.

I've a 1.6 heavier, older car which returns on average 38-39mpg mixed (brim method, not trip com).

Cork981

Jesus. wrote: »

That is very thirsty Cork. You should be getting late 30's mixed in a 1.6 smallish car.

I've a 1.6 heavier, older car which returns on average 38-39mpg mixed (brim method, not trip com).

I'm basing that off my trip but it's defnitely very very thirsty.

What does your trip report and how actually accurate are they ?

Jesus.

In my experience the trip coms always overestimate by about 2-4 mpg. So you're probably getting even less than you think in reality :eek:

Cork981

Jesus. wrote: »

In my experience the trip coms always overestimate by about 2-4 mpg. So you're probably getting even less than you think in reality :eek:

Great I was hoping they underestimate and I was being a drama queen !!!

Planning to upgrade to something like this next month anyway

http://m.carsireland.ie/detail.php?ad_id=1175191&r=s.php%3Fm%3D63%26o%3D868%26i%3D80000%26ot%3Dm%26nn%3D11%26yn%3D2011%26g%3D0

Chemical Byrne

Jesus. wrote: »

In my experience the trip coms always overestimate by about 2-4 mpg. So you're probably getting even less than you think in reality :eek:

Perhaps that is because the speedos overestimate speed?
But to does the ECU actaully measure the actual speed and just display a slightly greater speed on the speedo or is the sensor hardware set up to give a falsely high speed reading.

H3llR4iser

canhefixit wrote: »

I have an 05 astra h 1.4 which is only returning about 25mpg, it recently threw up eml for maf so checked for any leaks an none so replaced sensor now light off but made no diff at all to fuel consumption

You still haven't said what kind of driving you do, which is what makes all the difference really. The worst possible scenario is the one where you constantly drive between traffic lights - like red, stop, wait, start, get up to speed and 500 meters later, another red - rinse and repeat. Even worse than bumper-to-bumper, stop/start traffic in certain circumstances.

I used to get similar figures on a 1.4 Megane on the home-work trip, while it went above the 40 mark while driving on open roads.

ourheritage

I'd bring it to your mechanic. There's definitely something wrong. Also next you take it out, use the gears as little as possible. My mother does that with her 1.8, and she has to fill it very occasionally, and that's from going round town.

Chemical Byrne

ourheritage wrote: »

I'd bring it to your mechanic. There's definitely something wrong. Also next you take it out, use the gears as little as possible. My mother does that with her 1.8, and she has to fill it very occasionally, and that's from going round town.

Me too. Reading the road right makes enormous difference in efficient town driving - for example don't accelerate towards a traffic light you know is gonna be red by the time you reach it and you have to break. Judge it so that you can trundle along and get there when it's green and not have to stop. Same goes for moving along in queues, harsh start/stop keepin up to the fella in front gobbles up the juice. Just ease it along in 1st and let a bit of a bufffer gap between you and the car in front. Fúck the knob behind you in the BMW, he's not gonna get there any quicker anyway.

I do this and get like 40+ out of a 1.5 Almera in the town and 48 combined over the last 10000 mls

visual

Chemical Byrne wrote: »

Me too. Reading the road right makes enormous difference in efficient town driving - for example don't accelerate towards a traffic light you know is gonna be red by the time you reach it and you have to break. Judge it so that you can trundle along and get there when it's green and not have to stop. Same goes for moving along in queues, harsh start/stop keepin up to the fella in front gobbles up the juice. Just ease it along in 1st and let a bit of a bufffer gap between you and the car in front. Fúck the knob behind you in the BMW, he's not gonna get there any quicker anyway.

I do this and get like 40+ out of a 1.5 Almera in the town and 48 combined over the last 10000 mls

The official MPG for your box is 42 mpg..
And doodling along holding up traffic won't fix poor mpg.

jca

Chemical Byrne wrote: »

Me too. Reading the road right makes enormous difference in efficient town driving - for example don't accelerate towards a traffic light you know is gonna be red by the time you reach it and you have to break. Judge it so that you can trundle along and get there when it's green and not have to stop. Same goes for moving along in queues, harsh start/stop keepin up to the fella in front gobbles up the juice. Just ease it along in 1st and let a bit of a bufffer gap between you and the car in front. Fúck the knob behind you in the BMW, he's not gonna get there any quicker anyway.

I do this and get like 40+ out of a 1.5 Almera in the town and 48 combined over the last 10000 mls

48 mpg from an almera? Do you use the accelerator at all? According to the description of your town driving you'd be better off cycling...

Jesus.

Chemical Byrne's town driving style is spot on but there's no way in hell he's getting a real 48mpg mixed driving from an Almera, still less 40+ in town!!!

canhefixit

My driving is mainly national roads and motorway very little town with start/stop driving, i drive the car as easy as possible and get up the gears quick to not work the car to much, i cant say for sure if it gets up to temp quick or not as it has no temp gauge on dash but dosent take long for heat to come from fan, jacked up car to check tyres and they still perfect as they only new 300 miles ago plus i spun them and they all moving freely so can rule out sticking caliper or that

Has to be something wrong with it as it cant consume this much petrol normally

TheDoc

I've a 00 Astra G, and I'd sympathise with the OP. I havn't ever gone about calculating the actual MPG, but I know it's utterly rubbish.

Car is in lovely condition, serviced every year and nothing major has happened in over a decade. I do mostly my daily commute which is Swords -> M1 - M50 -> Park West, and then the other direction home.

Some sporadic short distance stuff in between.

Absolutely guzzles petrol something fierce. Obviously as its my first car don't have anything to immediately compare it to, but just from people yapping it seems that its heavy on the juice.