Waste of Petrol?

Seanohea · 16-12-2009 6:19pm #1

Just a quick question here if someone could please help.

Over the past 2 months i've noticed my car using up far more petrol than normal, 28 miles to the gallon, would anyone know what the problem could be?
I'm bringing the car to a mechanic tomorrow. I drive a 2000 opel astra 1.4 hatchback

CamperMan · 16-12-2009 6:20pm

Seanohea wrote: »

Just a quick question here if someone could please help.

Over the past 2 months i've noticed my car using up far more petrol than normal, 28 miles to the gallon, would anyone know what the problem could be?
I'm bringing the car to a mechanic tomorrow. I drive a 2000 opel astra 1.4 hatchback

what's your driving style like?, do you fast?

Seanohea · 16-12-2009 6:24pm

No, not really, i'm 27, i'm relaxed nowadays. I just definetley know i used to get way more milage in the past

TestTransmission · 16-12-2009 6:25pm

When was it last service?Is the pressure correct in your tyres?

mastermind2005 · 16-12-2009 6:28pm

Tires are a big factor.

also check airfliter isnt blocked with a leaf or somthing and also change or clean your spark plugs.

Seanohea · 16-12-2009 6:32pm

last serviced in march, its due a service, but that cant be all it is. I've been due a service in the past and petrol has gone as quick as this. Checked the tyres this morning, theyre all good

mastermind2005 · 16-12-2009 6:34pm

you need to bring the car to the petrol startion and make sure they are close to max pressure.

Prenderb · 16-12-2009 6:42pm

Some suggestions:
1: A fuel leak somewhere, though you'd probably notice this on your driveway.
2: Problem with the fuel injection system.
3: When you calculated your mpg you forgot to carry the one - did you check your calc?
4: A change in driving conditions in the last 2 months, from motorway driving to urban driving or a similar change like that, or long trips to shorter trips
5: someone else mentioned checking your tyre pressures are good, which you did
6: Carrying more weight than you used to in the car?

What did you get 2 months ago? I mean to ask, what was your mpg in the days before it was 28?

Seanohea · 16-12-2009 6:43pm

mastermind2005 wrote: »

you need to bring the car to the petrol startion and make sure they are close to max pressure.

I did that this morning so that cant be the problem, tyres are fine.

Seanohea · 16-12-2009 6:50pm

Prenderb wrote: »

Some suggestions:
1: A fuel leak somewhere, though you'd probably notice this on your driveway.
2: Problem with the fuel injection system.
3: When you calculated your mpg you forgot to carry the one - did you check your calc?
4: A change in driving conditions in the last 2 months, from motorway driving to urban driving or a similar change like that, or long trips to shorter trips
5: someone else mentioned checking your tyre pressures are good, which you did
6: Carrying more weight than you used to in the car?

What did you get 2 months ago? I mean to ask, what was your mpg in the days before it was 28?

Mpg was about 45 per gallon. I said 2 months ago because thats when i noticed the petrol consumption going downhill, nothing out of the ordinary happened.
No leak that i can see. No more weight than before. Not doing as much driving as before

John Mason · 16-12-2009 7:13pm

well according to top gear using your heaters uses petrol :rolleyes:

TestTransmission · 16-12-2009 7:17pm

Seanohea wrote: »

Mpg was about 45 per gallon. I said 2 months ago because thats when i noticed the petrol consumption going downhill, nothing out of the ordinary happened.
No leak that i can see. No more weight than before. Not doing as much driving as before

I think 45mpg is a bit over optimistic tbh

daveharnett · 16-12-2009 7:19pm

If tyres, filters and plugs are all good, then i think the next port of call would be the egr valve?

langdang · 16-12-2009 7:31pm

Seanohea wrote: »

Mpg was about 45 per gallon.

Are you sure, seems a bit high?

Seanohea wrote: »

Not doing as much driving as before

Doing a lot of short hops in cold weather? Were your higher mpg figures from longer trips in less cold weather?

Does your car get warmed up in a normal time period?
I had a car with the thermostat stuck open during a cold spell, thing spent ages running rich and piddled through fuel until it got properly warmed up.
Lot's of short hops would leave you in the same situation...

Is the car idling ok once warmed up?
Does it sound a bit odd when idling or is there a noticeable juddajuddajudda vibration if you put your hand on the bonnet? There will always be some vibration, but if there is any slight misfire going on then you'd probably notice the extra. Could be a fuel/air mixture problem or timing/spark issue.

Your mechanic should be able to figure these out handy enough if you can't.

Have you got the rear window demister permanently on?
Wouldn't account for all the loss in mpg, but it does make a difference?

Prenderb · 16-12-2009 7:33pm

I also think 45 might be a bit optimistic. It's a 9 year old petrol, so I'd say 45 would be hard to reach.

This guy has an mpg of 29.7 on average, similar car to yours. Maybe you've got nothing to worry about.

mickdw · 16-12-2009 9:19pm

daveharnett wrote: »

If tyres, filters and plugs are all good, then i think the next port of call would be the egr valve?

Would have to agree with that

zilog_jones · 16-12-2009 9:21pm

Prenderb wrote: »

This guy has an mpg of 29.7 on average, similar car to yours. Maybe you've got nothing to worry about.

That's 29.7 US MPG, 35.1 imperial.

sleepysniper · 16-12-2009 9:45pm

It'd be no harm to check the MAF sensor. If its faulty/dirty it may cause the ECU to inject too much fuel into the chamber as it cant measure the correct amount of air coming in.

Prenderb · 16-12-2009 9:46pm

Thanks for pointing that out...back to the pondering couch.

Interesting site, btw, innit? you can change from US to UK and Metric in the top left corner.

This has me thinking though - what figures did the OP use for his calculations?

numorouno · 16-12-2009 10:56pm

Prenderb wrote: »

I also think 45 might be a bit optimistic. It's a 9 year old petrol, so I'd say 45 would be hard to reach.

This guy has an mpg of 29.7 on average, similar car to yours. Maybe you've got nothing to worry about.

ive a 2000 toyota corolla liftback and im averaging 43mpg and often as high as 47. i had a similar drop in mpg a while back and it was due to a faulty fuel input or injector.was down as far as 27 for 2 fills and back up again after it was replaced

Nozebleed · 16-12-2009 11:11pm

a friend of mine said the same thing to me the other day...his Peugeot 306 really started to guzzle and his mechanic said the catalytic converter was busted. causing the car to use up much more petrol than it should.

zilog_jones · 17-12-2009 12:10am

Prenderb wrote: »

Thanks for pointing that out...back to the pondering couch.

Interesting site, btw, innit? you can change from US to UK and Metric in the top left corner.

Yeah it is an interesting site, thanks for the link. It's a bit US-centric though, but at least they've made it accomodate for our silly half-metric world of buying fuel in litres and measuring fuel economy in MPG

Seanohea · 17-12-2009 2:25am

Thanks for the help and info guys, really appreciated. I'll see what happens tomorrow (later today)

Prenderb · 20-12-2009 12:18pm

Any resolution, seanohea?

bongi69 · 20-12-2009 12:47pm

I've had this problem recently too.
Turned out to be a faulty oxygen sensor, which was found out when the engine management light came on.
Once it was replaced, consumption was back to normal

Waste of Petrol?

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