i30 Owners Club

FUEL ISSUES & ECONOMY => DIESEL => Topic started by: ryaz11 on April 26, 2011, 06:23:50

Title: Very poor fuel economy
Post by: ryaz11 on April 26, 2011, 06:23:50
 :disapp: :disapp:
Hey guys, So i have had my car for 6 weeks and i have done abit over 2000 k's (best car mind you)

But at the moment i still am getting very poor fuel economy 8.9 litres. I have the sx diesel and can only get 600km.
Will this improve? it is very fustrating as i fill the car up everyweek and with 154.9 a litres here in melbourne for diesel its not cheap..

Thanks guys
Title: Re: Very poor fuel economy
Post by: ryaz11 on April 26, 2011, 06:30:20
sorry i must say that i do 70% day to day driving as in to the shops and back and the rest is 30% is freeway 90-100
Title: Re: Very poor fuel economy
Post by: AlanHo on April 26, 2011, 06:57:47
That is very poor fuel economy - even for town driving.

Are your tyre pressures correct?

Are you idling the car before setting off and after completing a journey?

Have you asked the dealer to check the car under warranty.  I would.
Title: Re: Very poor fuel economy
Post by: ryaz11 on April 26, 2011, 07:08:33
Hey AlanHo
No i dont idel i just take off same as when i get home.

Yes i have the tyre pressure at 32psi is that right?


I thought maybe it might get better once the car gets abit over 10,000kms ?
Title: Re: Very poor fuel economy
Post by: Dazzler on April 26, 2011, 07:41:28
Hi Ryan..

I suspected it was an Auto (confirmed that by looking at your introductory post)  :goodjob:

It will improve but the Diesel Auto is certainly way more thirsty than the Manual version by all accounts on here..

8.9 is really  :disapp: Other Auto owners have been complaining of figures around 8.0  :blubber:

In this thread some are getting considerably better...

https://www.i30ownersclub.com/forum/index.php?topic=7246.0 (https://www.i30ownersclub.com/forum/index.php?topic=7246.0)

Title: Re: Very poor fuel economy
Post by: AlanHo on April 26, 2011, 07:43:29
I have my tyre pressures set at 36 psi all round.

My manual car has done 5000 miles. Recent fuel economy - using the Air Con on all the time - has been

Short trips about town - 6.7 L/100 km
Motorway journeys - 5.6 L/100 km

I tend to drive the car fairly gently - never accelerate hard unless I have to quickly overtake and I cruise at speed limits. When the car was new - economy was not quite as good - but nowhere near your figure. 

The Hyundai brochure lists the 1.6 auto combined fuel consumption at 26% higher than the manual. Having said that I cannot get close to the brochure combined figure of 4.5 for the manual.

Just a thought - how are you measuring your fuel economy. Are you quoting the computer display or are you doing brim to brim calculations - being careful to brim the tank fully each time?
Title: Re: Very poor fuel economy
Post by: ryaz11 on April 26, 2011, 08:42:43
Hey guys

Thanks for your feedback. Yes i am doing brim to brim and always to the top. Yes it is auto so i guess thats why its very high.

Yes i dont speed much accelerate slowly unless im overtaking maybe i should try 36psi?
Title: Re: Very poor fuel economy
Post by: Dazzler on April 26, 2011, 11:09:31
Something doesn't seem right Ryan...

 I would take it in to the dealer ask ask then to check the ECU to make sure it is set correctly.. Or just a thought (can't do any harm) Disconnect the battery overnight which is supposed to reset the ecu and see if that makes nay difference to your next few fills.

You could also try driving the car like a manual for a few days. Changing at what you see as the ideal changing points as a couple of members say the auto will learn your driving style that way (and it might help the economy) :idea:

Title: Re: Very poor fuel economy
Post by: rustynutz on April 26, 2011, 11:14:34

You could also try driving the car like a manual for a few days. Changing at what you see as the ideal changing points as a couple of members say the auto will learn your driving style that way (and it might help the economy) :idea:



Worth trying what Daz suggested....
Also running your tyres with 36 psi certainly won't hurt....I'm running 40.

I know a bloke (who drove a Commodore) who would tap his slushbox back into third to "save" the brakes as he slowed for towns and traffic lights etc, you're not doing something similar are you?  :p
Title: Re: Very poor fuel economy
Post by: ryaz11 on April 26, 2011, 11:25:46
Hey there,
I just brake slowly and keep it in drive.. i will try 36psi tomorrow. i just thought being brand new and only 2000k's on the clock it might be from that. I mean i still have the plastic smell lol
Title: Re: Very poor fuel economy
Post by: rustynutz on April 26, 2011, 11:59:49
Only 2000k's on the clock certainly won't be helping.  Give it another 10,000k and it should be starting to loosen up nicely.... :whistler:

The new car smell will keep lingering....my i30 is over 13months old and you can still smell it........ :undecided:
Title: Re: Very poor fuel economy
Post by: 2i30s on April 26, 2011, 12:12:26
my car is two years old and still smells like new inside.  :razz:
Title: Re: Very poor fuel economy
Post by: rustynutz on April 26, 2011, 12:30:48
That would be the forest you have hangin' from the rear view mirror, Steve....  :P :lol:
Title: Re: Very poor fuel economy
Post by: 2i30s on April 26, 2011, 12:34:38
That would be the forest you have hangin' from the rear view mirror, Steve....  :P :lol:
that's to kill the new plastic smell.  :idea: :mrgreen:
Title: Re: Very poor fuel economy
Post by: 2i30s on April 26, 2011, 12:38:55
did your economy get better at around 10,000kms rusty?  :idea: ryaz11 may have to wait till almost then.  :neutral:
Title: Re: Very poor fuel economy
Post by: rustynutz on April 26, 2011, 12:51:18
did your economy get better at around 10,000kms rusty?  :idea: ryaz11 may have to wait till almost then.  :neutral:

Not sure about 10,000k, Steve...but as you may have noticed the other day, I'm averaging around 4.6l/100k with 19 odd thousand k's on the clock, which is pretty damn good considering the hills around my area.
Title: Re: Very poor fuel economy
Post by: 2i30s on April 26, 2011, 12:58:47
an injector pump fault could make a crdi run rich and use heaps of fuel. a factory ecu reset could be an idea.  it may even have a code error showing.  :idea:
Title: Re: Very poor fuel economy
Post by: eye30 on April 26, 2011, 13:14:02
Short trips about town - 6.7 L/100 km
Motorway journeys - 5.6 L/100 km


What's that in mpg?

At present I seem to have increased my mpg to 50 mpg, (weather warmer).

Up from 45 mpg 2 weeks ago when the weather was cooler
Title: Re: Very poor fuel economy
Post by: rustynutz on April 26, 2011, 13:21:43
About 42 and 50mpg, me thinks... :undecided:
Title: Re: Very poor fuel economy
Post by: ryaz11 on April 26, 2011, 22:30:29
So i can just take out both battery terminals to restart the ecu is that right? and leave it disconnected overnight?
It wont stuff anything up?

Thanks for all your help guys :mrgreen:
Title: Re: Very poor fuel economy
Post by: Dazzler on April 26, 2011, 22:35:08
So i can just take out both battery terminals to restart the ecu is that right? and leave it disconnected overnight?
It wont stuff anything up?

Thanks for all your help guys :mrgreen:

You only need to disconnect one of them...for half an hour or more I believe to RESET the ecu to "factory" settings...
Title: Re: Very poor fuel economy
Post by: AlanHo on April 26, 2011, 22:41:17
Apologies if I am slightly hyjacking this thread but................my i30 was fitted with a dealer installed cruise control which required them to modify the ECU settings. If I were to disconnect the battery - would it then "undo" the cruise installation?

I mention this just in case people have had similar accessories installed which required amendments to the original ECU settings.
Title: Re: Very poor fuel economy
Post by: Dazzler on April 26, 2011, 23:05:07
Apologies if I am slightly hijacking this thread but................my i30 was fitted with a dealer installed cruise control which required them to modify the ECU settings. If I were to disconnect the battery - would it then "undo" the cruise installation?

I mention this just in case people have had similar accessories installed which required amendments to the original ECU settings.

 :brilliant: question Alan.. need someone like Funky to answer that one.. Wonder if a google would shed any light on that scenario?
Title: Re: Very poor fuel economy
Post by: rustynutz on April 27, 2011, 01:57:27
So i can just take out both battery terminals to restart the ecu is that right? and leave it disconnected overnight?
It wont stuff anything up?

Thanks for all your help guys :mrgreen:

Like Daz said, you only need to remove one lead. You will lose any stations & settings you had programmed in to your radio though.
You will also need to recalibrate the torque sensor which will also reset the EPS indicator.
To do the latter, simply turn on the ignition, turn the steering wheel 3/4 of a turn left then 3/4 of a turn right, turn the ignition off and then back on.
Title: Re: Very poor fuel economy
Post by: Pip on April 27, 2011, 02:44:32
I personally wouldn't bother with the battery disconnect. IMHO it will do nothing except be an inconvenience.

Pump the tyres up to 36-38 psi and drive economically. By this I don't just mean accelerate gently but also brake gently and in particular bear in mind that each time you press the brake you are using petrol (not usually high in most drivers' minds). With this thought, develop a driving style that anticipates the need to slow down well ahead and for preference without using the brake. This will help a lot. Economy is to a very great extent dependant on the driver and driving conditions.

You can expect to see continuous improvement as the engine loosens as well (I'm getting my best economy now at 30,000Km+). Even so, with your amount of city driving and being an auto you must expect to use more fuel; the convenience of an auto comes at a significant cost.
Title: Re: Very poor fuel economy
Post by: ryaz11 on April 27, 2011, 09:59:32
thanks so much for all your replys guys. I pumped the tyres to 36psi today so i might put them to 38 just to be sure..

i put fuel in the car last wednesday and now im on half. which i have done 360kms. And thats pretty much town to town driving (10mins to the shops and back)

Hopefully the little i30 is not as thirsty in the future  :rolleyes: lol
Title: Re: Very poor fuel economy
Post by: AlanHo on April 27, 2011, 10:04:56
thanks so much for all your replys guys. I pumped the tyres to 36psi today so i might put them to 38 just to be sure..

i put fuel in the car last wednesday and now im on half. which i have done 360kms. And thats pretty much town to town driving (10mins to the shops and back)

Hopefully the little i30 is not as thirsty in the future  :rolleyes: lol

I hope you used an accurate pressure gauge - our local service station's pressure gauge is currently reading 7 psi too high. I have told the assistant that he should advise his boss that if it isn't fixed within a week - I shall report it to trading standards.
Title: Re: Very poor fuel economy
Post by: eye30 on April 27, 2011, 11:11:06
Observation:

Tyre manufacturers give psi's, when cold, to use based on weight carried.

My understanding is if the car is involved in an accident and the psi varies significantly from the manufactures psi for the weight carried then even if the accident isn't your fault you can be liable.

Any views?
Title: Re: Very poor fuel economy
Post by: Alasama on April 27, 2011, 14:33:44
Manufacturer's suggestion 32psi is indeed too low. That's why most that kind of tires did not wear perfectly. These tires were usually changed to new ones before the end of life circle. It's better to pump higher than "standard". My tires were out at only 14000km. Now I pump new ones to 38psi, it also help the fuel economy.
also,
-Choose low rolling-resistance tires.
-Do not fill up fuel in daytime, especially at noon. The better early morning or evening/night, due to the effect of cold & hot.
-Predict traffic condition in front of you. Slide to slow down when you saw a red light, and try to approach it when it turns green, so that you don't have to stop.
-Remove stuffs on vehicle, which are not necessary to carrier everyday.
-Use cruise control when on freeway.
Title: Re: Very poor fuel economy
Post by: unfamilia on June 23, 2011, 14:12:59
Having had worked in car insurance in a previous job, I have never heard of anyone having a claim refused for over filling tyre pressures. Gauges are not scientifically calibrated as accurate like petrol pumps need to be. 36 to 38 is fine. Drop it to 34 in wet or carrying heavy loads
Title: Re: Very poor fuel economy
Post by: rustynutz on June 23, 2011, 14:34:53
Having had worked in car insurance in a previous job, I have never heard of anyone having a claim refused for over filling tyre pressures. Gauges are not scientifically calibrated as accurate like petrol pumps need to be. 36 to 38 is fine. Drop it to 34 in wet or carrying heavy loads

Carrying a heavy load would be a reason to up the tyre pressure, not reduce it.... :cool:

Welcome, by the way.... :goodjob:
Title: Re: Very poor fuel economy
Post by: Shambles on June 23, 2011, 16:19:30
...Drop it to 34 in wet or carrying heavy loads

Drop the pressure when carrying heavy loads ? :eek:
Title: Re: Very poor fuel economy
Post by: ithurtydeesl on June 24, 2011, 09:32:02
I'd run the higher pressure in the wet as well as it keeps the tread channels open allowing the water to escape, lower pressure will close them up a bit. We used to run  a higher pressure in our wets when racing bikes than we did in our slicks.....
Title: Re: Very poor fuel economy
Post by: unfamilia on June 28, 2011, 13:15:12
We are talking road cars here and stil above 32psi

I've seen some one pop a tyre from too high a load on low profile high pressure tyre. Was once but always made me wAry, Also seen tyre come off the rim from too low pressure but was stretched on the rim.

I've found cars skitish in the wet on too high a pressure, stoping it couple psi brought the road holding back on normal roads in normal driving. I do tend to run slightly higher pressure in the rear tyres when not carrying a load compared to the fronts, 38 to 40 and drop it to 36 when loaded, seems to cushion the ride in my experience.

In my other car 40 to 38 psi all the time but your talking bout a highly modified datsun
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