Petrol Consumption + Wierd High Revs.

[talev788]

I'm getting an average of about 400 k's out of a full tank for my Gen 3 my02

is that normal for my kind of car?

im only filling up with normal unleaded and on average its about 55 to 60 bucks per full tank

am i doing something wrong?

[THERB3]

Its been about 6 months since I have sold our GEN III RX Wagon. I could say I was only getting about 420km including some freeway driving at best.
From my knowledge didn't they have a smaller fuel tank to the GEN IV.

[smythie]

According to redbook, it's supposed to be 64litres.

$55-60 for fuel really only amounts to 45 litres or so. Sounds like you aren't using all the fuel in the tank

[talev788]

According to redbook, it's supposed to be 64litres.

$55-60 for fuel really only amounts to 45 litres or so. Sounds like you aren't using all the fuel in the tank

hmmm... well i'm filling it till it clicks to stop sooo i dunno hey

is there any modifications that can be done to reduce consumption?

[smythie]

Not questioning whether you are filling it properly - I'm suggesting that you aren't running the tank completely empty. I'd guess you have at least 10 litres, probably more left in the tank if it's only taking $60 to fill it from where you think it is empty. I know mine has a good 50km's or so of city driving after the "km's to empty" indicator goes to zero and drops out. The fuel gauge isn't any better - I have something like 10 litres left in the tank when the needle hits the bottom (ie, it takes less than 55 litres to fill a 64 litre tank).

As for mods to reduce fuel consumption, aside from an engine retune, about the only thing you can do to reduce fuel consumption is change your driving style - use less throttle everywhere, coast up to a set of red lights rather than fly up to them and brake hard, use A/C less. If your driving style is already pretty economical, there's probably not so much you can do.

To get an idea of the economy your car is running, reset your trip meter when you next fill it then the next time you fill it after that, take note of the amount it takes to fill the car and the kilometres you have driven in that time. To get your economy in in l/100km:

economy = 100 x litres used / kilometres driven

Until you have an accurate idea of your fuel economy in those terms (or similar - mpg, km/l) you can't be really sure of how economical (or not) your car is running

[Drew]

just a followup - spoke to Vin @ STi ages ago about retuning the 2.5i NA, and he said he has done a few, and the biggest gains are torque, which in theory converts to better economy, as you're not having to pedal as hard to get to your desired speed...

I'm yet to get it done, as the STi dyno is still not in use...

[teK--]

just a followup - spoke to Vin @ STi ages ago about retuning the 2.5i NA, and he said he has done a few, and the biggest gains are torque, which in theory converts to better economy, as you're not having to pedal as hard to get to your desired speed...

I'm yet to get it done, as the STi dyno is still not in use...

That sounds interesting. I am curious as to what exact gains are realistic to expect in terms of torque spread. Also if the tune is potentially $300+ then I would only be doing this for the enjoyability factor. That approach to saving fuel would take YEARS to reap the savings lol.

FWIW driving to/from work in relatively free flowing suburban traffic with top speed zone of 60kph I get 10.5L/100Kms consistently. That's driving fairly conservatively, upshifting at 2700rpm etc. BP Ultimate is used all the time.

[drndrn]

I get about 8.5L/100, but I drive to geelong and back a coupletimes a weeks, although I always hit peak hour city traffic on the way there and back.

[sh1ft]

To be able to tune the 2.5i you wouldn't be able to do much more than bump up the fuel and ignition timing which inturn would prob give you
less km per tank as would be running rich. i could be wrong ????
cos if they were (2.5i) good to get basic tune with decent torque/power upgrade out of them wouldn't more people have done it??? or has it just come up?
i would be def interested in seeing figures and having it done if its proven worth while

if anything it would be interesting to see the difference between the early 2.5i 8 valve motor compaired to the current 2.5i 16 valve

[teK--]

I am guessing that the ignition timing would be advanced especially if the owner is committing to using 98octane all the time. This should improve the throttle response and economy. Also I would want the drive by wire map to be changed so that it is more linear and minimises the ECU's intervention on the driver's throttle control.

If I can achieve both of the above then I would think a tune for $350-$400.00 would be worthwhile.

[smythie]

To be able to tune the 2.5i you wouldn't be able to do much more than bump up the fuel and ignition timing which inturn would prob give you
less km per tank as would be running rich. i could be wrong ????

Not necessarily. Factories often deliver their cars running a bit rich for cylinder cooling, production variations and just general improved longevity. There is a small margin there that even a conservative tuner (such as Vin) can use (often by reducing fuel but also by changing timing of fuel injection and ignition) to improve delivery of power and torque and also to sometimes improve economy.

[julzzychan]

ok, mines 2.5NA too.

my average was around 9.4-9.8L / 100km, providing i drove 30Km + thru heavy traffic everyday at around 8-9am. mines using BP eltimate though, so i am not sure if the following would make a difference! but it might worth trying!

heres my little tips (it works for me at least)

1)try keep ur revs around 1-1.5 when trying to find ur friction point and once u got that and the car start moving, let the car roll around 1 second and DUN FLOOR it at all. then shift to 2nd from around 2-3ish revs, never go beyond 4.5 revs!

2)after filling up ur petrol tank, dun floor it straight away coz that might cause the reading to read about 13L / 100Km...no matter how well u drive afterwards, u will never go back down to below 10L

i dunno if all these are useless or u might heard of other people saying already. but this is how i drive and keep below 10L at all times.

Hope it helps my friend!

[Loki666]

Loki i have that too. Best cure.. Warm the car up.. You should always warm ur car up anyways.. So yeahm, thats how i fixed it

Still having the same issue with the high revs.....does it when hot or cold....when first starting off or when stopping and you engage the clutch the engine revs up to about 3k. Have been back to Subaru multiple times and they keep coming up with different excuses and say they have fixed it but they haven't. Their first reason was because of the fuel in Australia being so crappy they had to do a "relearn for the fuel map", next reason was the "anti stall "when you engage the clutch but they said it shouldn't rev that high..... They said they fixed that too but it is still doing it...... Anyone out there with this problem who has actually found out the cause and a solution???? Would love to hear it

[es2464]

I just bought my05 liberty 2.5i
and found out that its fuel consumption is weird.

it shows around 28 L per 100km
and the distance meter only shows 80km when I fill the tank fully.

the distance increases up to 300km when the tank is on the half way,

and it drops very slowly until the tank has 1/3 of petrol in it.

However the fuel consumption stays around 28 L per 100 km.

I haven't really checked how may kms it can go for a full tank, but i think it was around 450 - 500km.

What's wrong with that?

[LibJam]

my mates '05 30RB was a bit like that. we noticed calculation differences in the consumption readings, which gave him a higher l/100km (even allowing for the 3.0).

Loki - I get the high revs when cold too (max about 2k) but tapping the accel drops that immediately (takes it off cold high-idle).. it's sounding like your high-idle setting is too high, and the temp sensor maybe playing up too so the ecu thinks it's still cold. that could account for the higher consumption and high revs.

oh... do you get serious hesitations during acceleration? the above thinking could be supported by this as the engine could be running rich - hello automatic choke.

Will