Suggestions to improve my poor fuel economy

LIFTED · Post by **LIFTED** » Sun Sep 18, 2011 7:51 pm

Hi Guys
I recently been recording my km travelled and the amount of fuel I put in, in my new 92 2.2l auto liberty.
I'm averaging around town 12.5 litres per 100km:o (that's worse than my auto 3.8l v6)
I've been driving it like a Granny and 12.0 is the best I can get.
Any tips or suggestions or mods on how I can improve the fuel economy and yes I do want to keep it as an auto.
Tyres are running at 36psi, air filter is brand new.

niterida · Post by **niterida** » Sun Sep 18, 2011 8:05 pm

Unfortunately thats about right for your car. Its all I was getting out of my 96 auto Liberty too. You can try resetting the ECU, changing the O2 sensor, checking everything else is working 100% - TPS, knock sensor etc but realistically you won't get much better around town - I would say 11l/100km would be the best you could expect.

Bizarrely though I used to get 10l/100km out of my V2 STi RA powered manual wagon

Even on the highway with my ultra low ratio gearbox (3500rpm at 100kmh) I used to get the same economy !!

LIFTED · Post by **LIFTED** » Mon Sep 19, 2011 8:53 am

Thanks niterida,
That is bizzare I think Subaru's economy is a "mystical art"

steptoe · Post by **steptoe** » Mon Sep 19, 2011 9:13 am

I think it has been the case on most 4 cylinder cars to deliver smilar economy to sixes and eights around town - our deceptive perception they are economical like some motor bikes also not. In some cases they use less fuel but not much less. Highway economy also surprises some. Most of my subes have been consistent in much the same economy highway or town . A mates VS Maloo ute 5.0 gives him 9.9 to the 100 km on the highway so long as he does not sink the boot in ! Laughs at me getting not much better

But then I have two diffs to run away from his laughs - into the dirt !!

steptoe · Post by **steptoe** » Mon Sep 19, 2011 10:05 am

have also read somewhere on a cooling system component web site that the temp an engine is most efficient at is 95C bit too hot for my liking says he who runs about 75C

Post by **TOONGA** » Mon Sep 19, 2011 10:28 am

look at getting the injectors serviced, you will probably find that they are the originals and have never been serviced.

Sorry never had a chance to do it

I'm surprised though as I was getting 10/100 on the highway and 11 around town.

does your foot have extra lead in it?

are you using the economy button on the side of the auto shift lever ?
(should be a green light on the dash) or are you driving around in power mode? (was a yellow light but it doesn't work any more)

TOONGA

mud_king91 · Post by **mud_king91** » Mon Sep 19, 2011 1:03 pm

Thats sad my 3L 6cyl benz gets 14.5 city and thats like a brick compared to a lib

NachaLuva · Post by **NachaLuva** » Mon Sep 19, 2011 6:22 pm

just worked out my '98 Forester's economy...since iv bought the car iv got 10.8L/100km, mixed city/highway. Bought it from my bro-in-law who kept log from new. He was getting from 9.2 - 11.9L/100km. Petrol was 63.5c/L

LIFTED · Post by **LIFTED** » Mon Sep 19, 2011 6:28 pm

No lead in my Granny foot

I tried one test of traveling 102kms around town trying not to let the revs get over 2700, used 12 litres, I even fill up at the same station and pump I've been using the 92 octane(the cheap one)
Yep green economy light is on. Does that injector cleaner stuff in a bottle work/help or is it snake oil?
Just after economy improvement ideas and suggestions.
Steptoe does a cooler thermostat help, why do you choose 75 degrees?

TOONGA wrote:look at getting the injectors serviced, you will probably find that they are the originals and have never been serviced.

Sorry never had a chance to do it

I'm surprised though as I was getting 10/100 on the highway and 11 around town.

does your foot have extra lead in it?

are you using the economy button on the side of the auto shift lever ?
(should be a green light on the dash) or are you driving around in power mode? (was a yellow light but it doesn't work any more)

TOONGA

littlewhiteute · Post by **littlewhiteute** » Mon Sep 19, 2011 7:06 pm

Your problem is you are using crap 92 octane.

And E10 fuel is even worse for bad fuel consumption.

Any EFI car will benefit in the long term from PULP.

I've been telling people for years and the tests were on Today Tonight recently about the fuel economy benefits from using 98 octane PULP.

Yes, the fuel is more expensive, but cents per kilometre generally works out cheaper.

NachaLuva · Post by **NachaLuva** » Mon Sep 19, 2011 7:20 pm

mainbreak wrote: Yep green economy light is on. Does that injector cleaner stuff in a bottle work/help or is it snake oil?
Just after economy improvement ideas and suggestions.

Most of it is totally useless, total waste of money.

Recently i tried Flash Lube injector cleaner...used at recommended dosage (50ml per tank from i think 250ml bottle so good value). Maybe 100kms later i was sitting at a red light n noticed how smoothly the engine was running. It had been bit rough before. Havent noticed any increase in power tho doesnt mean there isnt, just i havent noticed lol. Cant comment on economy as i only just got the car, altho the old figures in the log book suggest its a lot better now.

Basically most injector cleaners "look" good on the shelf, pretty colours n nice labels, but no benefit except to their profits!

Give Flash Lube a go, im a big fan now.

niterida · Post by **niterida** » Mon Sep 19, 2011 7:21 pm

littlewhiteute wrote:Your problem is you are using crap 92 octane.

And E10 fuel is even worse for bad fuel consumption.

Any EFI car will benefit in the long term from PULP.

I've been telling people for years and the tests were on Today Tonight recently about the fuel economy benefits from using 98 octane PULP.

Yes, the fuel is more expensive, but cents per kilometre generally works out cheaper.

That only applies to newer EFI cars that have ECU's that 'learn' and can change the tune to suit the fuel. Something as old as Gen1/Gen2 Liberty probably doesn't apply. Certainly didn't make any difference to my Gen 3 Outback - which by the way I get just over 10l/100km around town but town is Geraldton so its a lot more free flowing than city traffic

2nd Hand Yank · Post by **2nd Hand Yank** » Mon Sep 19, 2011 10:04 pm

Don't take a possum's age to get up to speed mate.

Playing around with several EFI cars with on-board instant and average mileage features,
I noticed that if you take say 10+ seconds to get up to 40 km/h vs. 5 seconds,
you actually start using more fuel because of running time.

There's also a big difference in how much throttle you need to BARELY maintain cruise speed,
and that just a little more that doesn't seem to accelerate the car at all but makes a little more noise
(extra manifold pressure is the noise which uses extra fuel, but no speed increase)
When you get to cruise speed, try driving like there's an egg between your foot and the throttle,
that could break at any moment.

36psi? Eeek.
What's the factory tyre pressure?

The previous owner ran 34-36 psi, but my car is rated for 28-32 psi.
I usually run 32 psi for economy, without getting too much of a jolt over bumps.
I think he might have gained about 5% in fuel economy,
but what an expense in ride harshness.

If you're very keen on high mileage,
see if you can find very skinny tyres that still have enough load rating.
Lightweight wheel and tyre combo would also help.
*and keep your current tyres for when you want to play

My Civic had 195/65R-15's for winter tyres and 205/55R-16's for summer tyres.
When I'd switch to my winter tyres, it drove like it lost 200-350lbs (1-2 adult passengers

)
They wheel and tyre combo netted only a 6 lb drop at each corner
but the narrower tyres were also a tread design for lower rolling resistance.
My winter tyres could only give me 2/3'rds the G-Force of my summers,
but what I lost in g-force, I gained at least half the difference in ease-of-acceleration.
I think I'd also gain about 5-7% in fuel economy between tanks with my winter tyres on.

I second the idea your car could be in need of tuning and/or cleaning.
My L Series for an old car, it sounded nice when I bought it,
but it sounds and runs so much better with new leads and now, 95 octane.

YouTube · Post by **El_Freddo** » Tue Sep 20, 2011 11:04 am

2nd Hand Yank wrote: 36psi? Eeek.
What's the factory tyre pressure?

The previous owner ran 34-36 psi, but my car is rated for 28-32 psi.
I usually run 32 psi for economy, without getting too much of a jolt over bumps.

36 psi will improve your economy without giving a real harsh ride. I've always run 36 - sometimes on longer trips I'll ramp it up to 40 psi. I know Venom runs about 44 psi.

32 psi is about what you would always run for comfort with the best possible economy from what I know. If you're looking for gains in economy you'll need to run a higher pressure, not go 4wd'n, use a light foot and if you've got it use your cruise control when possible - this has drastically improved my fuel economy over long distances!

Mainbreak: If you've not put a can of upper engine cleaner through your EJ I recommend you give it a go. My EJ's running better since putting a can through it, not a lot of smoke but there was still a bit there. ScubyRoo put a can through on one of our 4wd trips and his EJ created a smoke screen!

The auto is always going to suck power and economy from an engine. I had a '78 chrysler lancer that was a 1.4 litre with a slush box behind it. Drove pretty well but economy sucked! I'd be lucky to see 400km from the 45L tank when driving it nicely. I dropped a 5 speed manual in it and instantly got a 100km more from the same amount of fuel without changing my driving habits! I got VERY good economy from it after the manual went in.

Cheers

Bennie

NachaLuva · Post by **NachaLuva** » Tue Sep 20, 2011 4:00 pm

El_Freddo wrote:The auto is always going to suck power and economy from an engine. I had a '78 chrysler lancer that was a 1.4 litre with a slush box behind it. Drove pretty well but economy sucked! I'd be lucky to see 400km from the 45L tank when driving it nicely. I dropped a 5 speed manual in it and instantly got a 100km more from the same amount of fuel without changing my driving habits! I got VERY good economy from it after the manual went in.

Cheers

Bennie

Yeah the old autos were pretty horrible. Bad economy, harsh changes & lots of power lost. I dont know how much power modern electronic autos lose but i dont think its much. As for fuel economy my huge tank of a AU Falcon Wagon with 4spd auto would get 550kms per tank (i think 60L). When its cruising the revs drop way down, saving fuel. Eg, 1200RPM @ 80kmh. Go up a hill & up it goes to 2000RPM. Coast down a steep hill under no throttle & it drops to 750RPM. To get the same in a manual you'd have to be constantly changing gears for maximum fuel efficiency...who's gonna do that!

It always used to be for maximum economy get a manual but times are a-changin'

mud_king91 · Post by **mud_king91** » Tue Sep 20, 2011 8:35 pm

littlewhiteute wrote:Your problem is you are using crap 92 octane.

And E10 fuel is even worse for bad fuel consumption.

Any EFI car will benefit in the long term from PULP.

I've been telling people for years and the tests were on Today Tonight recently about the fuel economy benefits from using 98 octane PULP.

Yes, the fuel is more expensive, but cents per kilometre generally works out cheaper.

+1

taza · Post by **taza** » Tue Sep 20, 2011 9:02 pm

nachaluva what fuel economy do you get out of your 98 manual Forester? I get about 450km to a tank around town in my 2001 but I am very heavy footed. and 52ish L fuel up.

With upper engine cleaner do you just spray it down the air intake? Wouldn't this hydrolock an engine or cause damage?

sven '2' · Post by **sven '2'** » Tue Sep 20, 2011 10:01 pm

taza wrote:
With upper engine cleaner do you just spray it down the air intake? Wouldn't this hydrolock an engine or cause damage?

use the OEM Subaru UEC

And no, your engine will be fine - Subaru specify it at major service intervals

taza · Post by **taza** » Tue Sep 20, 2011 10:38 pm

sven '2' wrote:use the OEM Subaru UEC

And no, your engine will be fine - Subaru specify it at major service intervals

Im guessing you spray it down the throttle body after removing the air filter on a N/A EJ or put it down a vacume hose? Would either way work?

Taza

2nd Hand Yank · Post by **2nd Hand Yank** » Tue Sep 20, 2011 10:57 pm

nachaluva wrote: It always used to be for maximum economy get a manual but times are a-changin'

RPM alone doesn't dictate your rate of fuel consumption.
There are other factors like manifold pressure and engine powerbands
(the flattest part of the torque and horsepower curves)

I could get great economy from my 08 Civic running at 3800rpm @ 135km/h,
often the same, sometimes better than the economy I usually get at 3300rpm @ 110km/h
(^^ approximate stats)
It's pretty funny, because the engine sounded like it was working harder,
but that could have been deceptive because of the different musical-pitch of the engine.