2.5 Fuel Economy

Posts specific to the 2.5 litre NA engine

Re: 2.5 Fuel Economy

Postby Clearlight » Thu Feb 11, 2016 2:41 am

I struggle to get better than 9 litres per hundred around town , often in slow traffic and lots of cold starts its more like
11 litres per 100 . On the highway its happier times , usually in the sevens . One time last winter , I got down to 6.3 per
100 cruising at 1?0 kph with the air off , running on Shell Optimax . Unfortunately that speed seems to coincide with an
efficient rpm band , but at 100 k its actually using more fuel for some reason .
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Re: 2.5 Fuel Economy

Postby Callicil » Mon Nov 27, 2017 2:47 pm

I'm seeing some nice numbers here. Shame I can't get the same out of my 2.5i. First run with it from about 3/4 tank netted me just under 300km. Second run is looking a bit more promising at this stage.
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Re: 2.5 Fuel Economy

Postby robo498 » Tue Nov 28, 2017 7:38 am

2 things, 1 maybe your o2 sensor is on the way out & 2 speak to Matt from kido tuning and get him to tune the car, I have a 2.5 stock non turbo wagon and was getting 400 kms from a tank, it has gone up to 500 kms (city) now and much better still on the highway. :D
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Re: 2.5 Fuel Economy

Postby Callicil » Tue Nov 28, 2017 9:18 am

Yeah not sure where Kido is located, but was thinking it was the MAF sensor, but still working out where exactly where it is. Not on the intake hose, so I'm thinking it's on the box over the carby. The second tank seems to be going a bit better at the moment. About a 1/3 through and it's on about 200km, so I'll see how it goes after I get it serviced on Friday.

I guess these are the joys of buying a second hand car ey?
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Re: 2.5 Fuel Economy

Postby robo498 » Tue Nov 28, 2017 5:21 pm

Use BP ultimate, subaru's love it. Kido is in Sydney, but then Matt goes all around australia and he will book you in and let you know when he is in town. ....Easy! As you have the Preface I am not sure where the MAF is, on mine it is on the hose from the in take air filter. But Matt can see from the computer if it is on the way out for you. Also he can make your brakes better and make the thermo fans come on sooner to help stop or slow down the leaking head gasket the 2.5's have. If you need matt's details let me know. Get the NGK plugs for the car well. Are you in Melbourne?
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Re: 2.5 Fuel Economy

Postby Callicil » Tue Nov 28, 2017 6:16 pm

Nah I'm all the way over in sunny WA. Was thinking of trying some of the injector cleaner also, as I reckon the car was sitting idle for a while before I bought it. Yeah googling where the MAF is on mine seems to be impossible to find ey. I'll see how it goes after a service, and then if it's still utter crap on fuel, I'll see if I can contact Matt and see what he can work out for me.
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Re: 2.5 Fuel Economy

Postby jamescd » Wed Nov 29, 2017 5:05 pm

Callicil, having an 04 2.5i you might have the untunable Hitachi ECU (just like me, yay)
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Re: 2.5 Fuel Economy

Postby Callicil » Fri Dec 01, 2017 11:48 am

Oh great that sounds absolutely wonderful. So far I have managed to go around 250km to half a tank. Slowly improving.

**Update - 08-12-2017**
Well it turns out the plugs and such had never been replaced. Melted plugs, dodgy leads, filthy filters. Problem solved.

**Update - 16-12-2020**
Turns out you may have been spot on the money jamescd, as I do not have a MAF sensor, which to me is leading me to think that it is as another peron has mentioned in another post that I may have the KA variant, which does not have a MAF, and the ECU is not tuneable/modifyable.
Last edited by Callicil on Wed Dec 16, 2020 10:05 am, edited 1 time in total.
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Re: 2.5 Fuel Economy

Postby Snekky » Wed Aug 15, 2018 4:45 pm

Mine says 25-30 Litres per 100 km, idk if somethings wrong with the system :?
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Re: 2.5 Fuel Economy

Postby Jaza » Sun Aug 19, 2018 9:08 pm

My 2008 Liberty wagon surprisingly got 655kms on a full tank to when the fuel light came on which was United U91 where I drove from Frenchs Forest NSW to Coffs Harbour NSW with a bit of city driving around Coffs Harbour. I notice a huge difference when I switch from U91 to P98 as I get more kms and more performance out of it. I'm going to try BP Ultimate for the first time this week and see how it goes.
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Re: 2.5 Fuel Economy

Postby Jaza » Sat Sep 01, 2018 6:26 pm

Fuel light has come on from using BP Ultimate for the first time and I'm amazed at what it's done. I've done 605kms on a full tank and it's the best P98 fuel I've used and it's the furthest I've gone on P98. I've noticed i've got more kms usually averaged around 570kms on other P98 fuels which were from United and Shell but BP Ultimate gave me better performance, faster acceleration and smoother driving. BP Ultimate is the best on Subaru's then Caltex Vortex is second best. So I'm happy about the fuel economy but i'll be back on U91 as PULP is an absolute rip off in Coffs Harbour averaging 175.9
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Re: 2.5 Fuel Economy

Postby Duck! » Fri Feb 01, 2019 11:13 pm

Duck! wrote:
GTR320 wrote:Wow after reading your comments and what your cars are averaging I think there is something wrong with mine. I average 350 kms on a full tank using 91 fuel. I do a bit better on the 95 fuel but this has me worried. Anyone know what it could be?

Grave dig!

I get more than that with a 650-odd kg trailer hanging off the back! On highway I can get around 700km to a tank (60L in the 2G Outback) without the trailer; best effort was Bright to Melbourne, via Beechworth &.... Echuca (yes, I took the long way home), around 710km. With the trailer it drops to around 430, although on one trip with a ripping tailwind I got it out to 460km. I don't do all that much city driving, so not really sure what it'd blow out to with all that stuff, but generally with mixed driving I'll get around 600.

Second bump!

Anyone else noticed that Subaru fuel gauges/lights are really pessimistic? My old 2G MY98 Outback would get about 100km between the needle hitting the "E" line and the light coming on, and then another 80km after the light came on. Depending on the situation, I'd generally get the light around 580-610km.

However with my current 3G/MY99 Outback, with a nominally 4l larger tank (64 vs the older car's 60), I get the light coming on a lot sooner, at a rough guess with about 15l, maybe even a bit more still in it (the book says it comes on with about 9l to go, the old car's book said 8l). While travelling a few weeks ago I was taking some back routes so had an emergency jerry can just in case, so decided to push things a bit.... 120km after the light came on, and still no indication of fuel surge/starvation when I hit the next town to top up . 670-odd on that tank with a lot of mountain driving.
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