I'm still getting approx 400-450km to reserve around town and maaaaybe 600km on highway with cruise control on (latter equating to 9.5L/100km)

Changed O2 sensor with one from MitsFix. Got rid of the unburnt fuel smell but if anything actually made fuel economy worse? :eek2:
Cleaned MAF sensor
Cleaned throttle body (as much as I can without removing it) - It admittedly looks pretty dirty inside
Used engine cleaner on 3/6 cylinders
Replaced fuel cap (was a fuel smell prior)

Car seems to be a touch more responsive but fuel economy is still utter crap. Some people claim 600km around town, I can barely get that on the highway.

What else can I be checking? There's zero smell of fuel in the engine bay so I don't think there's a leaky injector
Air filter looks fairly clean

What about aircon? thats the only thing I can think of that might be drastically different. Mine is always on and its always hot here (Cairns). I set it to 20/22c and it can be as high as 33c outside with very high humidity

How is your air filter? A blocked filter makes for lousy economy.

I think 400-450kms around town is OK if you drive the thing and not baby it like your gunna break it.

The Highway kms is the concern I use cruise and got 400kms from half a tank on the way back from Adelaide last year.

600km around town is generally done on the back of a tow truck, you will struggle to get on a normal tank 600km in one of these cars around town, I dont think I have ever managed it. They are heavy remember.

On the highway is this 100% highway? Ie long trip, fill up and keep going ? and what speed, I find with most of my cars that sitting on 100 is fine, step that up to 110 and it does make a difference.

One thing may be to remove the injectors and get them cleaned, often a dribbling injector will cause more fuel usage as the fuel can not atomise properly and burn

Highway usage was to townsville. The occasional stab to overtake the silly buggers who cant drive. Mostly sitting on 104kph by gps

How much is a new air filter?

And if an injector was leaky would i be smelling fuel vapor in the engine bay?

If the injector is leaking externally, you will smell it and probably see it(depending on which one is leaking). What Mal is talking about is one leaking at the nozzle and you won't see that until it is removed. A proper injector clean (not with a bottle of expensive junk) can be really good. Firstly check your air filter - you can do that in 5 minutes. You will soon see if it is clagged up.

If it's auto, 9.5L / 100km sounds great.
If it's manual and FWD, then pure highway sounds like better might be possible, but I would be so happy with that.

I've been resetting both my trip meter and average speed at each fill up. When I'm driving to work I get an average speed between 20 to 25kph. My AWD uses between 15 to 17L / 100km with my driving in that environment. With longer trips in 80 zones with traffic lights, I get average speed around 45kph and fuel usage closer to 13L / 100km, but still driving spiritedly.
I'm due for timing belt, so I wonder if the old one may have some stretch and throw the cam timing out slightly...

Highway usage was to townsville.

Well there's the issue ..... look at any map and you'll see you've been driving uphill. :rofleek:

The occasional stab to overtake the silly buggers who cant drive.


Sounds a lot like you have a bit of an aggressive driving style there. lol

I got 7.7 L/100 km out of my TJ auto 4 speed sedan on a 300 km country drive, but that was driving with fuel economy in mind, eg sitting behind slower traffic patiently and not kicking it to 120 - 130 to overtake someone doing 10 KPH less than my 105 KPH cruising speed. Yes, the Magna is good at overtaking on the open road, but it will affect your fuel economy.

Strangely enough, half of that trip was with air con off, and the second half with it on. Made no difference at all.

Well there's the issue ..... look at any map and you'll see you've been driving uphill. :rofleek:

Driving North does NOT equate to driving uphill!

What else can I be checking?

When was the last time you replaced your spark plugs?
Take your throttle body off and clean it properly. Refit, and get a good can of Upper Cylinder Cleaner (Subaru one is good) and use as per instructions on can
What grade oil are you using? When was it last changed?
Check all your vacuum lines are connected and where they should be.

Everyone's definition of 'around town' differs. 600km in surburban areas would be a stretch for any Magna.

"Still getting garbage fuel economy..."

Seen this comment so many times in the past, it's not funny.

Often this is a concern because someone spend a lot of time in the car, drives aggressively, and finds they go through $50- $100 of fuel a week.

Just checked, 2001 Brisbane fuel price was 76 c/L for unleaded. Roughly half of what it is today - makes a huge difference as to how happy you are with your "fuel economy".

The quoted fuel consumption sounds about right to me. How much you drive in a week and money spent on fuel is entirely up to you.

My KH drinks like an alcoholic fish in the back streets, mostly because I like to give it a squirt from standstill. Heavy car, auto, and a big right boot do not make for economic driving.
On the highway I'll get something around the 7-10 mark, depending on speed, wind and grade.

Try letting someone else drive for a bit and you may be surprised how much (or how little) fuel they use.
My wife gets much better economy than I do, because she accelerates gentler and generally cruises with a lower top speed.

Sounds a lot like you have a bit of an aggressive driving style there. lol

Even so, I can't imagine 'excessive acceleration' to drop overall fuel economy that much over such a long distance at highway speeds. If I did go from 90 to 150kph back to 104 in the space of a few seconds, then it can't make much difference. Even if the fuel consumption was 5x during that time its only ~10 seconds which would equate to 50 seconds of normal driving = approx 1.5km worth of driving at highway speeds. Do that 10 times its only 15km difference in the tank

When was the last time you replaced your spark plugs?
Take your throttle body off and clean it properly. Refit, and get a good can of Upper Cylinder Cleaner (Subaru one is good) and use as per instructions on can
What grade oil are you using? When was it last changed?
Check all your vacuum lines are connected and where they should be.


Plugs were done 7000km ago. No idea on Oil as I havn't had the car long enough to change it
Used upper engine cleaner already. Will pull the throttle body and clean it easier. Simple enough to remove just disconnect everything and undo a few bolts?
Never pulled one before so would be good to see if theres anything to be wary of

Plugs were done 7000km ago. No idea on Oil as I havn't had the car long enough to change it
Used upper engine cleaner already. Will pull the throttle body and clean it easier. Simple enough to remove just disconnect everything and undo a few bolts?
Never pulled one before so would be good to see if theres anything to be wary of

Were all six plugs done, or just the front bank?
Consider replacing your oil if you don't know how long its been in there. That really should have been the first thing you did after you bought it.

Were all six plugs done, or just the front bank?
Consider replacing your oil if you don't know how long its been in there. That really should have been the first thing you did after you bought it.

all six yes

What sort of oil do most people run? semi-synthetic 10w40? (temps here average 25-32c)

My ts v6 gets about 430 - 470 around town, but I dont baby it too much, if I have to plant my foot I do, but I check everything under the hood insanely now because of some previous issues.

Not having a car long enough to change the oil can be your problem, the first thing you normal do when buying a used car or even new car is change all fluids, you dont know how many ks or how long they've been sitting around until you came along with the dosh.

Another wise investment would be your oil filter like everyones been suggesting, this is a common cause of bad fuel economy.

And the way you drive plays a major part in economy but every car has its limits, even if you baby a magna unless you've got something under the hood to save on fuel, about 750 is the max id say you could expect on free way and maybe 550 around town and this is if you absolutely drive like one of those 85 year olds that takes off slow as a snail and always does 20ks under the limit

Not having a car long enough to change the oil can be your problem, the first thing you normal do when buying a used car or even new car is change all fluids, you dont know how many ks or how long they've been sitting around until you came along with the dosh.

Another wise investment would be your oil filter like everyones been suggesting, this is a common cause of bad fuel economy.

I would normally agree but if you saw the car and met the owners you'd realise there's no funny business going on. The condition is just.... stupid, honestly its stupid how clean and spotless it is. The paintwork is absolutely bloody immaculate. I could set the odometer to 5,000km and it'd be believable. No skimping on maintenance with this one. That said i'll do oil and filter soon

What about the catalytic converter? could that be causing issues?

My fuel usage stats are about the same as everyone is suggesting (TJII wagon 4sp tippy auto). My usual 'self test' to make sure all is well is to find a long, straight, level bit of 80kph road with light traffic and minimal wind, do 80kph and check that the instant fuel economy hovers around the 7.5-8.5 mark on average. Can be a bit hard finding such a road though. +1 on cleaning the throttle body, check Madmagna's cannonical TB cleaning post here: http://www.aussiemagna.com/forums/showthread.php?t=31580

Also regarding thorough throttle body cleaning. It looks like a fairly big job to get it off and sourcing gaskets. Since my idle is perfect (beyond the common very slight shudder at idle) is it likely to make any difference? It did look quite filthy when i had a look

Also regarding thorough throttle body cleaning. It looks like a fairly big job to get it off and sourcing gaskets. Since my idle is perfect (beyond the common very slight shudder at idle) is it likely to make any difference? It did look quite filthy when i had a look


Not that hard to get off, just study the various hoses bolts and clips before you start, lay the bolts etc out in a logical order once you take them off, and take it slow & careful the first time.
No need for a new gasket unless you somehow stuff up the existing gasket, it's metal and perfectly reusable.


Forgot to add - be careful when doing up the throttle body bolts, easy as to over-torque them and strip the threads.

Has anybody thought of checking tyre pressures, or that the handbrake is adjusted properly, or that there's no more than two dead bodies in the boot? Thats what I check first... mostly because they're usually free to fix, unless you get help to bury the bodies.

Not sure how "doing 200kmph+" and trying to achieve optimum fuel economy go hand in hand.

The car is in great condition appearance-wise? Thats great, but a cheap hooker can look great but still give you the clap. Check the car over properly before trying to diagnose it.

And USS Enterprise does warp factor 9.8, stiff shit about that as well as this sort of crap about how fast you can illegally go on public roads has no place in this forum at all.

If you are not able to make a useful suggestion (and not not just a copy of a previous response) then dont comment, there is no need to comment for the hell of it

Some 40 posts have been deleted, I have better things to do with my time guys

Has anybody thought of checking tyre pressures, or that the handbrake is adjusted properly, or that there's no more than two dead bodies in the boot? Thats what I check first... mostly because they're usually free to fix, unless you get help to bury the bodies.

I removed all 3 bodies (still had room for another :ninja:) before setting off. Havn't checked handbrake but I know it doesn't noticeably engage till a good 4-5 clicks up. Tyre pressure are all 36 psi (17" alloys)

I removed all 3 bodies (still had room for another :ninja:) before setting off. Havn't checked handbrake but I know it doesn't noticeably engage till a good 4-5 clicks up. Tyre pressure are all 36 psi (17" alloys)

Okay. Sounds fine to me. I'd be doing the throttlebody/ISC/MAF clean, as well as checking the air filter. Another thing I've found with my Magna is dirty/loose battery terminals - give them a clean last (after you clean everything else) as it will kill two birds with one stone; clean terminals as well as resetting the ECU.

I just got a 3.0 V6 5 speed manual TF Advance before Christmas. I drive it reasonably gently, but give it some poke every now and then, it's the most powerful car I've ever owned. Bendigo to Melbourne, and a little bit of urban driving got just under 8.0l/100km. More regularly I do highway driving to work (Bendigo to Castlemaine, 9km urban at end, 34km 100/110 in the middle), with very little other urban driving. I use my other car for that. I was getting about 8.5l/00km.

I've just had it converted to gas. So will take a while to need to fill up the petrol tank as well to work out the average with both fuels. I do notice the difference when you put your foot down when it's on gas compared to petrol, so I'm assuming it will use more gas.

Well there's the issue ..... look at any map and you'll see you've been driving uphill. :rofleek:

Townsville is south of Cairns, so it was a downhill run, LOL

damn thats not that bad , i get 17L/100 round town, 14 mixed and around 10 highway maybe i use to much right foot tho :D