Improving fuel consumption - 95 Series V6 petrol 3.4

[Gosling1 Junior Member Find all posts View Profile Close Gosling1]

Although there is a similiar thread in the 120 Series forums about improving fuel economy - this thread is specifically for the 90/95 series.

On a recent trip back home from Victoria, I thought that it would be a good opportunity to check the highway consumption of my Prado. Its a stock 1999 model 3.4 V6, with about 270k on the dial. All regular servicing done at home and has been a great rig for over 10 years.

Towing a bike trailer with 1 dirbike, my gear and no passengers - so pretty lightly-loaded really - the old girl was good for 15.5l/100km on the highway.

This is a pretty reasonable figure according to most of the posts on the 120-forum thread about consumption......

Filled up when I hit home, with the intention to do 100km of city driving and then check the consumption.......well FMD it was abysmal.

23 litres to fill to the first click. Has anyone else gotten a figure like this for city driving ???

The driving was typical 60-80kmh stuff, short trips, driving like a nanna for the whole time. But 23 litres ???? Totally unexpected.

* There have been no engine lights on to signify any faults with any engine sensors;
* The MAF sensor gets cleaned regularly with the proper stuff - vehicle does zero dirt miles anyway (at this time);
* Air filter has been regularly cleaned and dried as per instructions - but it has not been replaced for a while.....
* Plugs and leads only replaced 18 months ago. Vehicle starts and runs perfectly.

The local service manager mentioned that they can do a high-pressure clean of the injectors, which should help with fuel economy. A new air-filter will also help. They also mentioned the fuel filter needing to be replaced.

I will keep this thread updated with any improvements in fuel economy, once the rig has been serviced. Really hoping to pull the mileage back down to where it should be - 15l/100km around town and 12l/100km or thereabouts, on a trip. (Normal highway driving for me almost always means a lightly-loaded 6 x 4 and some gear in the back - but not a lot, no roof-racks or anything like that).

If anyone else out there has experienced the same sort of sh!t mileage and has sorted it out, I would like to know how.......there are probably heaps of punters who have the same issue. Its a great rig but 5km to the litre is just a bit ridiculous.....

[tassie tiger Advanced Member Find all posts View Profile Close tassie tiger]

Work your mileage out over the full tank not just topping up. It never seems to be accurate for some reason that only budda knows.

[pwaddo73 Lurker Find all posts View Profile Close pwaddo73]

I have a 2002 single cab hilux with the same motor and 200k on it and Running Maxis Bighorns.
On freeway and open road I can get 450kms until light comes on. Tank is 70 litres.
City driving I only get about 400kms from a tank.
I have an alloy tray and it seems to use the same amout of fuel fully loaded or no load at all,
also seems to be no difference in economy if I drive like nanna or give it some.

[croozza Avid PP Poster! Find all posts View Profile Close croozza]

Never check your fuel consumption in city driving. Reason being is you can do it again the following day and it would be totally different to the day before due to the large variances in traffic congestion, traffic signals, and time of day.
I recently did the Brisbane to Sydney holiday drive, used 112 litres going down to the south of Sydney, and 100 litres to get back home, this was done while fully loaded with about 600kg of gear. When I do city driving to and from work, I get a bit over 400ks out of the sub tank and varies between 50 to 60 litres for that distance due to traffic and signals.

[Gosling1 Junior Member Find all posts View Profile Close Gosling1]

.....Work your mileage out over the full tank not just topping up. It never seems to be accurate for some reason that only budda knows.....

This time I will check it over 200km not 100. Then 300......see how that makes a difference to the mileage reading.

...I have a 2002 single cab hilux with the same motor and 200k on it and Running Maxis Bighorns.
On freeway and open road I can get 450kms until light comes on. Tank is 70 litres.....

15.5 litres/100km ! identical mileage pretty much, but your city driving is heaps better than mine......

....Never check your fuel consumption in city driving. Reason being is you can do it again the following day and it would be totally different to the day before due to the large variances in traffic congestion, traffic signals, and time of day......

thanks - but here, my drive to work is only 10 minutes, the traffic conditions are essentially identical each day - no difference in congestion or traffic lights (there are only 5 sets of lights between home and work) - and I have to get a city driving figure at some point, to get a baseline figure - hopefully from which I can improve the fuel economy ......basically its only a drive through some suburbs and dropping kids off/picking them up etc....the pattern doesn't change much

[glen_ep Addicted PP Member Find all posts View Profile Close glen_ep]

Never check your fuel consumption in city driving. Reason being is you can do it again the following day and it would be totally different to the day before due to the large variances in traffic congestion, traffic signals, and time of day.
I recently did the Brisbane to Sydney holiday drive, used 112 litres going down to the south of Sydney, and 100 litres to get back home, this was done while fully loaded with about 600kg of gear. When I do city driving to and from work, I get a bit over 400ks out of the sub tank and varies between 50 to 60 litres for that distance due to traffic and signals.

100L from Sydney to Brisbane works out to be 10.8L/100km. Why are your fuel efficiency statistics always so ridiculously good and unattainable by anyone else? There must be something unique about your vehicle, your driving style or the way you measure.

[croozza Avid PP Poster! Find all posts View Profile Close croozza]

100L from Sydney to Brisbane works out to be 10.8L/100km. Why are your fuel efficiency statistics always so ridiculously good and unattainable by anyone else? There must be something unique about your vehicle, your driving style or the way you measure.

We were following my sister up from Sydney, they had their 150 series, but drove at around 90kph.
One thing I did notice was that with the cruise control on, the 150 would vary its speed by about 5kph as my 90 would catch up to it and I would have to slow down then flick it back up as they would then slowly pull away. I think it may have something to do with the 150's extra cog.
On our return home, I was still able to drive for a week to and from work, and that uses between 50 to 60 litres with all of the traffic.
I do tend to read the traffic well, and pre plan my overtaking, as I hate being stuck behind people that keep changing their speed (I call them Kangaroo Drivers), because that will chew your fuel quicker.
I think the total distance from Brisbane to Sydney on the Pacific HWY is around 900ks now due to all the bypasses being built, and that will come down more soon when some newer ones open.

[Gosling1 Junior Member Find all posts View Profile Close Gosling1]

.....Work your mileage out over the full tank not just topping up. It never seems to be accurate for some reason that only budda knows........

Could be something in this .........

Today, I hit 200km since the last fill, all city driving. After using 23l for the 1st 100km, it would be reasonable to assume that over 200km, the fuel useage would be 46l or thereabouts ? ......you would think so.

36.61l for 206km driven. That works out to about 17.5l / 100km........this sounds like a more reasonable measure of fuel economy for city driving ? Compared to 15.5 on the highway anyway.

The only change I made from the previous period - was getting the tyre pressure equal at 40psi all round. The previous pressures were a bit howyagoin - fr 35/36 and rr 37/38.5. Apart from that - no change at all in driving habits from the previous period. Same driver throughout.

Put a new air-filter in today, and will re-measure the fuel useage over 200km again to see how consistent it is.......and hopefully see an improvement.

To put things in context - the driving is essentially identical every day, short trips of only 8-10km max each way. 4 sets of traffic lights between home and work. No long periods of traffic jams or anything like that at all. The traffic patterns down here (suburban ACT) don't vary much at all in the suburbs. I am not going anywhere near the CBD where all the real stop/start action is.

One other change - which will not (or shouldn't) make any change to fuel economy - was fitting up some 1" wheel spacers today - just to get a slightly wider track before the 2" suspension upgrade. The first immediate thing I noticed - was that the steering response was slightly less crisp ? i.e. the steering wheel movement to change direction seemed to take just a bit more rotation of the steering wheel..........NFI if this matters or not - but the wheel-arches look a bit fuller with the wheels pushed out 1" all round

Will update this thread again after the next 200km travelled and see how that fuel economy figure looks.......

[glen_ep Addicted PP Member Find all posts View Profile Close glen_ep]

Yes 17.5L/100km is much closer to average IMO. Anything around 16.5 to 17.5 is what people should expect from a lifted/modified 3.4L Prado. Not to say we shouldn't try to get better, but having expectations of 13L/100km is most likely going to result in disappointment and the vehicle being sold.

My average is a little unstable since installing the supercharger, and it's increased a little. Anything from 17 to 19 is average now - it fluctuates easily depending on situation/driving/wind.

Like croozza said, I wouldn't pay too much attention to short fills either - my most recent fill of 20L after only 80-100km calculates a bit high (20-25L/100km). If we were able to get down to the details, you'd find they probably use 80L/100 when accelerating from traffic lights - or in mine, probably 300L/100!!

This weekend I'm heading south - I'd love to try for a 12/13L figure on the highway but with the 130km winds forecast, I have no hope!

[Gosling1 Junior Member Find all posts View Profile Close Gosling1]

thanks Glen good luck with 12-13 on the highway.......that is the figure I am aiming at in the long run as well. It should be entirely doable. Not sure I could ever get down to 10-11 though ?? That is incredible economy for a 3.4 Prado.......

I will keep going with a 200km distance for the fuel economy measurements - at least for the city cycle. It means that any mods will show a result in a week - 10 days or so.......eventually hoping to get down to 15 around town and 12-13 on the highway. I reckon with some good tuning and maintenance - as well as a light foot - it should be possible. Might even look into the possibility of a water-injection system of some type - years ago when I used to strop around in a HQ van with 308 - I remember fitting up a real simple water-injection system that was essentially just a plate that bolted in under the Holley 600 4-barrel. It used manifold vacumm to draw a fine mist through 2 tubes that were fitted into the plate. This had the effect of making the incoming charge considerably denser, which means better combustion.......and better fuel economy in the long run.

Has anyone tried this on a 3.4 V6 before ? Would be an interesting project I reckon.....

[97prado Lurker Find all posts View Profile Close 97prado]

hello all,
i have a 97 prado 3.4l with 453 000 kms and have checked my fuel usage every fill up.i average 900kms per tank about 13l per 100 and when towing 5m boat average about 16l per 100.has been very consistent since i bought it .great car

[Torrie 72 Senior Member Find all posts View Profile Close Torrie 72]

hello all,
i have a 97 prado 3.4l with 453 000 kms and have checked my fuel usage every fill up.i average 900kms per tank about 13l per 100 and when towing 5m boat average about 16l per 100.has been very consistent since i bought it .great car

Wow! That is great fuel economy mate and its excellent to hear the 3.4L is going so well after so many kays! Well done.

+ another 1 for the mighty petrol 90
Cheers, Ben.

[letsgoplaces Advanced Member Find all posts View Profile Close letsgoplaces]

Hey guys,
Next week i'm going from here to Alice (700k's) to grab a camper trailer then travelling the Mereenie Loop through to Chambers Pillar, Rainbow Valley and back to Alice. I'll keep notes on usage This trip should be nice and easy driving

Last time i drove from Alice to here i used about 16lt's/100. 350k's bitumen, 350k's dirt @25psi and a heavy foot. In the NT i take advantage of the 130kp/h limit

Cheers
John

[Gosling1 Junior Member Find all posts View Profile Close Gosling1]

.....hello all,
i have a 97 prado 3.4l with 453 000 kms and have checked my fuel usage every fill up.i average 900kms per tank about 13l per 100 and when towing 5m boat average about 16l per 100.has been very consistent since i bought it .great car.....

Great figures - but at 13l / 100km, and getting 900km from a tank - that would need a tank size of at least 117 litres to achieve ? I thought the stock size tank in these was 90 litres ? at 13l / 100km from a 90 litre tank, your distance should be closer to around 690km ?

Is the fuel tank in the 90 series the same as 95 GXL ? Maybe its a larger single tank with no sub-tank in the earlier models.......

.... its excellent to hear the 3.4L is going so well after so many kays! ......

While down at the dealer the other day talking about the fuel useage on the Prado, old mate Workshop Manager mentioned some figures about service life for these vehicles, and the 100 Series 'Cruisers. Apparently the designed workspan/life of the 90/95 series Prados is 600,000km, and for the 100 Series Landies, its 1 million km.......this is what they are designed to do from the factory floor. I expect that there would be a few punters here with figures in excess of these already

I found a good article last night from the NRMA, written in 2002, regarding these vehicles. There was an intersting paragraph about fuel useage - here is the link .....and here is the para about fuel economy obtained.....

" ....Fuel consumption of heavy 4WD vehicles is rarely a strong point, especially around the city, and this is certainly true of the V6 Prado. On test, a V6 auto GXL used 17.8 litres per 100 km in city running, while a 4 cyl. manual was significantly better at 13.3. Highway economy was similar for both vehicles, at 13.2 and 12.9 respectively......."

[97prado Lurker Find all posts View Profile Close 97prado]

hello gosling 1
my prado 1997 rv has main tank and sub tank I usually get 70l in main and 50 l in sub I have always emptied both tanks to near empty

3.4l motor still doesn't use oil and feels as strong as new

I have a 2008 4l petrol Toyota single cab ute and the motor doesn't feel as stong as the prado
cheers