Isuzu D-max Fuel Economy

[torrenova]

I've had my new D-Max for coming up to as couple of months now and I'm getting a little concerned about 2 aspects of its performance. I hope you guys can assist.

The model is the 3.0L 4 cab Highlander 2WD auto

Sometimes, when pulling away it sounds like it (whatever "it" is) is whirring away without any real power being delivered. This "whirring" does not continue for long but is a little worrying as I do not know what it is. Any ideas ?

Now fuel consumption on a run, say from Pattaya to Bangkok, with speeds up to around 120kph will give me over 12km/l but in town, I seem to have problems hitting 8km/l which to me is less than 19mpg !!!! Even 12km/l is only 28mpg. I thought I should be getting way more than this, specifically after the UK 2.5L version did 40mpg on the motorway and returned 52 mpg in this record breaking test http://www.isuzu.co.uk/#/rodeo_range/3/

Can any other owners advise on their expereince or post links to some useful web based data.

Cheers all.

[warwick7735]

Hi

With regard to the noise I suggest taking it to a dealer, but you should be getting a lot more mpg than you state. I was getting just over 12km/ltr in town, and more like 15 on a run, that was in a 3.0 LS.

Basically in town it worked out at 1000bht for 500kms (that was at 25.34/ltr)

Warwick

[ludosiam]

I believe that the consumption stated in their commercials here in Thailand is based on a downhill run at Doi Intanont with everything but the driver seat, motor, wheels and chassis removed. I have a Mitsu Triton 2.5 and figured out roughly the same consumption, about 1.8 B / km on highways and 2 B / km in the city with current fuel prices.

[Sanpatong]

Sometimes, when pulling away it sounds like it (whatever "it" is) is whirring away without any real power being delivered. This "whirring" does not continue for long but is a little worrying as I do not know what it is. Any ideas ?

It's the turbo that you hear. Sounds like a vacuum cleaner for a bit, then it stops when extra power is no longer needed when you're at cruising speed.

As for fuel consumption: That's indeed not very good. Are you spending enough time in 5th gear? (Preferably: All of the time, also in town as much as possible?) Remember to quickly shift up to as high a gear as possible. That means that also intown you're not getting lower than third gear (when cornering) unless of course there's traffic jams or traffic lights.

I drive a 3.0 Isuzu (not the iTeq common rail though) and my consumption in town is as good or better compared to highway driving. (Especially over 90 km/h fuel consumption goes up a lot, but diesels are really frugal when just putting around town in as high a gear as possible)

Edited July 25, 2007 by Sanpatong

[Boksida]

As for fuel consumption: That's indeed not very good. Are you spending enough time in 5th gear? (Preferably: All of the time, also in town as much as possible?) Remember to quickly shift up to as high a gear as possible. That means that also intown you're not getting lower than third gear (when cornering) unless of course there's traffic jams or traffic lights.

He's going to have problems doing that with his automatic transmission.

[Sanpatong]

He's going to have problems doing that with his automatic transmission.

Oh. Well, that serves as a reminder then how bad auto transmission sucks. Especially what's usually fitted to pick-ups in Thailand.

[Crossy]

Now fuel consumption on a run, say from Pattaya to Bangkok, with speeds up to around 120kph will give me over 12km/l but in town, I seem to have problems hitting 8km/l which to me is less than 19mpg !!!! Even 12km/l is only 28mpg. I thought I should be getting way more than this, specifically after the UK 2.5L version did 40mpg on the motorway and returned 52 mpg in this record breaking test http://www.isuzu.co.uk/#/rodeo_range/3/

Don't get your US and Imperial (real) gallons mixed, 1 US gallon = 0.832673844 Imperial gallons. 12km/L is about 28 miles per US gallon, it's more like 33 miles per real gallon (I think US and Statute miles are the same)

I have a 3.0L New Ranger 4x4, manages to average 12km/L on a mixture of in town sitting and hammering up the highway at 120 ish

As an aside, anyone know why US pints and gallons are smaller, seems odd as they are old units that must have been around when the US was colonised. EDIT found the answer here http://en.wikipedia.org/wiki/Comparison_of...stomary_systems Looks like we (Brits) decided to change after letting you lot (Septics) go

Edited July 26, 2007 by Crossy

[torrenova]

I reckon I got about 9km/L today but it was hard work. I really need some advice as taking it to the garage will, I suspect, just meet with blank faces.

[Hssl]

Bare in mind an auto box will zap about 10-20% of your power and kilos per litre but your figures DO seem a bit crappy.

[Monkeypants]

I reckon I got about 9km/L today but it was hard work. I really need some advice as taking it to the garage will, I suspect, just meet with blank faces.

Assuming you have no visible fuel leaks?

I would say that your problem lies with the fuel pump , it could be mis timed, and easy for a dealer to check and calibrate

Are you getting any exxessive black smoke from the exhaust? especially when revved hard?

Engine timing could also be a factor and again can easily be checked

Turbo could be a likely suspect also.

Lastly injectors could need recalibrating, but that would be my outside bet

Edited July 26, 2007 by Monkeypants

[Lickey]

The whirring noise you hear will be the viscous fan coupling, as you pull away watch the rev counter, the noise will decrease as the revs rise and the auto changes gear, and then build again till the revs catch up, if as one poster suggests its turbo noise, then you have a problem, personally its not turbo noise at the age of your vehicle,

Automatic pick-ups are designed to pull a load, with no load they are a little lost, racing through the gears with high fuel useage, try putting a load on your truck, floor the accelerator and feel the difference, auto trans will sense the load and work acordingly, or you could just boot it till you reach the speed you want then soft soap the accelerator, auto trans will sense this and mantain the speed you want and fuel economy, as for city driving, thats another matter with auto trans,

[torrenova]

Thanks for the assistance folks.

I guessed it might be something to do with the turbo / acceleration etc. just didn't notice it on the Vigo I hired before I bought the Isuzu. Doesn't seem to do it when warmed up though.

As for the auto box, well I can handle a manual in town but my wife probably could not (she hasn't even driven it yet but just gave birth 10 days ago). I was prepared for some fuel usage over the normal manual but nothing like this.

Loads ? it won't really be worked that way, well perhaps occasionally but it was just size, cost, flexibility issues that won through in the decision making process.

I like the truck and apart from a lack of bottom end accelleration which I may have to / be able to live with, its just the bloody fuel economy. The fact that it has that ###### computer thing which tells you average or current fuel consumption is so annoying when you have issues like this !

[Lickey]

No disrepsect Torrenova, but why didnt you buy a nice fuel efficient {even auto} family car, no doubt you have BiLaws with pick-ups who could do the ocassinal load for you, Pick-ups are designed to carry up to 3/4 ton, and they dont work well till they do, running about with an auto pick-up empty will drink fuel, sureley you can hear the engine and feel you are getting nowhere,

Again, the choice is yours,

Regards, Lickey.