D40 Fuel Economy

[Old.Tony]

Diesels love cold dense air.

Sure. But from a "vehicular quirkiness" perspective, his performed better up on the mountain than it did at lower altitudes. Similar performance to what he experienced on the mountain is achieved by others at sea level. I am guessing that these are the minor variations in tuning that make each of our vehicles different, and am trying to explore if there's enough cause to go down the path of messing with the ECU so that he can get his mountain-top economy at sea level as well.

I'm just not sure if there's enough gain to be had to pursue the issue much beyond here.

 

[Jason]

I'd bet on a drop in temperature causing the increase in performance anyday before an increase in altitude doing the same thing, no matter what "vehicular quirkiness" in tuning. Don't get me wrong, I believe that differences in ECU controlling fuel/air mixtures can certainly effect performance, but don't overlook the obvious before delving into remapping ECU's etc.

I'd also doubt that most dealers would be playing with an ECU prior to delivery. These guys are flatout getting the pre-delivery wash correct.

 

[Old.Tony]

Haha no doubt at all. The thing for me is that "Nissan factory trained technicians" most probably equals "someone that Nissan trained to follow a set of instructions". They're armed with a widget to stick into the OBD port and look up values, and a book with a minimum and maximum range allowed for each value. If something is outside that range, they adjust so that it's within the range and consider it "serviced". For me, that doesn't necessarily equate to "tuned".

The problem there is that a slight variation in the engine means that the specific range for that value is not always best - it might be a little higher than the "allowed" range, or a little lower. Once you find that sweet spot - like the ignition timing on my old dub - you get better mileage and better performance.

That's where my reasoning is coming from. No dispute about cold + dense = better (I mean, that's exactly what the turbo + intercooler achieve). But tweaking an engine that never gets better than 11L/100km so that it finally gives 8L/100km is where I'm trying to get to.

Maybe. It might not be worth the exercise ... although 3 litres per hundred km is 30 litres per thousand or 300 litres of diesel saved between services. That's $365.70 based on what I filled up at today (121.9) - the savings aren't looking too bad. It's achieving those that is the harder part.

I've no objection to looking at methods of improving the intercooler's performance, either. Could you use a 40 litre tank of water and a misting system to wet the intercooler? Fluid allows better heat exchange than gas (air), plus you get the entropy change due to evaporation. A small pump, some small garden watering system hose and a micro sprayer would probably give that intercooler a major boost, although that sounds like something Jeff Foxworthy would talk about.

Has *that* been done? I think I need to google some more.

 

[Leprechaun]

Haha no doubt at all. The thing for me is that "Nissan factory trained technicians" most probably equals "someone that Nissan trained to follow a set of instructions". They're armed with a widget to stick into the OBD port and look up values, and a book with a minimum and maximum range allowed for each value. If something is outside that range, they adjust so that it's within the range and consider it "serviced". For me, that doesn't necessarily equate to "tuned".

The problem there is that a slight variation in the engine means that the specific range for that value is not always best - it might be a little higher than the "allowed" range, or a little lower. Once you find that sweet spot - like the ignition timing on my old dub - you get better mileage and better performance.

That's where my reasoning is coming from. No dispute about cold + dense = better (I mean, that's exactly what the turbo + intercooler achieve). But tweaking an engine that never gets better than 11L/100km so that it finally gives 8L/100km is where I'm trying to get to.

Maybe. It might not be worth the exercise ... although 3 litres per hundred km is 30 litres per thousand or 300 litres of diesel saved between services. That's $365.70 based on what I filled up at today (121.9) - the savings aren't looking too bad. It's achieving those that is the harder part.

I've no objection to looking at methods of improving the intercooler's performance, either. Could you use a 40 litre tank of water and a misting system to wet the intercooler? Fluid allows better heat exchange than gas (air), plus you get the entropy change due to evaporation. A small pump, some small garden watering system hose and a micro sprayer would probably give that intercooler a major boost, although that sounds like something Jeff Foxworthy would talk about.

Has *that* been done? I think I need to google some more.

You can buy universal air to water intercooler kiits, just do some googling.

 

[Old.Tony]

Bah. See? Not an original thought in my head. I've owned this intercooler for just over 2 weeks now too, should have thought of it sooner. Might have made a buck!

So, since it's on topic, has anyone done the mist system to their rig? How's it perform?

 

[Deejay]

Haha no doubt at all. The thing for me is that "Nissan factory trained technicians" most probably equals "someone that Nissan trained to follow a set of instructions". They're armed with a widget to stick into the OBD port and look up values, and a book with a minimum and maximum range allowed for each value. If something is outside that range, they adjust so that it's within the range and consider it "serviced". For me, that doesn't necessarily equate to "tuned".

Hi Tony, don't mean to scare you but, I went to TAFE when I was doing my Diesel Engine course with a couple of blokes who worked in the service department of Toyota and I got to know them pretty well.

Apparently in Toyota (and most others manufacturers from what I can glean) all of the servicing is carried out by apprentices. Most mundane work, brakes, oils, etc is all carried out by apprentices on up to 6 hoists. Behind these service hoists are two or three maintenance hoists where a qualified mechanic will work on stuff that is a little more detailed than dropping oils and changing pads.

The average car may see a qualified mechanic once or twice in it's life. Now I don't have a problem with apprentices changing my oil, I just get pissed off paying for full mechanics rates when snorks are doing all the work and probably getting paid 15 dollars an hour.

No wonder they want your service work so bad!

Cheers,

DJ

 

[KraftyPg]

Doesn't matter what industry you're in the apprentice always gets the mundane and crappy jobs, it's nothing new that mechanics let the lacky do the grunt work and only step in where needed.

To me the issues isn't so much whether your paying for the lacky or the expert it's the fact that today's Nisssan expert is tomorrow's Toyota expert all they need is the badge on their uniform to change and in some cases the work location (although my local Nissan dealer is a Toyota dealer too so techs just have to change sides in the workshop).

If we are expected to only trust "trained Nissan experts" then I expect my expert to stay in the job once he's trained and only ever work on Nissan's otherwise he's no different to a garage mechanic who has done model specific training.

And as far as tuning and altering the ECU I don't believe it's too much of a stretch to think that while all these dual dealers exist the same expert who fixed the Toyota with some of the changes his years of experience has taught him doesn't make him think he can do the same changes to a Nav and get results. Lets face it who's ever tracked the changes made to the ECU after it's been in for a dealer service.

 

[Old.Tony]

I'm ordering my Bluetooth OBD adapter soon, and as is my custom with any computer-like device, the very first thing I'm going to do is a backup!

Yes, I've already broken in to my satellite navigation box and backed it up. Did you have to ask?

 

[KraftyPg]

Back Up? what's that? Don't you just plug stuff in and hope for the best.

I'm a really bad advertisement for my industry, I never back up anything yet when a home computer comes is for repair the first thing I ask the client is did they have a back up and if my corporate clients don't have back ups automated atleast every 24 hours they don't get any discounts on service and parts.

I think I better stay away from my ECU with that sort of attitude.

 

[Haydos]

Sound's like your an enthusiastic bloke with a lot of plans old Tony. It might be cheaper if you just move up into the mountans.

 

[ants_oz]

I'm getting high 11's, low 12's. Doesn't change much highway or around town.

My vehicle is a manual trans, but is also running 265 mickey thompson MTZ's, roof rack, and hauling a fair bit of additional weight in the way of bar work, aux fuel tank etc.

I understand that mud tyres on their own will add roughly 1 l/100km to consumption. I also understand that a roof rack (empty basket, not just bars) will add around the same.

Another interesting thought...vehicles fitted with standard sized tyres will tick over a higher number of km's per tank that vehicles fitted with oversize tyres. The 265/75's I have fitted will basically reduce the odometer km's by 5 point something (call it 5) percent. So on a 100km trip on original rubber, on the bigger rubber the odo thinks you are only travelling 95km. There is an instant "reduction" in fuel economy (by 0.5l/100km for every 10l/100km).

What's the point of this ramble? I suppose just trying to highlight that simple differences like vehicle spec/fitout can make big differences to fuel consumption, without taking into account driving habits or routes. (On that subject, my wife and I also have a 2007 Mercedes M Class diesel. It is her daily driver. She drives it much easier than I do, but when I take it to work, I get low 10's. SHe get's high 11's. Basically, that's the difference our different commuting routes make to the consumption of that vehicle.)

So while knowing what consumption other people get can sure be useful, what is probably equally useful is understanding what may impact that consumption.

Food for thought anyway.

 

[KraftyPg]

So while knowing what consumption other people get can sure be useful, what is probably equally useful is understanding what may impact that consumption.

That's exactly right, until we get every nav on the same bit of road with the same driver and exactly the same parts fuel figures are always going to be different. Even under the same conditions there are things that can still make the figures different.

With so many mods that can be made having an effect on fuel consumptions it's no wonder there is such a wide range of figures. At the end of the day fuel economy is just one of those things you either accept as is or make changes to improve. But you also have to take into account that what works for one person may not work for you and therefore in your vehicle nothing anyone says should be taken as gospel, by all means try it but don't think it's wrong if it doesn't work.

One of the biggest effects on fuel economy in any vehicle is still the driver, so it's a bit unfair to always blame the vehicle.

 

[SOLID D22]

That's exactly right, until we get every nav on the same bit of road with the same driver and exactly the same parts fuel figures are always going to be different. Even under the same conditions there are things that can still make the figures different.

With so many mods that can be made having an effect on fuel consumptions it's no wonder there is such a wide range of figures. At the end of the day fuel economy is just one of those things you either accept as is or make changes to improve. But you also have to take into account that what works for one person may not work for you and therefore in your vehicle nothing anyone says should be taken as gospel, by all means try it but don't think it's wrong if it doesn't work.

One of the biggest effects on fuel economy in any vehicle is still the driver, so it's a bit unfair to always blame the vehicle.

In saying that krafty we should do a comparison, compare d40 to d22 each model which is raised or muddies, chip or exhaust or both or diesel gas, bullbars etc etc you get my drift basically match up comparing cars and go for a round trip together to get an end result.

 

[Old.Tony]

Driving styles will still differ and provide different results.

I really think there is still value to be had from these discussions. If we expect someone to come along and say "if you use your left indicator while scratching your right ear lobe and wagging your toes out the passenger window at 120km/h you'll get 5.5 litres per 100km" I think there's a lot of us who are going to be disappointed.

But if you say that you did this (eg cleaned your intercooler of bugs) and someone else says they pulled out their air cleaner and tapped it clean, removing 6kg of dirt, each of these little points add up as reminders to us all that there are little bits here and there that we can do to improve our vehicle's efficiency.

The same goes for driving the vehicle. I don't go flat out up a hill, I'll happily let the speed bleed off a little so that by the time I get to the top, I might be 20km/h under the speed limit, but I've not used half a tank to get up there. I prefer to accelerate down a hill where possible.

There's no wonder pill. Just a lot of useful hints and tips and different things to try that may or may not suit us or our style of driving - but there's definitely something here for a great many of us. Official lab-tested comparisons be damned anyway, they'd be financed by a company and skewed in their favour!

 

[KraftyPg]

I really think there is still value to be had from these discussions. If we expect someone to come along and say "if you use your left indicator while scratching your right ear lobe and wagging your toes out the passenger window at 120km/h you'll get 5.5 litres per 100km" I think there's a lot of us who are going to be disappointed.

Of course you'll be disappointed, you'll never get under 6 per 100 with the window open

The same goes for driving the vehicle. I don't go flat out up a hill, I'll happily let the speed bleed off a little so that by the time I get to the top, I might be 20km/h under the speed limit, but I've not used half a tank to get up there. I prefer to accelerate down a hill where possible.

Where as I prefer to speed up a little bit before the hill and maintain most of the speed going up hill and then take the foot off on the way down and let the car coast down hill only applying the accelerator when the desired speed is reached. Of course this driving does require one to be under the speed limit to begin with but who's way is right. It's impossible to tell even if we were both on the same hill but who knows someone might read this one day and decided they like to try one way or the other, as long as they don't expect to get exactly the same results it's all good.

 

[Old.Tony]

It's for this very reason that two different people trying to gauge fuel economy will always come out with different results. But just through discussions like this, other readers will see a different approach and try it and may find it suits them better.

And that, in my mind, is one of the greatest benefits of being here.

 

[KraftyPg]

And that, in my mind, is one of the greatest benefits of being here.

Well people who aren't as good as me...I mean us could come across this one day when fuel is scarce and they might need to know how to conserve fuel. Just imagine if Mad Max had have come across a forum like this after he got his car back, he could have driven sedately out of the refinery and saved fuel by not speeding up the hills and there would have been no need for him to go back and drive that shitty old Mack with sand in the tanker.

Everyone is a winner in the long run, we are doing a good public service

 

[KraftyPg]

I've just done 4000ks across the Nullabor and am pleasantly suprised with the Nav's economy. I'm traveling with about 670kgs in the vehicle and before we left the vehicle hadn't done 5000ks.

The worst I've got out of the car in the last 5 days was 11.3 and that was over 72 litres traveling at an average of 96ks with a howling nor-wester across the bonnet in high 30's heat between Renmark and Ceduna and the best I got was between Eucla and Norseman on 78 litres (trusted the scagauge wasn't lying on the amount of fuel left on that trip) doing 9.6 with little or no wind and cool temps.

With the hills from Norseman to Perth I also averaged 9.9 until I topped the tank up at Mandaring (or however its spelt) with a bit over 70 litres.

Haven't worked out the full trip figures yet but I'll be doing that one day soon just to see how the whole trip compares to each fill.

 

[RockyOne]

My last trip Emerald down to Bundy in our D40 2.5 t/diesel I filled up at 530kms & took 36ltrs of diesel. Mate at work worked it out at 6.8Ltrs a 100kms. ? Zeroed the trip meter this morning as Spanner,our dog mate & I am doing the same trip this arvo Th 24 Dec 2009 to Bundy so will see if I have got it right.

 

[navarian]

You must have had a doozy of a tail wind,i stuggle to get 11.8.
Or is there another secret?