D40 Fuel Economy

[KraftyPg]

When I bought my D40, I drove straight down to burliegh (put the first 10km on the clock) and hooked up my boat, 2.5 tonne with trailer,,, and towed it home at 120kph down the hwy.. My first impression off the D40's tow capability was woefull,, it couldn't hold 5 gear even when I slowed to 100kph....

When I arrived home I noticed the trailer brakes were locked on.. DERRR, I forgot to release them when I left the boat dealer... I cooked the trailer brakes good and propper....

The D40 tows like a dream now.... eespecialy when I release the trailer brakes

Haha...I have had similar happen after dropping the log jinker down from the truck only a locked brake on the back of a semi usually shows itself to you (and other drivers) well before you can get up to 100Ks, the smoke, the screeching and the weird shudder in the backend is usually a fair sign something is wrong.

 

[kramtsew]

The D40 seems arse about face to me as far as economy goes. They are more economical around the city than they are on the open road. I travel to work about 65km each way and drive at a steady 100kmish and get around 11lt/100k whereas driving around Perth I get around 8.5lt/100k.
Whereas my 6lt Commondoor is woefularound town 19lt/100k and on the same trip to work is around 10.5/100k.
Its all god though

 

[Dion]

Its all god though

He works in mysterious ways.

 

[Dion]

The D40 seems arse about face to me as far as economy goes. They are more economical around the city than they are on the open road. I travel to work about 65km each way and drive at a steady 100kmish and get around 11lt/100k whereas driving around Perth I get around 8.5lt/100k.
Whereas my 6lt Commondoor is woefularound town 19lt/100k and on the same trip to work is around 10.5/100k.

Mine is exactly like that, 4x4ing is more economical than the freeway, but in mine it's coz 110km/h is like driving at 200km/h all the time in any car... the very edge of its ability and just off redline, and it chews unburnt fuel.

Not sure what the problem with yours is...

 

[kramtsew]

He works in mysterious ways.

oops....bit of a typo there........its all good.......lol

 

[kaizenfire]

hey guys me new to chat
i have a d40 2008

 

[kaizenfire]

i have a d40 stx problem, if i give the throttle a bit the pressure relief valve on the
efi pops & then you can only do 20 ks a hour, has this happened to anyone else
i have i bort a dud
daz from Bendigo

 

[Old.Tony]

That's still under warranty. I'd be taking it straight back to Nissan and getting them to check it.

Even duds can be fixed. This might be the simplest of problems - like, it might only need a bottle of injector cleaner tossed in the tank!

 

[Pete22]

i have a d40 stx problem, if i give the throttle a bit the pressure relief valve on the
efi pops & then you can only do 20 ks a hour, has this happened to anyone else
i have i bort a dud
daz from Bendigo

You're not the first to experience this problem. It has, I believe, been discussed on this forum and on Clubfrontier [International] and on the Pathfinder forum as well. Some have taken ages to fix but other were fixed pretty quickly. The quick fixes have resulted in a change out of most of the fuel componentry - rail, injectors, lines, and in one case I read the pump as well.

 

[Scotty]

I have D40 man diesel and i am consistantly getting between 8-8.5, yeah i do alot of highway driving, but start stop in arvo's, light comes on at 810km's, do you think i get better with 3" zorst??

Scotty

 

[Bosshog]

I am driving to Melbourne on Thursday towing a trailer which will gross in at around 900kgs. I am very much looking forward seeing what fuel economy I manage to get (or don't get as the case may be!).

 

[Sean]

Hi Guys

I have an 07' D40 T/D auto and regularly drive from Newcastle to Yamba towing a boat that weighs just under a tonne I constantly return fuel figures of 13-13.5L/100klm driving it reasonably hard, so am reasonably happy with that considering the hilly terrain.

I went from Newcastle to Forster recently without towing the boat and the round trip used 8.37L/100klm, admitedly I was driving for economy, but proves that you can get good economy if you really want it.

Cheers
Sean

 

[base_28]

hey guys

i have a 09 st-x manual dual cab 2.5 17000k on it and have been getting round 700k before fuel light comes on and been puttin around 67 to 70L to fill her back up so running less than 10L/100 which im very happy with considering thats a mixture of city and country driving with a trip up the beach every weekend for some fishing and 4wd fun.

 

[Haydos]

Yeah I get much the same from mine, about 10L/100kms. I was pretty excited the other day when I got fures of about 9L/100kms going over Mt Hotham. It must like the snow.

 

[Old.Tony]

going over Mt Hotham. It must like the snow.

I learned something interesting with my Honda Eu20 generator. In the book, it states that if I am going to spend significant times at more than 300metres above or below the altitude that my generator was tuned at, I should have it re-tuned (and I think they mean the carby jets) at the new altitude.

You'll find that your car likes thinner air, maybe. It might be that a tweakable ECU would be beneficial - I wonder if we can do that sort of thing through the OBD port?

Now there's something to look for. An on-the-fly engine tuning tool to help improve fuel consumption. It's just dawned on me that people who are getting bad economy might just have slightly "off" settings in their ECU for the injection system, too - nothing to do with wear and tear at all.

Does anyone else have any info about this sort of thing?

 

[KraftyPg]

It's a viable explanation.
Given that no two cars are completely identical it wouldn't take much for cars coming from different dealers/mechanics who can alter the ECU to have big differences in economy. With so many things controlled by the ECU there is no doubt quite a number of controls that directly affect economy, thrrow in drivers, tyres, chips etc and the variables become massive.

Not sure how the ECU and motor would handle on the fly changes but with the right software and hardware and if you knew what you were doing stopping on the side of the road and changing some of your ECU settings to suit the terrain wouldn't be that difficult, after all the car doesn't know your on the side of a road or in the authorised garage. Of course the fun and games is knowing what to change.

 

[Old.Tony]

cars coming from different dealers/mechanics

That's an interesting point. How many times have you tuned something "by ear" and had it running perfectly, only to find that you're measurably off-spec?

Like tuning an old Volkswagen's ignition timing. I used to use a timing light but found the notch in the crankcase pulley was a little out, so I painted a dot where it should have been and got much better mileage. Mine was just cantankerous.

Variations in construction - which are very minor these days of course - and variations in mechanic's application (which are nowhere near as accurate as computers are) - are going to make sure that every single car has slightly different requirements.

So, when the Nissan boys pull out their book and it says "Widget A has to be pressurized to between X psi & Y psi, and Widget B has to read between 3.8 and 4.2 volts" ... maybe your engine needs a little under X, or maybe 4.3 volts.

If your engine likes a little less air (= richer mixture), then a very marginal increase in the ECU's injector open duration would achieve the same result. If it performs better at sea level, then maybe you'd reduce that duration - denser air = leaner mixture desired = slightly shorter duration on the injector pulse.

I'm starting to think bad, bad thoughts about doing stuff to my 2-week old car already.

 

[KraftyPg]

Like tuning an old Volkswagen's ignition timing. I used to use a timing light but found the notch in the crankcase pulley was a little out, so I painted a dot where it should have been and got much better mileage .

I used to have a Datsun Sunny I did the same thing with.

I'd find it very hard to believe that every mechanic/dealer in the country tunes each like vehicle to the same specs no matter how automated things are. Nissan no doubt give the authorised guys a set of tolerances and they can operate within those which is why so many of them disagree with running things that alter the ECU.

 

[burgo]

Gents,
Most of what you suggest is already there.
Tuning changes with Temperature, RPM Load and a lot of other things measured and sensed by the ECU including barometric pressure.
A problem arises sometimes when MAPPING all this information something goes wrong.
That,s why it sometimes takes several software changes (computer reprogramming) to get it right.
Also the will and/or imposition to initiate the change is required by the manufacturer.
Rd's

 

[Jason]

You'll find that your car likes thinner air, maybe.

I'd say it's more likely the car liked the colder air. Diesels love cold dense air.