D40 Fuel Economy

[KraftyPg]

That's good economy for a D40 that if you believe so many others can't and never will get decent economy. Mine's been fairly consistently in the 10's from day 1 so maybe there's hope I can get it down to constant 9's by the time I get to 50K.

 

[domainmal]

i talked to a guy with a D40 auto 2009,and he only gets 450 ks to a tank and doesnt tow anything with it...hes not very happy at all.
he reckons his pootrol 4.2 was better on economy..

I just had the worst ever 412km and used 70ltr. This was half city driving and half country.
I've been reading most of the posts about reseting the ECU but what i want to know is if I have to disconnect the performance chip before doing the reset?
Thanks
Mal

 

[Old.Tony]

I don't think so. The performance chip is modifying a fuel command from the ECU (and usually just increasing it).

Reset away, but remember to take the thing for a gentle drive with no load up to cruising speed (80-90km/h). Try not to rev it past 2,000rpm if you can, 2,500rpm tops.

 

[domainmal]

Thanks Tony

 

[Scubamurph]

Hmm.... tried the procedure for putting the ECU into learning mode but it did not work.
Followed all the steps but engine management light does not flash.

Anyone got any ideas of what to try next?

 

[Old.Tony]

Don't bother fiddling with it Scuba, it's easier than you think.

When you take off the negative battery lead and press the brake light, ALL of the electrical power in the vehicle is drained and the ECU "forgets" its learned fuel map.

By default, the next time the ECU goes online (you turn on your ignition) it jumps straight into "learn" mode for the first drive (until the ignition is turned off again).

So, pop the lead, hit the brake, return the lead to the battery, take it for a gentle drive, turn it off = job complete and no beating your head against a wall trying to make a fandangled compooterised wotsit thingymadooverlacky flash the right number of times.

 

[Maverick1]

Hi, I am unsure what and how every one is getting great full consumption, I at best are sitting at just over 7km/Ltrs I seem to on the high way would be pushing it to get anything to and up to 500km, As fridays/saturdays trip the last stage I drove 460, fuel light came on after 430km. Being a diesel I was unsure and didnt want to bleed the system so I filled up with jerry. In the total 2400km over the 2 days average was 7.05km/ltr. Mine is stock, with 32" Copper ZTR's with canopy nothing on the roof, but we do sit on average speed of 130-140km, some times up to 160km while passing road trains.

 

[Rich64]

I;ve only had my Navara for 2 months and just went on a trip from Adelaide to the central coast NSW I got around 11l/100 going over and between 18 and 20 l/100 on the way back towing a 2.4tonne van, my Navara is an 07 stx auto with canopy, These figures seem reasonable to me, Any thoughts??

 

[KraftyPg]

Well those sort of averages will help fuel economy greatly. (Maverivck)

 

[KraftyPg]

Rich: I wouldn't be overly worried about those sort of figures, they seem to be fairly average for most D40's on this site.

 

[Old.Tony]

Yes Rich, seems fairly reasonable.

We get better economy when we don't rev the engine over 2,000rpm and don't do hills. Any stress on the rig and the fuel consumption just rises up to about 18LPHK, towing our 1.8T van.

 

[Rich64]

Thanks guys, one thing I did notice is that the max tourque dose not appear to be at 2000 RPM as the specs claim, and I also did 1 leg of the towing trip with the o/d turned off, so cruising at higher RPM and the fuel economy was relatively unchanged, well in line with the other results. I have a friend trying to talk me into a CHIP it chip and a DPF delete, I'm just not convinced it's worth it, the vehicle seems to have enough power and it would take forever to se a return on investment in fuel savings alone, I think..?

 

[KraftyPg]

What is the max torque at then?

As to whether a chip and DPF delete is really worth it can only be answered by you, chip manufacturers can make all the claims they want but at the end of the day if your happy with what you have then is there really any need for more when the off set is a hole in your wallet. Under normal driving conditions I think it will take a long time to recoup the costs of a chip if done for fuel savings alone but most people don't do it for that reason.

As for the DPF you'll probably see hundreds of horror stories on those but at the end of the day there is still many of us running DPF's and getting decent economy. Would we get better economy if the DPF was removed, we'll probably never know just like you wont unless you remove yours. Either way for the cost and under normal driving I doubt you'll be seeing monetary gains in the near future.

 

[Scubamurph]

Don't bother fiddling with it Scuba, it's easier than you think.

When you take off the negative battery lead and press the brake light, ALL of the electrical power in the vehicle is drained and the ECU "forgets" its learned fuel map.

By default, the next time the ECU goes online (you turn on your ignition) it jumps straight into "learn" mode for the first drive (until the ignition is turned off again).

So, pop the lead, hit the brake, return the lead to the battery, take it for a gentle drive, turn it off = job complete and no beating your head against a wall trying to make a fandangled compooterised wotsit thingymadooverlacky flash the right number of times.

Cheers Tony. Will give that a go. I better find my radio code first I guess.

Murph

 

[Burmic1]

Can someone tell me what the hell is a scan gauge , will it help me save fuel, where do ya get it n how much should it cost.
Tow a 2.5 t van and got rid of my petrol paj cause could not afford to buy a petrol station to run it
When towing with the d40 im afraid its not much better
Mick

 

[Old.Tony]

The ScanGauge can be bought here in Australia (here is the website).

It plugs into your car and provides you with real-time information about the vehicle, including current fuel consumption rate.

Towing is always going to use more fuel, but I found the best way to reduce fuel consumption was to reduce speed. Once your tacho passes 2,000rpm, your torque curve is starting to plateau - so you're pumping in extra fuel but you're not getting a lot more torque for it. The magic point in the diesels is just where the turbo comes on strong, which is between 1800 and 2000rpm (closer to the top of that range = peak torque).

Cruising at 2,000rpm gets the vehicle to about 95km/h. Hauling a van at that speed requires a fair amount of power to displace the air - and the faster you go, the more power you need. Unfortunately the power curve required climbs faster than the power curve generated by the vehicle's engine for a given fuel rate, so going any faster than that just burns fuel unnecessarily. This isn't unique to the Navara.

We managed 15.6LPHK at Christmas coming along the Luritja Rd to the Lasseter Highway. That's in 40C+ degree heat, so the intercooler wasn't at its most efficient.

Having changed tyre sizes, I'm noticing that the fuel consumption rate has climbed. I've only gone up a little - to 265/70s from 255/70s - but it's throwing out my fuel economy, and I'm using an extra 1-2LPHK now. I'm not happy about that, but these BFG A/Ts are on the vehicle now and having paid $360 each I'm not about to go tossing them.

 

[KraftyPg]

Will a SG help you save fuel? Only if you set it right and drive to conserve rather than drive to a speed. If you're going to try and use something like SG to save fuel you have to watch the LPH readings as if it were a speedo. Can it help, yes, will it help, not always, how ever when set up it right it will give you a lot of information which can assist you in many things as well as fuel economy.

 

[joe2006]

Given the recent discussion, not sure if I am OT

Done 1400ks now & this last tank equates to 10.9LPH. It is only the 3rd time I have put fuel in but the consumption seems to have come down a bit each time from about 11.5LPH.

 

[Burmic1]

Thanks for all the info gents will look into gettin a scangauge
Mick

 

[KraftyPg]

Mick I don't see a model listed so just be aware that SG doesn't fully work on earlier model D22's. I think it was the 08 model they started becoming fully functional on the D22's but someone else might be able to clarify that, D40's I think they got back a few more years than that.