D40 AUTO fuel economy

[Old.Tony]

White smoke is generally a sign of an injector problem (for example, varnish on the injectors making them stick open). It's sometimes cleared up using injector cleaner in the tank or by having the injectors sonic-cleaned. Naturally it could also be caused by wearing (pitting) on the injector, which can be caused by oxidisation or physical damage from dirty or contaminated fuel.

 

[Bosshog]

Hey Bosshog, do you think the white smoke is due to the dpf deleted or something else?
I will be doing some mods in the near future eg dpf delete, exhaust and chip and want to get it right.
cheers

Arty

White smoke is generally a sign of an injector problem (for example, varnish on the injectors making them stick open). It's sometimes cleared up using injector cleaner in the tank or by having the injectors sonic-cleaned. Naturally it could also be caused by wearing (pitting) on the injector, which can be caused by oxidisation or physical damage from dirty or contaminated fuel.

While Tony is correct that a crook injector causes white smoke - that's not the case in this example.

The white smoke is caused by the ECU injecting diesel on the exhaust stroke in order to create a regen (a.k.a. burn) in the DPF. Removing the factory dump pipe/cat changes the gas mixure entering the DPF and this in turns triggers the NOx sensor in the DPF to tell the ECU to do a burn. So without the DPF and no factory dump/cat the unburnt diesel goes straight out the end of the exhaust - most embarrassing!

If you remove the factory Dump/Cat and leave in the DPF your DPF will be working overtime and will not last very long (they are only lasting several years as it is!!). You will not see any white smoke as the DPF deals with it.

If you want to remove your DPF you MUST, I repeat MUST, leave the factory Dump/Cat in place as this will not trigger the ECU into doing a burn. In that way the DPF can be permanently deleted and the ECU will never trip into doing a burn. You'll improve your economy by 1L/100 kms by removing the DPF. Down side is the the factory dump/cat is restrictive and does not allow the turbo to spool up as quickly as an aftermarket one does. Oh and that wonderful exhaust note from a straight through pipe goes too.

Sorry about the length - but there is not too much I don't now know about D40 Series 3 diesel auto exhausts!

BH

 

[Old.Tony]

Gus, have you thought about faking the input from the NOx sensor (and the O2 sensor for that matter)? It's just a voltage. Whack in a potentiometer and see what happens? If you can fool the ECU into the right reading, it might just give you back the economy and remove that white smoke.

 

[Bosshog]

Gus, have you thought about faking the input from the NOx sensor (and the O2 sensor for that matter)? It's just a voltage. Whack in a potentiometer and see what happens? If you can fool the ECU into the right reading, it might just give you back the economy and remove that white smoke.

Thanks Tony - a what meter?

 

[shero82]

just filled up my d40 auto king cab for the first time and put 67L in for 534k's giving me 12.3l/100 - not too bad i thought. that's with a good bit of city driving and a little bit of freeway.
these figures are also with the "full tank" that nissan gave me so there may be a few more k's in there too.
i'm going to block the egr tomorrow so i'll see how the next tank pans out.

shero

 

[stxowner]

Latest fuelup
663 KM for 69 Litres @ 10.4L/100K All city & freeway crawling.
Not the 9.0 listed in the sales brochure but no worse than the SV6 Commodore I drove for the last 3 years.

 

[dpalcat]

630km for 78 Litres All city km's

2009 D40 Titanium T/D Auto

 

[Dave]

Thanks Tony - a what meter?

Potentiometer - Wikipedia, the free encyclopedia

Commonly known as a pot.

Dave.

 

[Old.Tony]

630km for 78 Litres All city km's

2009 D40 Titanium T/D Auto

12.38LPHK isn't bad for around town.

 

[stxowner]

Latest fuelup
663 KM for 69 Litres @ 10.4L/100K All city & freeway crawling.
Not the 9.0 listed in the sales brochure but no worse than the SV6 Commodore I drove for the last 3 years.

Keeps getting better at the moment. Filled up twice yesterday, first time after 440K city driving used 44L at 10L/100K. Then had to drive Perth to Bunbury and back so took the opportunity for a bit of an economy run. Most of the trip was at 100Kph on cruise control with aircon on. Result was 360K used 32L at 8.9K/100K.

 

[KraftyPg]

Looks like while their actual figures are still done under ideal conditions Nissan have made some head roads into improving economy in the newer models. As you say Perth to Bunbury is a good economy run and it looks like you've got very little to complain about in the fuel area of your Nav.

 

[Pete22]

12.38LPHK isn't bad for around town.

This is what fascinates me Tony....I regularly get 11.5 around town but on a highway run I rarely get under 14....go figure....oh and I drive like Miss Daisy

 

[Pete22]

Keeps getting better at the moment. Filled up twice yesterday, first time after 440K city driving used 44L at 10L/100K. Then had to drive Perth to Bunbury and back so took the opportunity for a bit of an economy run. Most of the trip was at 100Kph on cruise control with aircon on. Result was 360K used 32L at 8.9K/100K.

I only get those sorts of numbers in my dreams......but I'm guessing that my ute is a bit heavier than your's but still there should be the sorts of differences we are all showing.

 

[Old.Tony]

This is what fascinates me Tony....I regularly get 11.5 around town but on a highway run I rarely get under 14....go figure....oh and I drive like Miss Daisy

Pete, does your torque converter lock at about 75km/h?

I demonstrated this to a friend who had never heard of it. Here's how I did it.

On a roughly flat road, drive at about 50km/h, gently ease off and on the pedal. The engine RPM rises and falls with the movement of the accelerator but the car doesn't really respond.

Increase speed to 80km/h. Now, gently ease off and on the pedal - the car still doesn't respond to minor movements but the tacho stays dead steady.

If your torque converter isn't locking (faulty TCC solenoid, loose wiring, solenoid valve sticking, faulty torque converter and more) then you're using much more diesel than you need, just keeping the thing going on a highway - the light ATF used to give the car smooth gearbox operation also translates into a poor gearbox-rpm/engine-rpm ratio.

So, Pete - how's your torque converter?

Edit: I noticed the thread about your auto shuddering. That's a torque converter issue. How was that resolved? Did they turn the lock off, to mask the problem, or did they replace the torque converter?

 

[stxowner]

Only early days and I am no expert but here are a couple of things I have noticed during my economy run by comparing results on the inbuilt consumption meter.
1. Economy improves noticeably when the gauge fuel gets below 3/4. Now 1/4 tank of diesel is approx only 20 kg so if the economy is sensitive to this then if you have other extras adding weight then this may be impacting on your economy significantly.
2. Difference between driving at 100kph and 110kph is at least 1L/100K. If you are not in a hurry then slowing down a bit is going to save you some $
Cheers....Phill

 

[KraftyPg]

If you're going on the gauge alone I wouldn't take too much notice of 1/2 tanks and 1/4 tanks. I agree that less fuel equals less weight but in general 20kgs on a ute that is already 2 tonne or more isn't going to make a huge difference. A much bigger difference is made when the gauge isn't accurate.

The top 1/4 of my gauge constantly gives me 250ks, the bottom 1/4 gives me 250ks and the 1/2 in the middle only gives me approximately 300ks. I'm not bitching about the economy and it looks really good when the gauge is sitting on 3/4 and the odo is reading 250+ ks and you can tell unsuspecting people that you're logically going to get 1000ks from 80 litres but in my D40 atleast I know that the middle portion of the tank is only ever going to yield me about 300ks not the 500 that the first 1/4 indicates.

As for speed difference I rarely drive on nice flat roads for long distances so the speed even under George always fluctuates a few k's as does the LPH but you're idea is completely right. Across the Nullabor last year I heard people talking about figures of 14LPH and higher (in a variety of cars) yet every day those same cars would pass me at 110, we'd catch up or over take them at different stops, then they would over take us again but at the end of the day we'd end up in the same accommodation the difference being they got there earlier than me. But over that distance at speeds of 94-97 I got there with a max LPH of 11 and an average of low 10's and they were quoting 14's or higher.

Using the rough guide of 3 LPH difference over the 8000ks (there and back) covered that is a 240 litre saving and with the average cost of diesel being 133.3 thats about $320 in my pocket just for getting to places a little bit later than other people. Now I know these figures aren't 100% accurate, are based on averages and don't take into account all factors of driving however it does prove your point that dropping a few ks saves money.

 

[WoodyD40]

hmm ... based on that Krafty - i'd be saving a tank of desiel between melbourne and brisbane return trip, if i slowed down from the 110 to the 95km/hr for the entire trip.

Krafty, do you notice much difference in eccomony between using cruise control vrs driving with the right foot?

 

[KraftyPg]

Depends on the road, even the hills between you and me effect George's economy, at below 95 he drops gears a few times around Gumbya Park area then again this side of Warragul but while he doesn't drop the gears and pick up the rev's as much at 99 (one has to be very careful on the Princes Hwy east of Melb lately there is more 100 zones than 110) I've never accurately measured just how much difference there is with the higher revs for longer compared to the higher revs for a short period.

In general I'd say yes I can drive better than George because I can see hills and speed up or drop off accordingly but on the flat (especially the Nullabor trip) I found that the difference was minimal but the resting of the foot was a blessing.

 

[Old.Tony]

I find the cruise control a little too eager to maintain speed at any cost.

Personally I'm happy for the vehicle to slow down as it climbs a hill. The cruise control isn't, and will throw everything it has at the engine in order to maintain speed.

Just in that alone I'm saving fuel - because generally I won't use more than half throttle even when towing.

 

[KraftyPg]

There is two trains of thought to that though.

Let the car slow because of the hill and then it will gradually speed up if there is a down hill following or give it a little squirt at the bottom of the hill, maintain speed upwards and then lift the foot at the top and the car cruises down at speed or is still at speed if there is no down hill. Neither option is wrong and you'd be really hard pressed to compare one method to the other in terms of gains or loses but the one thing that is certain is that George can't drive like that because he can't see hills and there isn't enough tolerance built into the system to allow for speed increases or decreases.