Nissan ute TD42 excecive fuel use HELP

[anj1980]

Hey guys
Iv got a huge problem that has been going on for to long now specialy with the price of fuel the way it is. My nissan TD42 is useing heaps of fuel and i mean heaps, ive had him for nearly 6 years now so i no him inside out, but ths problem i cant solve, 165000ks on the clock
I used to get 630+ks out of my main 90L tank now I get 400-ks and with a 525 quintrex behind him im lucky to get 300ks, so you can see my prodickement.
:crazy:
Iv checked every bloody thing i can think of, ive had the pump and injectors reconditioned, made no differance.He isant blowing any excess smoke pulls well, but labours a bit with the boat behind.had the compresions checked all good.
The motore runs on when you switch it off and is werse when hot I recon that has got werse over the last 6 months it only used to do now and again now it happens every time.
The question is as well would the 315/75/r16 wrangler muddies gear it up to much, I often feal like it has, bottom end to long in the gear, got a big clutch put in but still have to ride it a bit to get him up and going, would this make it use excecive fuel to this extent? may be I need to change the diff ratios.
PLEASE HELP LV TO HERE YOUR THOUGHTS ON THIS COS IVE RUN OUT CEERS. CHARLIE

[Peter @ Aawen4x4]

That size tyre is basically a 35", and if you are still running std diff ratios there is every chance that the tyre and the lift you put in to let them fit is the pretty much behind you using so much fuel!

How high is your lift? Body lift too? What gear do you carry all the time? How much bar work do you have on the vehicle? Do you have a roof rack on all the time? Do you have a snorkel fitted? What tyre pressures are you running? All of those things will effect your fuel consumption to varying degrees, and minimising the lift, body lift, weight carried all the time, less bar work, no roof rack, a good clean airflow thru your snorkel fitted with a ram head & nothing else, a good air cleaner; all that sort of stuff can help, along with all the normal things that help with fuel usage, like good airflow, tuned injector pump, good injectors etc. Done all that stuff??? Address all those issues and see how it goes!

BUT, The engine running on is NOT a good sign, so I'd suggest that you need to get it looked at by a reputable Diesel Tuner, Cooma Diesel, Berrima Diesel, someone like that.

Good Luck!

[anj1980]

Hi peter thanks for the input
im running a 6 in lift bar and winch on the front got bout 600kg in the back at all times but took all that off to see the diff but there was none.no roof rack full set of IPF x4 on the roof.running a snorcle with high flow air cleaner, 3inch mandral exhast with simler dumppipe out of the turbo,everything A1 clean and all servises from new every 5000. I did put on an extra fuel filter/water seperatore it is fixed on the op side of the engin bay than the existing 1 so has an extra 2meters of hose + the filter capasity, im wondering weather the fuel is getting to hot before it gets to the fuel pump therefore thining it to an extent that the pump cant build presure.douse that sound feesable you recon.cheers

[Peter @ Aawen4x4]

The earlier GQ's had their fuel filters on the passenger side of the car, so I can't really see the distance across to the other side being the issue! BUT, the extra reduction in fuel pressure caused by sucking the fuel thru that extra filter and separator MIGHT be the issue?!

I'd still recommend that you get the vehicle to someone like Cooma Diesel or Berrima Diesel. Where is home for you? While those two are the best, there are other diesel tuners out there who are good at what they do, just not quite SO good (well, not yet, anyhow!) If you know of a good one nearby, then get the vehicle there ASAP! If you don't know of one, then tell us where you are and someone will know of one!

They will be able to do everything to get the best out of your vehicle and its diesel engine! And that includes checking that the fuel flow isn't being restricted by anything, let alone the additional filter and separator!

[anj1980]

Gday peter
Im in darwin and unfortunatley arnt so luck to have any eaven half rep diesel specialists, or they would of been my first port of call for sure.Ganna take the prefillter off today and run it withont it for a while and see how that goes,it was the blokes that rebuilt my pump that told me to put it on there cos I used to have to fill up with diesel in remote areas and the fuel wasant allways so crash hot.
Ok thanks again peter.

[Ragster]

When I put 33's (from 31's and 4.1 diffs) on my GQ, I noticed an immediate difference in the gearing and fuel consumption. Going to 35's would make quite a large difference in my opinion.

[Peter @ Aawen4x4]

Altho I run 35's with the std 4.11 diffs on a wagon, Ragster, I still get way better than 4k's per litre, or 25l per 100km! In fact, I have just recently done a drive (no 4wd) where I got 10kpl or 10l/100km; but I was driving with economy in mind and working at getting the best economy I could! Still, I would expect that with 35's and 4.11 diffs on a Ute, anj1980 shouldn't be getting too much worse than 5.5 or 6 kpl (16-18l/100km!) and probly better!! Towing might bring it down a bit, but one of the things about a properly tuned and set up diesel is that adding the light towing loads we are legally allowed in Aus shouldn't really impact on fuel economy very much, at least with the TD4.2s anyway! The 35's definitely WILL make a difference to economy, as will the lift that is necessary to fit them under, and all the gear that is on or carried by the car, but it shouldn't really be as bad as anj1980 is reporting! What sort of economy do you get with 33's and 4.11's Ragster?

anj198, what are you using to work out your economy? Cos if you are using an uncorrected kilometre figure from the odometer, that will be showing significantly fewer km's than you are actually doing, by at least 10%, probably more like 12-15% And correcting the km's to properly reflect the distance travelled will make a big difference to the fuel economy! AND you'll be working the engine harder to turn the bigger wheels anyhow, so that will add to the issues of greater wind resistance cos of the lift, more turbulent air under the car, wider tyres giving more resistance to turning/rolling effort; it all adds up. And if your engine isn't in top mechanical condition, then it will show up as poor fuel economy due to the engine being worked hard all the time!! (maybe you can drop the car a few inches and stick it on 6" wide 31/32" dia Highway tread cheese cutters running at 80 psi, that'll give you better fuel economy!!!)

Do you have a turbo or a Naturally Aspirated TD42 anj? The Turbo jobbies really shouldn't notice the any of that too much, while the nat aspirated will notice it more, but still it shouldn't be as bad as you've suggested! And while the extra resistance to the additional filter is a potential problem, the gain in confidence about clean fuel is pretty handy! Can you replace the OE filter head with the aftermarket unit and the water separator, but put them in the original position? Then change the filters more often, rather than run both sets! That's what I've done - taken the original filter head, primer pump, etc out entirely; and replaced it in the same position with a better pump, filter, and water separator with a sight glass. That way I've got the better filtration AND a water trap, but I don't have any greater resistance to fuel flow and the fuel pressure is actually marginally better too! And at the first sign of poor fuel quality, I change the filters, and then change them again when I know I've got good fuel once again! But all that filter changing and replacing was helped even more by getting the pump tweaked at Cooma Diesel. Made a big difference to the economy AND to the power output!

There's gotta be someone in Darwin who can do a reasonable job on a fuel pump and diesel tuning. Anyone know who's good up there? It's been a while since I've been in need of diesel servicing up that way, and I can't remember any names or anything apart from the fact that the place I always went to was in a tin shed painted dark grey out the back of the 'light industrial' area near Nightcliff!! Patterson someone?? Heavy machinery fella's, they had a pretty good name in the Trucking/Transport industry, that's where I heard about them, and they helped at the time, did a pretty good and reasonably priced job - not many other 4WD's around then tho!

When it comes down to it, anj, you just gotta set the vehicle up well and get the engine tuned as best it can be; so get the tappets done, check the fuel pressure, the airflow, the timing, make sure the pump is doing the best it can, the fuel is as good as it can be, you don't have blocked filters (fuel or air), and the exhaust should be as free flowing as it can. If it's N/a, extractors and a 2&1/2" system with straight thru muffler; if it's turbo, 3" with a 3" dump pipe and turbo exhaust flange, straight thru all the way, no muffler unless you really, really want one! What else? Stick with the big names in fuel, places where transport guys get their fuel - that way you stand a chance of getting good quality fuel, don't buy the cheap discount crap unless you really want poor fuel economy!! What you save in paying less for it costs you more cos of how far you just can't go on each and every litre!!

Look at all the Diesel places in town, ask around about them, maybe someone here can give you better & more up to date info than my ancient history, then get the pump set up, timed, etc as well as it can be! Attend to the rest, filters etc, and see how you go! Work out where the torque curve is, and work to keep the engine in that band, picking your gears to give you the ground speed you need while the engine is still in that torque band, and don't forget that with a lifted vehicle, knocking 10kph off your top speed will make a big reduction in the drag you experience and therefore it'll give you better fuel economy!

Good Luck!

[MEGATROL]

My mate was running a set of 4 spotties on the roof of his GU ute and rekons when he took them off it made his fuel consumption a heap better. so maby try removing the lights and see how that goes. my GQ was the same used to get 600kms outa a tank then fitted 35s a turbo and a 5'' lift with 2'' cablift and now get 400-450kms to a tank. so i guess its the sacrifice u make when modifying a 4wd.

MEGATROL

[BIGDAVET86]

There should be some sort of diesel specialists around, find out where the truckies go. 99% of diesel mechanics/injection shops will be good, its just that berrima and cooma have a reputation in the 4x4 world. taking it todiesel mechanic/injection shop has gotta be better than not taking it anywhere cos ya scared you might not get a well published diesel guru.

I would be loking at driving style and possibly dragging brakes, when mine were dragging it was using a bit of fuel, but that alone would not be the problem. Check the speedo with a GPS and find out just how far out the odometer will be and you might find a surprise. If its out 15% that will take it down around the 21l/100km mark.

Cheers
Dave

[anj1980]

THANKS GUYS ROTE A HUGE REPLY TWICE AND LOST IT BOTH TIMES,HIT THE RONG BUTTON,SLOW LEARNER SO IM GANNA TAKE A DEEP BREATH HAVE A JD AND THROW THE CIMPUTER AT MY UTE, NA ONLY JOKEING BOUT THE LAST BIT IN GANNA HAVE A DRINK BUT AND WILL START PITTING YOUR IDES INTO PRACTICE,IM SURE i NEED TO CHANGE THE DIFF RATIOS FIRST AND GANNA COST BOUT 3000 AS FARE AS i NOW,OUCH.HAVE A GREAT WEEKEND ILL LET YOU NOW HOW i GO. SEE YA

[anj1980]

Hey guys
well iv just come back from a trip pig shooting took the fuel prefilter off for this trip to see if it made any difference to the fuel economy, it didnt so I'm back to the drawing board. Even considering selling the big rig which is my pride and joy, purley because of the fuel costs, its outta control and only gonna get worse. thinking bout getting a smaller lighter bus like the new Jeep Rubicon, if only they would put the 2.8 d in it like the sports version.

[anj1980]

Gday Megatrol
when you put 35 on your GQ did you end up changing your diff ratios to accommodate them. just trying to find someone the has changed them to see how much diff it made, if any to fuel economy 3500 is allot to pay if its not gonna have much of an affect, but realistically it needs to be done anyway I spose.

[Patrolling Paddy]

Gday Megatrol
when you put 35 on your GQ did you end up changing your diff ratios to accommodate them. just trying to find someone the has changed them to see how much diff it made, if any to fuel economy 3500 is allot to pay if its not gonna have much of an affect, but realistically it needs to be done anyway I spose.


anj1980
I have got the 35" tyres and had the ratio's changed at the same time so I've got no comparison of how significant the difference is.
However
I run a TD42 GQ ute with 14psi boost, water/air intercooler, 35" tyres, 4.66 ratio's, 6" spring, 3" body and recently gas too and I am regularly returning 15-16L/100, that's about 600km to a 95L tank.
I think the ratio's will make a big difference especially when towing.

PP

[Ragster]

Altho I run 35's with the std 4.11 diffs on a wagon, Ragster, I still get way better than 4k's per litre, or 25l per 100km! In fact, I have just recently done a drive (no 4wd) where I got 10kpl or 10l/100km; but I was driving with economy in mind and working at getting the best economy I could! Still, I would expect that with 35's and 4.11 diffs on a Ute, anj1980 shouldn't be getting too much worse than 5.5 or 6 kpl (16-18l/100km!) and probly better!! Towing might bring it down a bit, but one of the things about a properly tuned and set up diesel is that adding the light towing loads we are legally allowed in Aus shouldn't really impact on fuel economy very much, at least with the TD4.2s anyway! The 35's definitely WILL make a difference to economy, as will the lift that is necessary to fit them under, and all the gear that is on or carried by the car, but it shouldn't really be as bad as anj1980 is reporting! What sort of economy do you get with 33's and 4.11's Ragster?


Peter,
I haven't checked precisely, but I am estimating around 14L/100km with 33's on. With my 31 A/T's I get around 11/100. I'd agree with you and say it's not just tyre size, but a combination of several things causing the problem.
Cheers

[Patrolling Paddy]

Peter,
I haven't checked precisely, but I am estimating around 14L/100km with 33's on. With my 31 A/T's I get around 11/100. I'd agree with you and say it's not just tyre size, but a combination of several things causing the problem.
Cheers


Ragster

Have you altered the ratio's or the speedo calibration since changing tyres? If not then you could be getting false km readings and your economy may be better/worse than it appears.

This goes for anj too.

PP

[Ragster]

Ragster

Have you altered the ratio's or the speedo calibration since changing tyres? If not then you could be getting false km readings and your economy may be better/worse than it appears.

This goes for anj too.

PP

The speedo reads approx 10km/h fast when using the 31"s and is just about spot on when I've got the 33's on. Although I only found this out by driving through one of those "speed advisory cameras" you see around roadworks sometimes. My economy calculations are only approximate to say the least, but there is a noticeable difference between the 2 tyre sizes.
Cheers!