additional unit of common rail grand Vojager 2.8 crd 2005
 

I bought a unit "The Italian box" specification for my Vojager 2.8 crd 2005.
you think I've done well? I hope to have a saving in fuel consumption ....

Most of these boxes don't work! The cheap ones just fool the ECU into thinking its cold! And pumps more fuel into the engine. I had 3 Tunit boxes running on 3 different cars at one point! Not a bad bix @£485 a go! But not a patch on the high end stuff like stenbauer piggyback boxes...

Well, that surprised me, Tunit boxes are the best box's in the world .. .. [sentence modifier] .. .. probably ! :D

I reckon adding some device to your diesel engine to make it more economical is likely to have the opposite effect. I hate to say this, but the the strong likelihood is that the maker will have already done that to the "nth" degree while still keeping inside the emission regulations. The motivation on the maker to be able to quote the best mpg. possible will be strong.

However, if you talk power output, an increase in horses is quite on the cards, as example, Renault offer their 1.5 dci engine with three different power outputs. The higest power, just over 100horse is noticeably worse on fuel than the other two lower power versions. This higher power is usually achieved by increasing both the fuel delivery and boost pressure. Of course, the stress on the cyl. head goes up, and the possibility of damage goes up too.

My investigations show clearly there is nothing an amateur can do to improve a vehicle's fuel consumption from a mechanical aspect, other than heat up the engine first before you start driving, given the vehicle is well maintained. This especially applies to cold diesel engines which are astonishingly heavy on fuel.

The other requirements for the best fuel consumption are:--
1) Keep the vehicle in good mechanical condition, no brake drag, tyres blown up properly etc.
2) Drive appropriately, like a hypermiler, for best fuel consumption.

Leedsman.

A proper remap can improve fuel consumption. The original map is a compromise between power, emissions, consumption and a dozen other things. If you wish to sacrifice one or more of the other factors you can improve consumption.

don't know much about tuning box's but as far as I can see all they can do is increase fuel pressure and/or extend/delay injection times.

But driving style will make the biggest difference at no cost!

Regards
Richard

A £350 spend on a 2.8 will get get you a non-DYNO ECU remap which should come in at about £10 per BHP and should give about 35BHP+ and 55NM+ of torque, while you are in there get them to switch the EGR off. Economy tuning is a different thing altogether you will be very lucky to get close to 10% more MPG, and, as Richie says that can be easily won [or lost] by the weight of your right clog anyway.

Best of luck !

Re. diesel fuel consumption, as previously posted I have been checking if running the engine in normal driving without the IOD fuse in circuit makes any difference to fuel consumption, and it's beginning to look as if it does, but it's not properly proven yet. As readers will know, I like to have real evidence with proper testing if any of my mods. actually work. After all, an economy mod. for example is no good at all if you have to pay for it!
Example, removing the IOD fuse -- cost, nothing.
Example, remapping the engine -- cost £400?
One can buy an awful lot of diesel for £400. (66.7 gallonsUK approx.)
Also I would like to see hard science-based evidence to show that altering the way the micro. controls the diesel engine by remapping really does work in terms of fuel consumption. And if it does, is it because emission controls are abandoned?

Keeping up the temperature of any diesel engine comes under maintenance, and Vmaxxter will find his 2.5 diesel GV. is more economical now after fitting my second thermostat mod. He says the saving on the job as compared to replacing the original 'stat (which is jammed open) is E200 to E300 as well. Diesel engine temperature really does make a huge difference to fuel consumption.

IF my IOD fuse mod. DOES result in a fuel saving, I want to know why.

Leedsman.

HiYa Leedsman,

I'm following your other post on this subject of IOD 'draw' and MPG consumption. Logic suggest that there's no connection between the IOD [off] and MPG. However obvious that seems to me I'm prepared to believe there may be some other IOD [off] influence coming into play. If the IOD controls :

Remote key fob
Radio
Heater blower
Folding mirrors
Central locks
Interior lights when the key is in the ignition
The power seat

I still can't see why that would have any significant influence on MPG. The IOD [on] is essentially a series of 'this only real time' check & connect on the above items in terms of connecting [and removing] the above to the computer BUS. Its the same job for example that plugging in a webcam or graphics tablet to a computer PORT then booting up would make that webcam or graphics tablet 'live'.

What you are doing is good, pushing the boundaries and testing possibilities costs nowt and may lead to a new insight into potential benefits. For example when you and I ran big-cats I was always mortified when a so called expert read his 5 inch thick reference binder and set the points [schoolboy level] and not the dwell angle [expert engineer level].

Yes, the dwell angle will affect ignition timing re. petrol engine. And there should be enough time for the coil to produce an effective spark.
Re. the diesel and a change in IOD affecting fuel consumption, I suspect the injection timing may be affected, esp. as I know it is variable with temp. in many programs. In my diesel Jag. f'rinstance, they actually said the inj. timing was retarded for two minutes after start-up to accelerate warmup. What they expected to achieve in two minutes is beyond me. There is a clue with the effect of running without IOD fuse in GV diesel --
The engine starts cold with no foot on pedal. But when hot it needs a prod to make it go which is different with the IOD fuse in place. With the fuse in place it does NOT need a prod when starting... So there is some effect there.

Leedsman.