This posting is just to save 2.7D owners from unnecessary fretting.
My investigations all over the web show that the 2.7D engine is astonishingly thirsty when cold. The engine is unlikely to be faulty in some way. Don't be surprized then that in winter weather where you're experiencing ambients of minus 20*C, that your brim-brim figure works out at 22mpgUK, less for gallonsUS (multiply fig. by 7, then divide by 8, for US mpg).
I've tried 0W30 full-synth engine oil instead of 5W30 -- makes no obvious difference. I needed to change mine anyway.
The only device so far to help has been the engine sump heater. (See my other postings on this in Gen. Tech. help). And boy do I know about it when I forget to turn it on! About 2Kw/h are needed to lift the engine oil to quite warm on the dipstick.
I've been looking at remaps, either by plug and play units in the CANbus diagnostic socket, or by bespoke remapping of the ECU, but I'm not convinced for two reasons.
1) They are expensive, £300 being typical.
2) They all seem to increase common-rail fuel pressure (which is high enough already, some at 3000bar) so I can't see that squirting more fuel into the engine will result in better economy. However, I CAN see an increase in power and torque, if that were what I'm chasing.

I HAVE learned that the best way to deal with this engine when cold is drive it at around 45 to 50mph straight away after allowing a 30second idle to get the oil circulating. Of course, if you're straight into city driving and traffic lights like me, you're stuffed.
These engines don't give 'super' economy when driven like a slug -- it's better to keep up with the traffic.
Coasting when hot has shown that a fuel economy CAN be made, as does staying in neutral at traffic lights. Do not ever switch off the engine as an economy when moving, only do this when held up for periods, e.g. slow traffic lights. If you switch off when moving, the autobox will have no pump and become damaged. Also no powered brakes or steering. Dangerous stuff, and the car will keep squawking at you!
Leedsman.

 

Hi Leedsman

I agree completely with your observations on low temperature mpg.

With my own car, if I do a 3.5mile trip from cold (0deg) and then leave car for 2 hours and return, my average is 23 mpg.

If I do a 35 mile trip starting from 0deg the mpg will be 37/38 but if I do the same 35 mile trip with a fully warm engine, the mpg is 42/43.

Your sump heater idea obviously gives benefits and I am pursuing a different approach to achieve the same result. When (if) we get some warmer weather, I am going to remove the front bumper to give access to the Webasto supplementary heater and then I am going to attempt to wire in a switch/timer unit so that it can be switched in at any time - before starting the engine when it is really cold.

There is some doubt if this can be done on the Jag but it has been sorted by Disco3 owners and it shares the 2.7 power unit and so far as I can tell the same model Webasto heater.

It will be too late for this winter but I hope to have it working this way in time for next year.

 

You'll have to keep us informed with the progress of your pre-heater timer: Incidentally, I assume it uses full-taxed diesel. Did you ever do any research into using untaxed red diesel purely for the heater? I understand the customs and excercise allow red to be carried on board so long as it's not powering the engine that drives the vehicle -- ok for an engine powering a 'fridge unit, cabin heater etc.
Leedsman.

 

The burner uses diesel from the cars fuel tank so yes it is full tax. I think it would be too problematic to mount another tank for the heater and to fuel it separately.

I would expect that after using the heater, the mpg figure would improve sufficiently to pay for that burnt during the pre heat and the added bonus would be less engine wear and instant heat in the cabin when driving away.

The webast heater in my car has not worked since I bought it last September and talking to the previous owner, he wasn't aware that all S type diesels have such a device built in so it is quite likely that it has not operated correctly for a long time.

Mine has been checked out on IDS and according to that is ok - but as I have said it does not work. I have downloaded the Webasto diagnostic software and when I get access to the unit will use that to check it out myself and to give the unit a prolonged burn to clear out any crud that may be lurking within. If this is successful then I will fit the timer/switch device to give me control at any time I feel it will be of benefit, not just if it is colder than 5 deg C as Jaguar decided.

The only thing stopping progress is that the Jag is my only transport at the moment and it has to stand outside. From April, I have access to another car and hopefully the weather will be warmer and encourage me to work on the Jag to get at the unit and start playing around with it. Too late unfortunately for this winter but hopefully will be of benefit next year and thereafter.

 

here i the states, most light duty diesels use a cylinder block heater, standard 120V elec plug is easy access under hood(bonnet). heater unit goesinto a core plug hole, and heats engine coolant.

most times you park vehicle close to an 120 outlet, like driveway,or a building.

i have tested temps with a noncontact laser temp gun, on say 15- 20F, temp of engine set overnight would be 85-90F,starts are instantanious, and no smoke or rough idle. and in cabin heater is warm right off!

seems a good trade for small elec power use, rated at 150W.

 

Funny you should mention 120volt, I'm currently running my 'maverick' sump heater on 120volt through a transformer; it has the secondary (!) effect of making the installation safer. I find that some heat percolates through the engine area the longer the heater is left on, in this case four hours or 2Kw/h; my little autobox fluid temp. gauge shows quite a temp. rise in the ATF fluid for instance. FYI in UK 2Kw/h costs around 25p.
I have another economy trick up my sleeve I'm keeping quiet about until fully tested from the mpg records. I keep the random variables about fuel economy under control as much as poss., but the weather is one I can't do much about.
Interesting comments from one contributor about the effect DPFs and catalysers have on fuel economy. Unfortunately in UK any changes under there would be spotted by the MOT testers at once. I suppose one could install a straight pipe through the DPF that coudn't be noticed without dismantling. On this score, much investigations are under way by the boffins on the conflicting needs of NOX, soot and unburnt HC emissions versus fuel economy and the use of EGR. I believe the Japanese have come up with a different diesel engine using a low compression ratio of 14:1 but I can't find out much about it. ATM, I'm still not sure why the 2.7D engine should be so unbelievably thirsty at cold running as I've not noticed this effect so startlingly on previous diesels. I'm wondering if the mapping in the ECU is doing something at low temperatures to alter injection timing for some emission reason? Someone on this website knows I'm sure!
Leedsman.

 

Hello fellas ... and greetings from Australia,

I'll be super careful here to share, not lecture ... because (big shock to me), other than any one-off private arrangement, there appears to be only 2 countries outside the home UK and many European markets, that ever saw this V6 TT Diesel variant ... Australia and New Zealand. So, none of the Americas ever saw these diesel variants (still plenty of opinion; mostly negative hearsay), and we only saw them from mid 2006 (MY07) ... so our exposure is limited. The research I did on this variant, with great help from Jaguar Australia and the staff at Castle Bromwich, occupied all of a year leading up to our purchase of our 2007 model last year, and continues to fascinate and educate me.

So with posts by chaps whose opinions I respect about TTD variants ... I prod myself that Yorkie (2004) and Leedsman (2006) may own very different cars with very different engine and management technologies ... so much so that Jaguar didn't export here until a major upgrade in 2006. Major? Yes; beyond body styling ... little is now made of the diesel upgrades ... new injectors; new turbos; re-work of EGR and DPF cycles and more; but importantly, changes to ECM programming to take advantage of the new hardware.

If we concentrate on just one component, the injector, we find that from inception these were designed and manufactured around ceramic disk rather than traditional solenoid technology. This approach was much more closely aligned to piezoelectric inkjet technology, and includes the following benefits ...

• significantly faster snap-on and snap-off and more precise timing;
• significantly finer micro spray jet streams of fuel; finer than a human hair;
• multiple, separately timed pulses of fuel injection could be programmed in each cycle.

The 2006 upgrade advanced the technology further ...

• revised ceramics provide even faster on/off timings ... unconfirmed evidence that fuel rail pressure was raised accordingly;
• micro sprays in each timed injection are now dynamically programmable for pattern and direction into cylinder;
• the number of pulses in each injector now programmable up to 8 separate bursts in each compression cycle.

One area you chaps might like to focus on (irrelevant in OZ) is how much later technology was retro fitted to the early cars (which we never saw), by changes in hardware and ECM re-flash. Some anecdotal reports that this did/didn't happen; more that it was limited to minor changes in ECM programming. No TSBs or advisories are known here.

What we also know now, is that all this 2006 development came at a cost ... fuel spec was now raised to an unremitting Premium Distillate rating. Suddenly, with this fuel readily available out here, Australia/NZ became a viable Diesel S-Type market. The motoring press here went ballistic ... one of our most respected voted the 2.7L TTD S-type Luxury as "Car of the Decade" ... but cars were too few; too late. Alas by now, VINs were up over N80xxx, and V6 Diesel production struggled through 2008 with numbers dwindling.

I do hope this helps in some way ... even if only to highlight the caution you should bring to comparing your 2 cars. Much more on the UK forum. Notice how diplomatic I have been in avoiding comparison with your fuel consumptions when operating in "arctic" weather? Still a few days of winter remain here ... and 22C (72F) today.
Best wishes,
Ken

 

Hi I just wanted to point out that the Webasto heater is quite a fuel guzzler. Its a 5kw heater and as this stays on if the outside temp is below 4deg I think this is the reason for the high fuel consumption. I have one of these fitted to my narrowboatfor central heating and it does use a lot of fuel.

 

Oh yes, it certainly makes a difference when the temps drop and the Webasto heater kicks in, I notice a big drop in economy, however, for me it's not the end of the world as it's only for a few months of the year.

 

Gas guzzler? It only uses 500ml/hour at full whack and then half of that when halfway up to temperature.which is achieved within 10 minutes from zero de degrees
The fuel that supplies the webasto is not registered thro the on board computer.
I have introduce a switch to select webasto on any time I want up o ambient of 15 Degrees.

 

I always reset one of the trips when I refuel, milage and mpg. That enables me to work out the fuel used between any two points A and B

Fuel used (A to B) = [miles (Reset to B) / mpg (R to B)] - [miles (R to A) / mpg (R to A)]

Then mpg (A to B) is simply Dist (A to B) / Fuel used (A to B).

My best ever mpg was (starting hot, which cheating a bit) was from Gloucester Services on the M5, up the M5 and M6 and into the middle of Stoke-on-Trent ... 48.0 mpg(Imp) [or 40 mpg(US)]

That trip also gave me my best round trip (cold start) mpg ... 46.6 mpg(Imp)

The worst was a journey of 1.5 miles from a cold start ... 14.1 mpg. The second worst was 3 miles from a cold start 22.1 mpg.

As to those figures being particularly thirsty I think a 2.7 litre 6cyl petrol engine that was lugging around 35 cwt of car would be pretty thirsty when cold too.

 

I have a 2006 diesel s type I get aroung 18mpg in town and 42/45mpg on the motorway.wanted to disconnect the pre heater as it looks like engine is on fire when its working. funny looks at traffic lights

 

Take out the fuse, there is one, I don't know the number.

 

I use 'advanced' diesel (eg Shell Nitro-plus) and I've never seen even a whiff.

On the other hand I did once use the SDD to prime the heater, and then do a test run ... the whole car vanished in an enormous cloud of smoke.