potato head Posted November 7, 2011 Share Posted November 7, 2011 Guys, I'm begining to get a little hacked off with the economy that I get out of the old gal and was hoping that some words of wisdom could point me in the right direction to making it better. 1988 Defender 90 200tdi transplant from a 92 D1 235 85 16 Goodyear Wranglers with approx 5mm of thread on them Tyre pressures @ 40 psi Service approx 1800 miles ago Roof Rack Rubber mats in the rear for sound proofing (about the weight of a medium sized bloke) I'm only averaging 25mpg doing my daily routes on country lanes ~ 40-50 mph and at the weekend I did a 100 mile round trip and only got 24.5 mpg at an average speed of 60mph (motorways) I did try a fuel pump tweak in the summer (just to see the differences in performance v's mpg) but after seeing 26.5 mpg go down to 23.5 mpg I soon returned it to the original settings. I understand that summer fuel v's winter fuel will give different mpg returns (approx 10% based upon last years trials) and also that hot weather v's cold weather will have an impact but I just cannot understand why I am not able to see and mpg figures in the 28-30 mark. I have checked all the fuel lines and cannot see any fuel leaks. Any advise? Quote Link to comment Share on other sites More sharing options...
landroversforever Posted November 7, 2011 Share Posted November 7, 2011 You say its a 1988, so the transferbox is I think still a 1.6 unless you've changed it and at that age the gearbox is also the slightly lower ratio. Is the truck revving very high to keep to 60? I know my truck (1.4 but still with the early gearbox) is screaming its nuts off at 60-65) The roof rack certainly isn't going to help things MPG wise. EDIT: just worked out I averaged 26mpg to wales... 23 litres and 133 miles. Quote Link to comment Share on other sites More sharing options...
potato head Posted November 7, 2011 Author Share Posted November 7, 2011 Sorry, forgot that. The tb is a 1.4 and the gear box is lt77 (both Std for the year). It will 70 before it starts to scream. I know the roof rack is not going to help on the motorway (its also checkerplated) but doing the lower speeds there should not be that much of an effect as it already as streamlined as a brick. Quote Link to comment Share on other sites More sharing options...
nicks90 Posted November 7, 2011 Share Posted November 7, 2011 doesnt sound that bad to be honest. i have a 90 300tdi csw, 235/85 mud tyres and a snorkel. around town and A/B roads i get about 25mpg. Motorways and major A roads at 60mph i get high twenties and that drops to low / mid twenties when i go above 70mph. and yes my speedo is accurate. Thats the first thing i always suspect when people report 30+mpg, that their speedo is over reading. In standard guise with standard rubber, most defender speedos over read by over 10%. Thats the difference between a sensible 28mpg and far fetched 32mpg! Quote Link to comment Share on other sites More sharing options...
C18RCH Posted November 7, 2011 Share Posted November 7, 2011 Have you removed the viscous fan yet?I replaced mine with an electric fan on my TD5 and it went from doing 28mpg to 32. You could tell the engine was a bit more responsive too.</p> Quote Link to comment Share on other sites More sharing options...
reb78 Posted November 7, 2011 Share Posted November 7, 2011 I get 25mpg consistently out of my 110 (tweaked 200tdi, AT tyres, brownchurch roof rack permanently fitted, and GKN overdrive). I get this on lanes, or at 60 or 70 for long periods on the motorway. Yours sounds similar - allbeit in a 90 but i would have thought the 26/27 you were getting before fiddling with the pump was about normal - are you sure you put it back to 'normal'? Also, 40psi all round?? I run 28 at the front and 36 at the back on a normally unladen 110. I'm not sure they'll have any effect on economy but might be worth altering the tyre pressures a bit perhaps? Has it had a good service lately (filters)? Checked the pump timing? Cleaned out the intercooler? Checked the boost? Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted November 7, 2011 Share Posted November 7, 2011 Have you removed the viscous fan yet?I replaced mine with an electric fan on my TD5 and it went from doing 28mpg to 32. You could tell the engine was a bit more responsive too.</p> Your viscous must've been seized solid then as there's no way it should make that much difference. Quote Link to comment Share on other sites More sharing options...
potato head Posted November 7, 2011 Author Share Posted November 7, 2011 Have you removed the viscous fan yet?I replaced mine with an electric fan on my TD5 and it went from doing 28mpg to 32. You could tell the engine was a bit more responsive too.</p> Yes, when the engine went in 2 years ago an electric fan was fitted and the viscous removed. Think its only been on twice I get 25mpg consistently out of my 110 (tweaked 200tdi, AT tyres, brownchurch roof rack permanently fitted, and GKN overdrive). I get this on lanes, or at 60 or 70 for long periods on the motorway. Yours sounds similar - allbeit in a 90 but i would have thought the 26/27 you were getting before fiddling with the pump was about normal - are you sure you put it back to 'normal'?Also, 40psi all round?? I run 28 at the front and 36 at the back on a normally unladen 110. I'm not sure they'll have any effect on economy but might be worth altering the tyre pressures a bit perhaps? Has it had a good service lately (filters)? Checked the pump timing? Cleaned out the intercooler? Checked the boost? Yes I'm pretty sure it went back to norm as I checked the mpg before and it was the same when the tweaking was reverted - 26.5 mpg. The tyre pressure was at 40 as the tyres had been put on different rims by a mate and I asked him to just set them all to that so I could let the air out to the pressures that I normally use - 30 front and 35 rear. I have just put them back to 40 as I noticed a mileage drop after I put them on, checked mpg - 26.5, changed pressures and then ran for a month only getting 25. Thought that maybe pressures were part of the issue but it may have just been at the same time as the winter fuel coming in. Filters are all good but not checked the intercooler. Boost is as norm. Pump timing? How do I check that? Quote Link to comment Share on other sites More sharing options...
tacr2man Posted November 7, 2011 Share Posted November 7, 2011 If you are that worried about getting a couple of extra mpg then unless you are using the roof rack all the time , take it off it will make the biggest single difference ! The higher tyre pressures will aid mpg , if not comfort . Viscous fan would hev made a virtually non measurable difference unless as FF said it was seized! HTSH Quote Link to comment Share on other sites More sharing options...
C18RCH Posted November 7, 2011 Share Posted November 7, 2011 I've got no answer to that. Thats what the figures before and after worked out at. I used to do 25,000 miles a year in it so the figures were worked out from quite a lot of fill ups. Quote Link to comment Share on other sites More sharing options...
Retroanaconda Posted November 7, 2011 Share Posted November 7, 2011 My 90 (200Tdi) averages about 30mpg, best I've had out of it has been 34mpg on a long motorway run (to Wales, I tend to cruise at 55/60mph) and the worst has been 26mpg (a month of 1.5mile journeys in the cold!). And yes my speedo is accurate, reads 100% spot on with two different sat-navs with my 245/75/R16 tyres. Changing to 7.50R16 road tyres soon, so that may make a small difference though I doubt it will be noticeable in terms of MPG. Mine has a fair amount of stuff in it all the time too, a lot of soundproofing and trim and a big box of tools/recovery gear etc. So yes there's probably more to be had out of yours. Lose the roof rack if you're not using it regularly. Make sure it's getting up to temperature properly (ie. thermostat in good nick) and that all the air hoses are in good shape. Wash it too, sounds silly but if it's like some Land Rovers I see about with half a ton of mud adhered to the bodywork/chassis then that won't help matters! Quote Link to comment Share on other sites More sharing options...
Tom1809 Posted November 7, 2011 Share Posted November 7, 2011 you think 25 mpg is bad, im about to drop a 3.9 v8 in mine, ill be happy to get 16-18mpg on a long run Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted November 7, 2011 Share Posted November 7, 2011 I've got no answer to that. Thats what the figures before and after worked out at. I used to do 25,000 miles a year in it so the figures were worked out from quite a lot of fill ups. I suppose if the viscous was seized it may over-cool it, which being TD5 would make the ECU run in warmup mode which may burn more fuel than normal. As an aside, this could also be affecting the original poster, if the engine never warms up properly then it won't be as efficient although I doubt it'd make significant difference on a TDi. Quote Link to comment Share on other sites More sharing options...
Lorrick Posted November 7, 2011 Share Posted November 7, 2011 Hi All, after getting my 2002 TD5 11O panel wagon with roof rack a few months ago I have been clocking the mileage and fuel consumption just out of interest. It has proved very beneficial doing it as it started out at 27.8 mpg and gradually was getting worse found a leak on the engine and found the Fuel Pressure valve was leaking, so put it into the local garage and had it fixed, just waiting for the next couple of fill ups to see what difference it has made. Just an idea, but have you disturbed any of the pipework when you have been working on it ? I would think it must be something minor, or the pump setting isn't back where it started from maybe. Cheers Quote Link to comment Share on other sites More sharing options...
JST Posted November 10, 2011 Share Posted November 10, 2011 my 90 - 88 reg with a disco 200tdi (200k on it) does 28/29mpg - hardtop no rack sat at about 65mph on the motorway (265/75 ATs) if i had a rack i would expect to loose 10% which is 25mpg....................... Quote Link to comment Share on other sites More sharing options...
Tanuki Posted November 10, 2011 Share Posted November 10, 2011 As a reference-point, my 2001 90TD5 averages 24MPG, this being a mix of around 20% urban/slow-50MPH-A-road use and 80% motorway, where I tend to inhabit the outside-lane in BMW-chasing mode. Any Defender - let's face it - has the overall aerodynamics of a medium-sized industrial estate. If you're cruising at 80MPH, expect to pay through the nozzle. --Tanuki. "Radclyffe - fetch the toads, we're going to play Wind in the Willows." Quote Link to comment Share on other sites More sharing options...
C18RCH Posted November 11, 2011 Share Posted November 11, 2011 I do enjoy that pastime. They hate it when you overtake them! Quote Link to comment Share on other sites More sharing options...
discomikey Posted November 11, 2011 Share Posted November 11, 2011 I do enjoy that pastime. They hate it when you overtake them! especially in a 33 year old series 3! Quote Link to comment Share on other sites More sharing options...
Range Rover Blues Posted November 11, 2011 Share Posted November 11, 2011 25mpg isn't that bad. How much do you reasonably expect? Quote Link to comment Share on other sites More sharing options...
potato head Posted November 11, 2011 Author Share Posted November 11, 2011 27 - 29 (winter - summer) would be smashing but I guess thats a little too much to have without stripping the thing bare, changing for a 1:2 box and only doing long runs. Quote Link to comment Share on other sites More sharing options...
Retroanaconda Posted November 11, 2011 Share Posted November 11, 2011 From what I've heard, Disco 200Tdi engines seem to do worse MPG than Defender ones. I'm not sure why this should be, unless it has something to do with that slight extra tune they have? Anyway, 30 MPG should be achievable. Lose the roof rack as above, unless you use it regularly. Quote Link to comment Share on other sites More sharing options...
ejparrott Posted November 11, 2011 Share Posted November 11, 2011 My disco 200 has repeatedly returned me 34.6mpg on runs to Wales and to the Lakes, even spending a day laning there. I'm pretty chuffed with that, but I guess I'm only doing 22/26 in town. I dont check it because my speedo is not accurate, but we have the satnav when we go away. Its a series, running a 4-speed and OD, rangy diffs and 7.50's. Check it against the gearing caluclator and see what you come up with. Quote Link to comment Share on other sites More sharing options...
JST Posted November 11, 2011 Share Posted November 11, 2011 From what I've heard, Disco 200Tdi engines seem to do worse MPG than Defender ones. my experience is the opposite, my disco 200 regularly did more mpg than my gen 200tdi aboiut 10% more on a like for like trip all things considered. Quote Link to comment Share on other sites More sharing options...
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