Newbie here ,Quick question for the mechanically minded , my daughter bought a Landrover discovery 1999 td5 auto , about a year ago , she was using it for off road camping , the fuel economy is absolutely terrible , the engine seems to be running ok, any mechanics out there dare to have a guess at what may be wrong , i just bought a topdon OBD2 reader but haven't plugged it in yet to see if there is any faults stored in the ecu , the vehicle is structually sound and never been welded amazingly enough , was told at the time of purchase that it got a new head gasket ? the vehicle has been to the moon with star trek miles K250+ ,my daughter loves the dammed fing ! Q. would it be worth putting another engine in her or try to fix wot i got ? open to constuctive and helpful advice ....
Old Disco with really poor fuel economy
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Keith_L
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What do you consider to be "absolutely terrible"?
sierrafery
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First of all that OBD2 reader is useless, about the fuel economy there can be many reasons but quite unlikely the engine to be the problem as long as it starts and runs well... you need to plug in a proper Td5 compatible diagnostic tool to get some answers unless the vehicle is equipped with much bigger than standard tyres then that's the main reason
Henry_b
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My TD5 auto averaged low twenties and dipped in to the teens around town, I could get 28mpg on a run..
The autos aren't great on fuel, the loose converter that forces you to rev the bollocks off it doesn't help.
The autos aren't great on fuel, the loose converter that forces you to rev the bollocks off it doesn't help.
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+1 on that ^ sadly.My TD5 auto averaged low twenties and dipped in to the teens around town, I could get 28mpg on a run..
The autos aren't great on fuel, the loose converter that forces you to rev the bollocks off it doesn't help.
sierrafery
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So you butted in here just to blame the engine which we like? not a good ideea
Welcome to LZ.
All LRs like any other large 4x4 have crap fuel economy, pretty much half that of any normal diesel car.
low 20's on a long run , engine seems gutless as well tbh ( really have to put the foot down to get her to move ) ..She really only uses it for off-road camping ( Tent on roof ) which it does the job but that fuel economy is serious imo ...I never owned a disco myself or indeed a land rover / range rover so really don't know if this is normal but compared to the 4x4's i have owned ( i usually got around 30/35mpg on a long run ) the Disco's mpg seems excessive ?..
Many thx for the reply ,I know little or nothing about these 4x4's, i drive an old Gen 6 duel wheel transit van for work and it gets great mileage compared to the Landy but then again it is a manual , always thought that automatics were harder on fuel anyways tbh ..My old manual X5 bmw is also fairly reasonable on fuel in comparison .. Price you pay i s'pose for a bit of comfort , some guys are saying that the TD5's with the auto boxes are thirsty , as you say it must just be the case !
Henry_b
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Yep a thirsty beast, twas only 1-2mpg better than the 4.6 in my p38.. 
The older 4 speed gearbox is a pretty inefficient device, it was rubbish on the previous 300tdi engine, and it was still rubbish on the td5.
Low 20s on a run would be normal for a td5 auto.
Keith_L
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That sounds about right. Over about 8,000 miles my auto has averaged just under 23mpg. The car is quite heavy with the aerodynamics of a brick, and roof tents etc. only make it worse.
I had a remap to 165 BHP and 350 Nm, along with the Ashcroft 'medium' torque convertor and it transformed the drive.
Maat
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Mine got about 23mpg on a long run, at best. Td5 auto, straight piped with big tyres as well, so I would say relevant. I don't think it could've gotten any better than that.
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The roof tent will seriously affect it.
In locked up top doing about 55 mph it'll be at about 2000 revs which is peak torque so the most economical combination of speed (joke) and economy.
But you don't buy an auto 4x4 for economy.
And if the engine is old it will be worn and that won't help.
A good service, new filters especially air and a clean of the sensors, particularly the Map/Iat, and maybe unplugging the MAF might help a bit.
You could also change the ATF and the filter in the box too.
In locked up top doing about 55 mph it'll be at about 2000 revs which is peak torque so the most economical combination of speed (joke) and economy.
But you don't buy an auto 4x4 for economy.
And if the engine is old it will be worn and that won't help.
A good service, new filters especially air and a clean of the sensors, particularly the Map/Iat, and maybe unplugging the MAF might help a bit.
You could also change the ATF and the filter in the box too.
