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ndamico

Td5 defender 15P poor mileage

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Hoping for some help.  Have 200kms on it. Seems to run great but get about 16mpg max.  I'm new to the td5 so here is how its setup,  some of which I know doesnt help mileage.  I dont have a fast tune in it and dont hot rod the car. It's an overland vehicle so lots of trails and freeway stuff getting there. I usually run 70MPH on the freeway.  Any reason why the mileage is so poor?

 

Stock gears with Ashcroft lockers

1.4 tcase

35x12.50r17 maxxis razr MT

Exocage

2" lift

Ashcroft underdrive

BAS intercooler

MANN pro vent

Turbo technics VGT from BAS

Storm tuning

Egr removed

Cat removed

Stainless exhaust

82*C thermostat 

Nanocom

New fuel pump

New alternator

New silicone coolant hoses

New pressure regulator

new alternator

New injector harness

new water pump


 

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70 mph in a Defender on big MT tyres with an exterior cage in a chipped TD5 will not be economical on fuel. You've built a rock crawler not a long-distance tourer. 

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That’s true - but I’m getting 30.

I wonder if your map is throwing fuel at it.. ? 

 

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Assuming it’s standard Td5 gearing (gearbox and diffs) you should be doing about 2600 revs at 70mph - which seems comparable to a Td5 with smaller tyres and a 1.2 transfer box.

If you drive at 60mph what mpg are you getting.

 

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The difference between 60-65 mph on the motorway and 70 mph robs me of about 2-3 mpg. Wind resistance is the killer. Add on the silly big/knobbly tyres, lift, remap, extra weight and you’ll easily see sub-20 mpg.

I see also you’re in the US - 16 of your MPGs is just over 19 of ours, so bear that in mind when comparing with figures from the UK.

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3 hours ago, ndamico said:

Hoping for some help.  Have 200kms on it. Seems to run great but get about 16mpg max.  I'm new to the td5 so here is how its setup,  some of which I know doesnt help mileage.  I dont have a fast tune in it and dont hot rod the car. It's an overland vehicle so lots of trails and freeway stuff getting there. I usually run 70MPH on the freeway.  Any reason why the mileage is so poor?

You're in CA but using KM's?

Is that US gallons or Imperial for the mpg?

How are you actually working this out?

Either way it seems low. Have you checked for fuel leaks? 

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As said, that's equivalent to about 20mpg imperial - if thats an average over your fast road and off road fun you probably aren't seeing anything too unusual for a presumably heavy TD5 with a cage. Drop your speed down to 65 and you should see a difference. Running sub 28/40 psi tyre pressures front/rear with big MTs will knock a few mpg off also.

Diesel is significantly cheaper in the US so I guess you're not so used to stretching a gallon out as we are here? 

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Given the load you're lugging, paradoxically you may find you get better 'highway' mileage from driving in 4th rather than 5th.

An engine spinning freely at relatively-high RPM can be more thermally-efficient than one 'labouring' against a large load at low-revs. And, mechanically, the gearbox in 4th is 'straight through' with minimal friction whereas in 5th the intermediate-shaft is involved, which must mean extra power-wasting drag.

In my 90TD5 even when running 'light' I don't ever use 5th below 55MPH. The TD5 has BMW heritage - designed to rev!

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The TD5 doesn’t have any BMW heritage, it was designed before BMW took over. 

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16(US) MPG, wow, if you fit a V8 you MPG will probably go up!

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On 3/30/2020 at 5:57 PM, Tanuki said:

Given the load you're lugging, paradoxically you may find you get better 'highway' mileage from driving in 4th rather than 5th.

An engine spinning freely at relatively-high RPM can be more thermally-efficient than one 'labouring' against a large load at low-revs. And, mechanically, the gearbox in 4th is 'straight through' with minimal friction whereas in 5th the intermediate-shaft is involved, which must mean extra power-wasting drag.

In my 90TD5 even when running 'light' I don't ever use 5th below 55MPH. The TD5 has BMW heritage - designed to rev!

They said running at 70. You won’t be doing that in 4th!!

Td5 has as much to do with BMW as Ferrari does. 

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On 3/30/2020 at 12:30 PM, Eightpot said:

As said, that's equivalent to about 20mpg imperial - if thats an average over your fast road and off road fun you probably aren't seeing anything too unusual for a presumably heavy TD5 with a cage. Drop your speed down to 65 and you should see a difference. Running sub 28/40 psi tyre pressures front/rear with big MTs will knock a few mpg off also.

Diesel is significantly cheaper in the US so I guess you're not so used to stretching a gallon out as we are here? 

20mpg imperial from that setup as a mean average and not thrashing it. There is something not right at all. Fuel leak, poor map or calculating it and distance incorrectly. 

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I wonder about the mapping/performance upgrades, a lot of them just wind the fuel up or do awful bodges like fudging the air/coolant temperature sensor values to the ECU to make it throw more fuel in. If black smoke is coming out you're wasting fuel.

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Thus my comment above pondering if the map was just chucking fuel in to for power - I wonder if it smokes?

I wonder if the FPR is leaking?

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