Poor Fuel Eco on TD5

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Update bAck from Paris full tank till light then refill wAs 77l and I did 414 miles that's 24.5 mpg not that impressed I stuck to 70 on the cruise all the way and no real traffic. I did however have 4 adults 2 kids and a roof box on so that might have affected it a little but should not have affected it too much.

Let me know what you think and if you think I have a problem
 
brainboy81 said:
Update bAck from Paris full tank till light then refill wAs 77l and I did 414 miles that's 24.5 mpg not that impressed I stuck to 70 on the cruise all the way and no real traffic. I did however have 4 adults 2 kids and a roof box on so that might have affected it a little but should not have affected it too much.

Let me know what you think and if you think I have a problem
Click to expand...


The roofbox will raise your consumption a bit but to be honest 24.5mpg on a run like that does not sound good at all to me.

I get 29mpg from my TD5 auto in mixed driving conditions, so I would expect you to get much nearer to that even with the roofbox on.

Are you confident that you did the brim to brim thing seeing the level of liquid, so that the calculation is accurate?

I would be looking at a new air filter imediately. Foolowed by a tyre pressure check. LR say something like 26psi at the front and 36psi iirc at the back. IMO the front is too low, I run mine at 32/36.

Mine has a K&N filter, De-EGR'd and now de-catted, which I must say improves performace therefore economy, significantly. I'll be doing another run to my sisters at the beginning of March so that will be 1,000kms and a good test.
 
Hi there,

Do you brim the tank at the end of a long run or before you set off? I always fill the tank till the hose cuts off. I've found that if the tank is hot, don't forget fuel goes back to the tank at a hell of a temperature in a TD5, then you can't get as much in.

If I fill up when hot after previously filling cold I think I've done brilliantly but if I fill cold after previously filling hot I think my mpg is rubbish. Per tank is not easy to work out accurate mpg. You need to average over 3 or 4 tankfulls.

I reckon I'm averaging about 530- 550 per tank when the light comes on.

Regards
 
6 people a roof box and the current climate (cold) wont be helping your fuel consumption, also if it is an auto that will drink more too. from what I am told a roof box can knock your consumption by 2-3mpg and if you include that with the extra weight you wont be far off.

What tyres are you running about on? there are peeps on here that say mt's will increase consumption by up to 3 - 4 mpg. Based on that at's should have a small effect too compared to road bias tyres.
 
Thanks for all the replies it's a manual running road tyres. Def brim to brim test did 414 on 77 litres got the car new years day and dis full service including air filter. Also I have removed egr. Looking at de cat next how much are they? Does it make that much difference?

Any other ideas on what can cause poor fuel I was expecting nearer 30 mpg on a run like I did. As I said stuck cruise on at 70 all the way and no traffic basically did not stop on the French side.
 
brainboy81 said:
Thanks for all the replies it's a manual running road tyres. Def brim to brim test did 414 on 77 litres got the car new years day and dis full service including air filter. Also I have removed egr. Looking at de cat next how much are they? Does it make that much difference?

Any other ideas on what can cause poor fuel I was expecting nearer 30 mpg on a run like I did. As I said stuck cruise on at 70 all the way and no traffic basically did not stop on the French side.
Click to expand...


Re De-cat pipe, I've just done this on mine and I can tell you that mine is running easier, more forward bound, needing to use less pedal so that should signify better mpg.

I bought mine from MM4x4 at Worcester for £61, but check prices on Ebay. Easy job to do yourself (I can say that now that I have done it!!) but I would offer the following advice:

1. Buy yourself a 6 sided 10mm socket, the one that drives on the faces of the bolt, not the edges;

2. Remove both crossmembers (so 16 bolts all the same 10mm size);

I reckon if I were to do another it would take about 1 hr, but I cannot stress too highly the need for this special socket - it made the world of difference doing the job.

Poor MPG - I have found that on long runs I used to use the cruise control but used more fuel. I think this is because you have told 'the computer' to keep the car at eg 70mph, so it does that no matter how throttle is needed to achieve that goal, especially up long hills.

If I drive without cruise and approach a long upward hill, I will build up speed before the hill so I don't need to bury the throttle half way up.

I'm hoping that the de-catt mod will improve mpg, I have done this mod on several previous TDi's and all improved by about 3mpg.
 
thebiglad said:
Re De-cat pipe, I've just done this on mine and I can tell you that mine is running easier, more forward bound, needing to use less pedal so that should signify better mpg.

I bought mine from MM4x4 at Worcester for £61, but check prices on Ebay. Easy job to do yourself (I can say that now that I have done it!!) but I would offer the following advice:

1. Buy yourself a 6 sided 10mm socket, the one that drives on the faces of the bolt, not the edges;

2. Remove both crossmembers (so 16 bolts all the same 10mm size);

I reckon if I were to do another it would take about 1 hr, but I cannot stress too highly the need for this special socket - it made the world of difference doing the job.

Poor MPG - I have found that on long runs I used to use the cruise control but used more fuel. I think this is because you have told 'the computer' to keep the car at eg 70mph, so it does that no matter how throttle is needed to achieve that goal, especially up long hills.

If I drive without cruise and approach a long upward hill, I will build up speed before the hill so I don't need to bury the throttle half way up.

I'm hoping that the de-catt mod will improve mpg, I have done this mod on several previous TDi's and all improved by about 3mpg.
Click to expand...

Thanks

ebay de cats seem about the £90 mark, so on the expensive side, i'm just trying to acheive the best mpg possible for th car, i would have like to see 500 miles per tank on mixed drving would be really happy with that.
 
brainboy81 said:
Tyres were inflated and checked befor ethe run to the book so 30 psi and 46 rear for full freighted run.
Click to expand...



I run the fronts on mine at 32psi all the time, so I reckon yours were a bit on the low side for a fully loaded up Discovery.

And yes, I know what the book says....................
 
thebiglad said:
I run the fronts on mine at 32psi all the time, so I reckon yours were a bit on the low side for a fully loaded up Discovery.

And yes, I know what the book says....................
Click to expand...

I did think 30 was a little low considering you go from 30 to 26 in the rear for a full load, what you running in the rear for a normal everyday usage?
 
Just adding my two-penneth.

I have had my TD5 from new (now 8 years, 160000 miles). Completely standard apart from a few accessories - still original exhaust, and still got EGR.

Overall I get 31 mpg. Can be up to 34 mpg in summer, on a run. 28/29 mpg when commuting or towing.

I use 30 psi front, and 40 psi rear. Running AT2 tyres.

Better in summer (presumably less time on a cold engine, and fewer electrical items (wipers, lights) running). Worse in winter.

Just serviced, with a new air filter, now with slightly warmer weather and less electrical items running should start to get better again...
 
MartinK said:
Just adding my two-penneth.

I have had my TD5 from new (now 8 years, 160000 miles). Completely standard apart from a few accessories - still original exhaust, and still got EGR.

Overall I get 31 mpg. Can be up to 34 mpg in summer, on a run. 28/29 mpg when commuting or towing.

I use 30 psi front, and 40 psi rear. Running AT2 tyres.

Better in summer (presumably less time on a cold engine, and fewer electrical items (wipers, lights) running). Worse in winter.

Just serviced, with a new air filter, now with slightly warmer weather and less electrical items running should start to get better again...
Click to expand...


Thats the sort of mpg i was expecting arounf 30 average, i only tow in the summer as i have a trailer tent and occassionaly a dump run with my little dump trailer but nothign majour my average drivign is good mix of a roads and a little town no real heavy town driving.

Done EGR and full service. maybe a pattern air filter is crap, i'm going to get the 5 alive performance air filter and decat pipe after pay day and then the iontercooler and a remap.

But if oyu are getting that mpg i must have a problem
 
brainboy81 said:
I did think 30 was a little low considering you go from 30 to 26 in the rear for a full load, what you running in the rear for a normal everyday usage?
Click to expand...


Right, tyre pressures, the book says 1.9/2.6 bar for normal driving, that would equate to about 26/36 psi. I think that is a setting to ensure comfort rather than max stability and economy.

I run 2.2/2.6 bar for normal driving and 2.5/3.0 bar for towing and /or heavily loaded. I find these settings comfortable, do not adversely affect tyre wear and are entirely compatible with a 2200kgs vehicle.
 
brainboy81 said:
Thanks for all the replies it's a manual running road tyres. Def brim to brim test did 414 on 77 litres got the car new years day and dis full service including air filter. Also I have removed egr. Looking at de cat next how much are they? Does it make that much difference?

Any other ideas on what can cause poor fuel I was expecting nearer 30 mpg on a run like I did. As I said stuck cruise on at 70 all the way and no traffic basically did not stop on the French side.
Click to expand...
70 is a bit fast, especially with a roof box. I find I get 33mpg at 60, but if I let it edge up it goes down quite quickly. With that load on you should make sure your rear tyres are pumped up to high pressure as per LR spec. I find that mine gives better mpg on French diesel - I suspect it has a higher cetane spec, possibly due to higher bio content. I notice for example that they sometimes do two grades - car and truck (cheaper).
Mine's an auto, and the mpg is 33 on a long run at 60, 23 if I drive it like a car - ie around town or at 80 on motorway.
I do think that anything on the roof will really penalise you at speeds over 60.
 
PASTMASTER said:
70 is a bit fast, especially with a roof box. I find I get 33mpg at 60, but if I let it edge up it goes down quite quickly. With that load on you should make sure your rear tyres are pumped up to high pressure as per LR spec. I find that mine gives better mpg on French diesel - I suspect it has a higher cetane spec, possibly due to higher bio content. I notice for example that they sometimes do two grades - car and truck (cheaper).
Mine's an auto, and the mpg is 33 on a long run at 60, 23 if I drive it like a car - ie around town or at 80 on motorway.
I do think that anything on the roof will really penalise you at speeds over 60.
Click to expand...


I agree that due to the aerodynamics of a Discovery, 60mph has an mpg advantage over 70, however, I run an autobox model and if on motorways cruising at 60-ish and confronted with a long hill, you are not in the optimum rev range to climb that hill and you can get too close the threshold of Torque Converter lock-up, whereas at 70mph you are better placed.

Incidently having tried both approaches of with and without cruise control, I find it more economical to run without.
 
thebiglad said:
I agree that due to the aerodynamics of a Discovery, 60mph has an mpg advantage over 70, however, I run an autobox model and if on motorways cruising at 60-ish and confronted with a long hill, you are not in the optimum rev range to climb that hill and you can get too close the threshold of Torque Converter lock-up, whereas at 70mph you are better placed.

Incidently having tried both approaches of with and without cruise control, I find it more economical to run without.
Click to expand...

Ok so in future try with out cruise i was coming off it for ome of the longer hills and i have manual.

But still does not explain why i'm only getting 24 on a run like that surely not everyone drives around at 60?
 
brainboy81 said:
Ok so in future try with out cruise i was coming off it for ome of the longer hills and i have manual.

But still does not explain why i'm only getting 24 on a run like that surely not everyone drives around at 60?
Click to expand...


I still think there is something amiss with your vehicle, but the key to a successful resolution is proper effective diagnosis. You need to get your car connected to an electronic diagnosis machine, with the engine running, so that each sensor can be interrogated to access it's values.

Have a look here to see if any of these guys could help you, they are all NanoCom owners:

www.discovery2.co.uk/ Nanocom Locator, get help from your Land Rover Buddies!!!

Good luck

Dave

Ps Can't remember if you have already said but, have you cleaned the MAP sensor on the inlet manifold and have you changed the air filter?
 
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