disco TDI fuel consumption

shane hopwood · Jul 26, 2011

Hello out there again.

Just a question about the fuel consumption for my 1995 disco TDI.
Obviously everyone is looking at saving on fuel costs but it is only recently that i have given it much thought.[ mainly due to a mate having a v8]. Upon doing the obligatory mpg check that i was concerned to work out that the truck had only achieved 14 mpg ! Some mistake surely. So over the next 10 fillups i took mileage and gallons used figures, and achieved a low of 13mpg and a high of 17mpg.
The vehicle is standard save a 2" lift and 235/85/16 tyres.
The truck is used for heavy towing but not all the time.
The truck is regularly sericed with quality oil and parts. 140k miles

My question is, what may be causing this? and what other items should be checked. The truck runs fine. The power is down on what it used to be but hey its a 16yr old truck.

I dont want extra anything, but trying to achieve something close to original mpg/power would be nice

Cheer out there

rollin danny · Jul 26, 2011

Thats not right . Have you blanked egr and got rid of the cat.

shane hopwood · Jul 26, 2011

No, engine is standard, but surely those items would not make that much difference.

thebiglad · Jul 26, 2011

shane hopwood said:
Hello out there again.

Just a question about the fuel consumption for my 1995 disco TDI.
Obviously everyone is looking at saving on fuel costs but it is only recently that i have given it much thought.[ mainly due to a mate having a v8]. Upon doing the obligatory mpg check that i was concerned to work out that the truck had only achieved 14 mpg ! Some mistake surely. So over the next 10 fillups i took mileage and gallons used figures, and achieved a low of 13mpg and a high of 17mpg.
The vehicle is standard save a 2" lift and 235/85/16 tyres.
The truck is used for heavy towing but not all the time.
The truck is regularly sericed with quality oil and parts. 140k miles

My question is, what may be causing this? and what other items should be checked. The truck runs fine. The power is down on what it used to be but hey its a 16yr old truck.

I dont want extra anything, but trying to achieve something close to original mpg/power would be nice

Cheer out there

The tyres you have will affect the mileometer therefore your mpg calculations will be inaccurate - you will be doing approximately 10% more miles than you think.

Also these diesels are VERY air hungry so the first thing I would be doing is to change the air filter. Next I would be checking to see if the brakes are dragging.

The TDi 300's that I've have all have achieved overall plus de 30mpg. I have found that towing does not drag down the mpg.

14mpg is just atrocious for a TDi 300.

shane hopwood · Jul 26, 2011

Even taking the 10% difference into account i would be still well short of your mpg figures. Are ther any other "service" items that you keep in check that i might be missing that are outside of the usual bits and bobs, injectors maybe? Is DEGR worth doing?, i have never been convinced?

Dr_evil · Jul 26, 2011

If its air related hows the intercooler intake ? as well as the EGR pipe ? if thats clogged up you'll be getting buggered

thebiglad · Jul 26, 2011

shane hopwood said:
Even taking the 10% difference into account i would be still well short of your mpg figures. Are there any other "service" items that you keep in check that i might be missing that are outside of the usual bits and bobs, injectors maybe? Is DE-EGR worth doing?, i have never been convinced?

Hi Shane, when you are not towing how does the Disco drive?

You haven't said whether your car is a manual or auto box?

shane hopwood · Jul 26, 2011

The truck drives fine,It has definitley lost power over the last 12 mths but it is still ok i just have to use low box more than i used to although this is mainly when towing at low speeds. it is a manual.

thebiglad · Jul 26, 2011

shane hopwood said:
The truck drives fine,It has definitley lost power over the last 12 mths but it is still ok i just have to use low box more than i used to although this is mainly when towing at low speeds. it is a manual.

Reasons for loss of power that come to mind are:

1. Worn out lift pump

2. Muck in fuel sedimenter;

3. Leak in turbo hoses

4. Blocked or partially blocked inlet manifold

gregc · Jul 26, 2011

Check your intake pipes mate.
My top pipe had a tiny split in it and caused my mpg to about half it's normal and a massive power loss

davek0974 · Jul 26, 2011

To do that crap mpg it surely must be smoking like feck??

My 94 300tdi will do around 36mpg straight and 33 with a two ton trailer up it's arse.

To only get half the mpg you are using twice the fuel so should be getting twice the power(roughly speaking of course) as you say power is down, you may have a fuel leak.

I change air filters every three months or so but even that won't do much. If it's not smoking the fuel must be going elsewhere, on the floor or in the sump??

Dicovery maniac · Aug 2, 2011

have you checked the flip pump just changed mine todai as it was ****ing expensive diesel all over the places lol

disco TDI fuel consumption

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