Questions with my A4 Avant 2.5tdi Quattro - 2004


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Nov 6, 2005
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I have just brought the above car (I previously had a 1.9 tdi)

I filled the tank up on Sunday and DIS range is 340 miles - is this right?

Around town I only get low to mid 20's
On the motorway I get low to mid 30's

I know this is a bigger engine but I would have thought I would get better return than above (This car is standard and not modified).

The car also is nosier than my 1.9tdi (Below 2000rpm) and more whooshing sound when on the loud pedal. Is this normal for a 2.5tdi?

My old car did not smoke when putting my foot down, but this car has some smoke coming out when I plant my foot down. From the mirrors its very light grey and all the coolant, etc is ok.

Any help/advice much appreciated.
The 2.5 is indeed a thirsty beast unless you drive with real care. I don't do any town work or motorway work really so can't offer you any comparison figures. Mine achieves approx. 34-36 on rural A/B roads, so i would suggest your figures are a bit low.

Maybe you're driving it harder than average to enjoy the slug of torque and V6 roar? I've a tuning box fitted and it doesn't smoke at all (that I can see.)
thanks quattrojames.

I only noticed the smoke today when on the motorway. Car was around 1800rpm and doing around 65mph and I checked my rear view mirror and saw like a hazy smoke on the rear windscreen. Then down the motorway it was gone.

I have been driving it carefully but still can't get the figures up. What would cause this?
My DIS typically shows me 450 on a full tank. Poor consumption could be anyone of a number of things. How many miles has the car done?

If you're genuinely concerned it might be worth getting it scanned for error codes.
wow - 450mile!! I was getting that reading with my 1.9tdi.

Scanned the car - no errors.

Car has 59k on the clock with dealer full history.
I've got the 2.5 TDi FWD, this averages about 36 mpg motorway/town mix and anything upto 45 mpg if I'm on a long 70 mph motorway cruise. I do get smoke some times when I boot it, I would say this is standard for a 90k diesel. I've been told redex diesel additive can help although I have'nt tried it myself. A good thing to do is floor it a few times on the motorway and that will get rid of the soot in the exhaust system.
I think the mileage thing is something a lot of people have been caught out by with the 2.5tdi. It can be shockingly bad on some. There's those who say they get 45mpg on a run (which equates to 650miles to a tank)
Then there's a another group of 2.5tdi owners, myself included who have struggled to see 30mpg (450 miles to a tank) and that's trying hard before I fitted a tuning box.

I've seen much better readings since fitting a tuning box - 475miles to a tank average but that's still nowhere near 45mpg. (in fact, it's just under 33mpg)

Re: grey smoke - mine's on 118k and doesn't smoke enough for me to see from my rear window, though i'm told if I accelerate hard there's a slight bit of black smoke, like all diesels. Light grey smoke sounds like it could be condensation in the exhaust or something? Does it go after a while?

The V6 has sort of a whine at low down revs like sirens in the distance, but a whooshing sound might be split pipes somewhere. Actually come to think of it, i drove mine about 200yds once without an air filter. It whooshed, and smoked. Check your filter is in properly. Random guess but the symptoms match up.
cheers guys, will have a look at the air filter and I will buy some fuel treatment from Lion Garage.

The grey smoke is still there when the car is fully warmed up. Hopefully the fuel treatment will sort it out - the car has been sitting on the forecourt for a couple of weeks.
There is defo a split some where, when revving the car above 2000rpm you can hear air escaping from somewhere.

I have had a look and can't see any loose clips.

I have checked the hose to the tubro but that's ok.

Do the 2.5tdi have 2 intercoolers?
Yeh they do, this may help:

cheers for the picture.

Are there any common pipes that fail on the 2.5tdi?

I'm going to have a look on Saturday. I suspect there is split/loose pipe near the windscreen washer bottle because it recently had the headlamp washer pump replaced.
go on ebay and get yourself some forte diesel treatment its about a tenner it cleans and lubricates the entire fuel system both going in and coming out ie cleans the lamda sensor and cat its normally only available to the trade and most garages swear by it
cheers guys, will have a look at the air filter and I will buy some fuel treatment from Lion Garage.

The grey smoke is still there when the car is fully warmed up. Hopefully the fuel treatment will sort it out - the car has been sitting on the forecourt for a couple of weeks.
5 mile trip -

DIS was showing 240 miles. By the time I got home it dropped to 215 miles and the MPG dropped from 27ish to 19.
Also I could not feel the force of the turbo when putting my foot down. The whooshing sound is quite loud and anything over 2000rpm people walking down the street turn and look at the car :(


Cheers, I brought some Forte from Lion garage. Will put it in as soon as I know the pipes are ok


Cheers. Going to have a good look on tomorrow.

Also I have booked the car in with Lion Garage for Monday am. I can find the split then I will cancel the visit, if not it's going in on Monday.
mine made that wooshing noise and i located it to be the air box connection was slightlt misaligned, a quick wiggle on the pipes and it disappeared
Found the split hose!!!

Number 22 hose on the diagram is split on the top and you can see gunk/oil in that area.

Ordered new pipe - £49. Will be here tomorrow.
New pipe installed this morning - car performance, mpg is much better and there is no black smoke!!

The new pipe came complete with jubilee clips :)

Pictures of the split and new pipe -





It was a easy find James, I thought the split might be hidden away.

Happy days.