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View Full Version : 1.4 TDi 90, poor fuel economy problem



Cloth Ears
28-12-2009, 07:47 PM
Hi,

I have an A2 1.4 TDi 90 Sport (with the 17" wheels), which I love. I've had it from nearly-new and done about 45,000 miles in it. Over that time, the average MPG has been about 50-52 mpg in mixed motoring with plenty of town and rush-hour traffic. (Mileage checked by brimming the tank and noting the mileage for each refill). The trip computer usually reads slightly optimistically, at about 52-55 mpg average. On longer motorway runs, I have more than once managed a trip computer average of 69mph and 59.9 mpg simultaneously, which I thought was pretty impressive. Once, on a leisurely holiday pottering around the Cotswolds, we averaged 69mpg for a whole tankful.

So, I'm reasonably confident that the car is pretty economical, as a rule.

Unfortunately, for the last 6 months, the mpg has been getting worse. Now, we struggle to get 44 mpg average on the trip computer, even on trips which would previously have shown figures in the upper 50s. It's not a trip computer fault as we get proportionately less miles between refills as well.

The only thing that has changed is that I changed the standard Michelin front tyres from 205/40 ZR17 to 205/45 VR17 Avons. This has massively improved the ride, like you wouldn't believe, and I'd be VERY reluctant to go back to the previous tyres.

I don't think the tyres can be completely to blame, though. I might have expected a couple of mpg drop due to the gearing changes (though on a motorway run, they might also have improved for the same reason) and also the softer compound. More importantly, the mpg has continued to get worse but if it was all down to the gearing, it should have improved again as the tyres wore down.

At first, we nticed that the car average had dropped below 50mpg, then it dropped below 48, and I mentioned it when the cambelt was changed. The dealer found no fault codes, so I don't think there is anything seriously wrong. It has continued to get worse, now it takes about 30 miles out of a full tank before the average mpg gets out of the upper 30s, and I simply can't get it to go higher than 46mpg at best. Current average is about 44 mpg overall.

The Audi main dealer which services the car has drawn a blank, though they have assured me that there is nothing seriously (and expensively) wrong. They seem to think the mpg is in the normal range, though my experience over the last 45000 miles would seem to differ.

Any ideas, out there?

Thanks, in advance

Steve.

Cloth Ears
03-01-2010, 02:09 PM
Update:

Car went 'bang' on a fast dual carriageway on 29 December. Sudden loss of power, struggled to maintain 55-60mph. Lots of smoke from exhaust and, by the time I found somewhere safe to stop, a clattering sound from under the bonnet.

Waiting for a verdict from the dealer. Expecting a large bill. :zx11:

Crasher
03-01-2010, 03:16 PM
Sorry to hear that, keep us posted.

Cloth Ears
16-01-2010, 10:28 AM
It's turbo failure. The dealer has quoted me a little over £2000 to have it replaced, not including replacement of the cat, and not including any other repair work that might be needed when they get it apart.

I asked if Audi would be willing to make a goodwill contribution to the cost, on the grounds that:

a) The car has always been maintained in excess of the Audi schedule, by the main dealer. It has covered only 48,000 miles since new and is just over 5 years old.
b) everybody is telling me how rare this is, and how unlucky I have been, so presumably a fair subsidy, say 25-35%, from Audi to a good customer wouldn't bankrupt them.

This request has been declined by Audi customer service. I asked them if they would mind explaining why. They said they would get back to me the same afternoon. That was two days ago and I've not heard a word since. The dealer, to their credit, seems a bit embarrassed that they can't help, and has been extremely helpful about the use of a courtesy car during the investigation and negotiations with Audi.

The car is now with a specialist who comes highly recommended, and who has quoted me less for the job than I would have been prepared to pay Audi, if they had made a contribution. If they do as good a job as I've been led to expect, I'll name them when I get the car back.

Crasher
16-01-2010, 02:35 PM
I hope they do an awesome job.

Cloth Ears
16-01-2010, 03:18 PM
I hope they do an awesome job.

I've just been down to see them to talk about the work and, yes, I think there is a very good chance they'll do an awesome job. In which case, they'll get the opportunity to give it an awesome service on a regular basis, too.

Cloth Ears
25-01-2010, 06:33 PM
I've just picked the car up from Awesome GTi. Good as new and £800 cheaper than the quote from Audi, for a very careful and thorough job.

Top blokes, excellent service. Another happy customer!

Crasher
26-01-2010, 12:00 AM
Result!

wid77
26-01-2010, 08:46 PM
I've just been down to see them to talk about the work and, yes, I think there is a very good chance they'll do an awesome job. In which case, they'll get the opportunity to give it an awesome service on a regular basis, too.

Good to hear you got it all sorted out. I would always go with a good independent garage rather than a main dealer myself. So, is your mpg back up to what it was? Do you think the drop in efficiency was due to the turbo not working properly?

Cloth Ears
27-01-2010, 08:09 PM
I've only done about 50 miles since getting the car back, and that's been fairly gentle driving, but no, the fuel economy problem doesn't seem to have been solved. At the moment, the mpg is hovering around 48-49 mpg (indicated) where I might have expected to get about 55 mpg driven as gently as it has been for the last 50 miles or so.

It's early days, and it might change a little when the turbo is broken in and I use it normally, but I think it might need a little more attention. The guys at Awesome seem to think there are a few things worth checking-out, which is more than the dealer seemed to be able to offer. As far as they were concerned, if there was no fault code in the diagnostics record, there was nothing wrong with the car.

micheal balbrig
28-01-2010, 11:05 PM
I've only done about 50 miles since getting the car back, and that's been fairly gentle driving, but no, the fuel economy problem doesn't seem to have been solved. At the moment, the mpg is hovering around 48-49 mpg (indicated) where I might have expected to get about 55 mpg driven as gently as it has been for the last 50 miles or so.

It's early days, and it might change a little when the turbo is broken in and I use it normally, but I think it might need a little more attention. The guys at Awesome seem to think there are a few things worth checking-out, which is more than the dealer seemed to be able to offer. As far as they were concerned, if there was no fault code in the diagnostics record, there was nothing wrong with the car.

I think the reason for loss of MPG in some cases is that the oil companies
mix bio diesel with their fuel with a resultant drop in MPG figures
This is only an opinion and may be incorrect. I drive a vw caddy for my
job which gave 42- 44 MPG These figures dropped to 36-38 MPG over a
period of 3 years

Cloth Ears
07-02-2010, 06:19 PM
The economy problem has not been cured by the new turbo, and is way worse than can be accounted for by differences in tyres, fuel types or whatever.

Yesterday, the car went into limp-home mode and the emissions control light came on. I'll have to get it back to Awesome GTi, see what they make of it. I do hope this latest problem, and the fuel economy issues are related, otherwise I've now got two things still to fix.

wid77
07-02-2010, 09:06 PM
Good luck with getting it sorted out. I know how frustrating it can be when you have a car problem you can't fix. Maybe reading the fault codes will indicate the problem?

tomandjo2
08-02-2010, 01:42 PM
Economy can also be greatly effected by cold weather, deisels don't seem to generate as much heat as petrol engines and if temps are very low and you have your heater on it my struggle to maintain normal running temperature so ECU will run fuel a bit richer.

Although it would appear your issue is a more serious one.

Are you using SHell V power fuel?? if you are change to normal deisel
Tom

Goorgiel
17-09-2012, 10:04 AM
Hi

I have picked up the exact same issue on my Polo 1.4TDi, I have been getting around 750km - 780km for the last 2 fill ups where I used to get on average 880km - 950km. The car's meter shows that I'm still doing 5.4 l/100km but the fuel needle is still dropping. The Turbo has been replaced 20 000km back plus the car had a service 4000km back. The only thing that was changed before the bad fuel usage was brake pads, not sure if they will have an affect?

Crasher
17-09-2012, 12:01 PM
Get it code read first, if there are no codes, check the air filter for blockages and if that is OK, replace the Air Mass Meter with a genuine VW one as a starting point. You would be better served by starting your own new thread with the cars year and engine code.