A6 poor fuel economy

[billy g]

Hi, just recently purchased an a6 2002 model, lovely looking car and drives fantasticly well, its a 130bhp 1.9tdi with a full service record of which i have all receipts for work done, very powerfull for such a big car. the one thing i'm disappointed about is the mpg, i expected it to be above forty's going back and forth to work etc but i'm only returning 33mpg, should it be better, car runs very well otherwise.

[cctuning]

It might be worth checking the egr valve or maf as it sounds a little low to me.

I had a customer a while ago who had a passat giving a similar kind of mpg figure and when the customer just removed the egr valve pipe he gained another 3 mpg and after that he replaced the egr and the mph went up to around 40 mpg, if I remember correctly.

[Dozy]

Hi

If it is the AWX engine then it is definitely low.

I had my professionaly re-mapped to 169bhp and stll get 46mpg on a mixture of commuting and 70mph motorway work.

I'm by no means an expert, but would suggest MAF and check all of the plumbing on the cold air side of the turbo for leaks. sounds like it is over-fuelling and if you're not getting the performance to match the fuel usage it may be worth looking for a smokey exhaust when engine is under load.

Also worth trying a dose of Forte diesel treatment in case injectors clogged and not giving a very good spray pattern.

Cheers

Dozy

[billy g]

It might be worth checking the egr valve or maf as it sounds a little low to me.

I had a customer a while ago who had a passat giving a similar kind of mpg figure and when the customer just removed the egr valve pipe he gained another 3 mpg and after that he replaced the egr and the mph went up to around 40 mpg, if I remember correctly.

thanks for the reply. will look more into that . thanks

[billy g]

hi, what is the significance of smokey exhaust when engine under load and what does engine under load mean?

[Dozy]

Smokey exhaust means not enough air being supplied from the turbo to burn all of the fuel completely. can sometimes be caused by a leak in the pipework from the turbo, via the intercooler, into the engine, or a sensor giving the ecu duff info as to how much fuel to squirt in for a given engine speed / throttle position. The end effect is the same : too much fuel being burned without the corresponding power being produced. If you remember bunsen burners from school, when the air hole is closed, for the same amount of gas going through it you get a cool yellow sooty flame instead of a nice hot blue flame when the air hole is opened.

A bit abstract maybe, but I hope you understand the principle.

Cheers

[billy g]

thanks for the explanation, easy to understand, took me back to science classes at school and the carry on we had with bunson burners lol, but hey thanks again dozy.cheers billy g.

Smokey exhaust means not enough air being supplied from the turbo to burn all of the fuel completely. can sometimes be caused by a leak in the pipework from the turbo, via the intercooler, into the engine, or a sensor giving the ecu duff info as to how much fuel to squirt in for a given engine speed / throttle position. The end effect is the same : too much fuel being burned without the corresponding power being produced. If you remember bunsen burners from school, when the air hole is closed, for the same amount of gas going through it you get a cool yellow sooty flame instead of a nice hot blue flame when the air hole is opened.

A bit abstract maybe, but I hope you understand the principle.

Cheers

[nigelbb]

33mpg? Luxury! I have a 2.7T (V6 2.7L twin turbo) & am lucky to get 23mpg:-(

[portovechios]

Does the temp get get up to 90? If not you'll find the Ecu cant map the best fuel delivery because the ecu will think it's cold and still warming up.

I'm no expert but i had the same problem with my A4 and Passat.

Changed the notorious temp sensor and stat for £32 including 1.5lt G12 ++ and voila, now 45mpg mixed driving

Money back in no time