Reduced MPG?

[Paddyd101]

Hi All,

First time poster

I recently bought a 2002 A4 Avant 1.9tdi sport 130bhp. The Thermostat was faulty and the temperature gauge did not rise any further than 55 degrees. I was only averaging 40mpg, with 90% motorway driving. I was disappointed with this, so I replaced the thermostat. The temperature gauge now reaches 90 degrees when warm as I would have expected. However, It can fluctuate slightly from between 75-90 degrees even after a long period of time when warm, particularly if driving at slower speeds or stop/start driving like in the town. Is this normal? I was under the impression that with audi's/VW's once the temp reaches 90 degrees it stays there regardless.

My MPG has also improved from 40mpg to 48mpg. I would still like this to improve as I do mostly motorway driving. Any Suggestions?

 

[Cabbyfan]

I would check the actual temp sensor as well. If you do have to replace it use a genuine one.

 

[deano1978]

Hi.
Yes it should when warmed up(15mins of driving) sit at 90.
Try one of these...

http://pages.ebay.com/link/?nav=item.view&id=160907459162

50-60mph should get u over 50mpg

 

[DieselJake]

40-48mpg is good especially considering the weather, mines around 44 max although the bigger turbo and heavy right foot are responsible, mpg is mostly depicted by how you drive and I would take stats manufacturers claim with a pinch of salt.

 

[Paddyd101]

I should have mentioned, I have already also changed the coolant temperature sensor. I am very particular with regards how I drive to maximise fuel economy, ie no harsh acceleration/braking/gear change/ and I sit at 60 on motorway etc
Might the fuel temp sensor affect the fuel consumption? Anything else?
What else may be causing the fluctuation in the temp garage?
Thanks

 

[barkclark]

I've averaged 36-45mpg so far from my unmodified FWD 1.9TDi Avant. I think I'll get my thermostat and temp coolant sensor changed to see what happens. I to have been trying to maximise my mpg through my driving style. From what I've read on forums, I was expecting at least high 40's all day long!

 

[AudiLeon]

I have to ask. Were the thermostat and temp sensor genuine? Because I bought aftermarket and soon had to buy genuine.

 

[Paddyd101]

Both parts were aftermarket. Temp sensor was off ebay and thermostat was from eurocarparts. Foolish?

 

[bradh]

Yep I had euro state my car ran worse fitted genuine vw one was spot on after that

 

[Chrismawa]

Give your MAF a clean. Cleaned mine and I was amazed with the effect on MPG.