[gav2612]

Hi all,
Have just bought a 2005 1.9tdi 130 Passat B5 as a runabout. After replacing numerous bits and pieces to get it up to scratch(wish I wasn't so fussy sometimes) It seems to be running pretty well. The fuel computer however is reading miles out on the low side. From the computer I am getting 35-37Mpg on the last three fill ups. It was zero'd at each fill up. By doing a full to full calculation however I got 46mpg, 41mpg and 43mpg (UK gallons) on the last 3 fill ups, not as good as my 47-50Mpg from my old A3 110tdi, but passable all the same. Does anyone know how the fuel computer calculates its MPG? does it use airflow, could the MAF be faulty causing this reading? Every other car I have had before read on the high side in MPG so trying to understand this

 

[chittychittybangbang]

Quick question, is it a mk4 (b5) or mk5 (b6) body style? The mk5 you can adjust the mpg computer. We only had Jetta available with TDI but you can use the mk5 DIY list if you have that type. See here: http://www.myturbodiesel.com/1000q/a5/inaccurate-fuel-economy-gauge-VW.htm

If you have a mk4 I don't think they had that option.

 

[gav2612]

Thanks for the Reply. B5.5 bodystyle I think. Facelifted version of the Passat available from 1997 on rather than the newer style B6. have VCDS, so will try the procedure listed in the link to resolve
Many thanks
Gavin

 

[chittychittybangbang]

OK, that article is only for mk6 B6. The electronics are totally different so those steps won't work. There may be another menu I don't know of though.

 

[Adamgolf]

Are you measuring the amount added at the pump? Some pumps can fill a little more or less than others. Try to be consistent with which pump you use.