Hi!  My 2003 A4 2.0 TFSI badly misfires either in very hot weather or after driving a long distance of around 40 miles but becomes ok as soon as it is re-fuelled. This seems to suggest a problem with the fuel system being affected by heat.Any idea what the particular problem could be please? It is so frustrating as it even sometimes stalls in such conditions when in slow traffic. Thanks!

Hello Robert,

Modern fuel is more volatile than it used to be, but the likelihood of fuel vapourisation should be able to be discounted on the age of car you have. 

On the basis of simple things first, I would be tempted to replace the fuel filter with a good make replacement, and see if that improves the situation. If it doesn’t, it could be worth renewing the fuel pump relay. 

Kind regards,

Gareth.