Misfires after 2 hrs motorway driving

[HSPartner]

Audi 3.0 Avant (2002) - intermittent fault where engine misfires and loses much power after 1.5 to 2 hrs of steady motorway driving.

I can continue on the journey by trying to avoid accleration or decceleration and keeping revs steady (and dropping to fifth gear to keep revs steady) plus by making regular stops (cooling the engine for 30 minutes seems to help!).

Engine management warning light flashes and then remains lit. The following day there is no recorded fault left on system.

The local Audi dealership have had made several attempts to diagnose the problem without success and have seen the behaviour in the workshop.

A long trip also drains the battery and it has now blown the starter motor. Plus a catalytic convertor has already been replaced!

[Sky]

Right up my street this one. All smacks of modern kit not keeping up with essential mechanics. I'll bet me bottom dollar on a dodgy earth... No; honest, first place I would look. Find em all, unbolt/unscrew, clean and refit. Look for any signs of arcing or black oily deposits (loose connection). Look at the facts, increasing heat = increased resistance = point of no return. Good huntin' old chap. Top tip, run the B*gg*r till it plays up in a dark spot and keep the lights off. Dont look directly at the engine cos your eyes are more sensitive off to one side and watch for blue tinges. You'll be amazed at what you see sometimes.

ps I would start with the battery leads before all else and have the battery checked under load...

Best of British/German

[RickT]

Your best getting onto VAG-COM and check whats going on... more than likley it will be a dodgy coil pack... £25 each to replace..

RicKT