I have a very annoying problem with lumpy tick over on my A4 Avant Tdi (130). I have had the injectors serviced / replaced and this has not altered the problem. The car has done about 91K miles and is a 52 (2002). The full characteristics are as follows:
  1. Is NOT lumpy when cold.
  2. Is lumpy once the engine is warm.
  3. Is not lumpy above about 1K rpm
  4. The lumpy running goes away if I force the air con to work hard (set temp to ‘lo’) and put HRW on.
  5. Apart from tick over, the power, mpg, smoothness in high revs is all fine.
It has been put on a diagnostic machine (NOT main dealer) and no problems showed up. I am a bit concerned about the cost of asking a main dealer to fix, without knowing any of the possibilities.
Could re-mapping sort it, or would that just be disguising the problem ?
All ideas and suggestion welcome