I have 2010 A4 B8K 3.0Tdi Quattro Avant. It has done 110K miles, and in the last week or so has started light intermittent misfiring under load when most usually within the first 10 minutes of a start from cold. It has not brought up the engine management light but when I use my Carista diagnostic tool, it brings up a code 07901 which my local garage cannot find in his fault code manuals and the local Audi dealer say they cannot find unless I book it in with them for a diagnostic session (and charge for it!). I am concerned because my previous A4 B7 3.0Tdi Quattro Avant started doing the same thing at 240K and eventually got so bad that the engine kept cutting out with clouds of smoke, and on that car, when Audi did a compression test, they said I only had one cylinder that was up to the minimum pressure of 19bar although my local garage considered that the engine would not have even started if the pressures were as low as they claimed. On that car, we tried everything from changing ECUs to changing injectors but always the car would run fine for a couple of days, sometimes a couple of weeks and then suddenly the fault would come back with a vengeance. I thought it was just an unfortunate problem with the previous car but with the same problem appearing on this second car with ostensibly the same engine, I'm rapidly losing faith in the 3.0Tdi engine.
Help Please slight misfiring under load and unknown fault code
- Thread starter Martin Watson
- Start date
I'm thinking that at perhaps 110k it might be the valves choked up and not seating properly and covered in black gunge, my old 3.0 a4 had 80k on the clock and was a mess on the inside.
Just a thought, but am definitely no engine expert.
Wish I took close up pics of the valves as they were worse. But the inlet gives you an idea.
Just a thought, but am definitely no engine expert.
Wish I took close up pics of the valves as they were worse. But the inlet gives you an idea.
https://www.audi-sport.net/xf/threa...-egr-cleaning-refurbishment-help-info.209076/
Not sure on the mileage on this V6 but there is no way an engine will be running good looking like this.
Not sure on the mileage on this V6 but there is no way an engine will be running good looking like this.
I had the engine Terracleaned in the summer so I would expect it to be reasonably clean now. I don't dawdle when I drive or do short journeys, always at least 30 minutes of reasonably rapid driving ( I live in the country so no traffic jambs or idling in long queues) so it doesn't get much chance of coking up. I always use good quality fuel, not low-grade cheap fuel. I do about 20K miles a year so it's not sitting around doing nothing, it gets used every day and I get it serviced at the regular intervals, albeit it uses longlife oil so service intervals are 18~20K. I changed one of the EGR sensors a month back because it was faulty and kept bringing up the flashing glow plug warning and my Carista device said it was that particular sensor. I haven't had that problem since.
- Joined
- Feb 10, 2016
- Messages
- 196
- Reaction score
- 43
- Points
- 28
I don't find my Carista very good for picking up manufacturer specific codes at all, and sometimes gives irrelevant information.
Where as my VCDS or Snap on code reader gives much better information.
Can you get it re read locally using another tool? Does sound EGR like though initially
Where as my VCDS or Snap on code reader gives much better information.
Can you get it re read locally using another tool? Does sound EGR like though initially
Terra clean dosen't clean any of the inlet manifolds and doesn't do much in the way of cleaning the EGR so i would recommend having them manually cleaned
