can anyone point me in the right direction, my a6 tdi has started to intermittantly misfire or judder, mainly when accelerating a bit harder, it also revs irratically now and again when i start the engine. To clear the judder i need to stop and switch the engine off then restart it and all is fine until the next time.

 

check your spark plugs. If you changed the plugs, the plug wires were probably brittle and fractured in various places throughout the line causing a bad connection. The simple solution for this would be a tune up, i.e. new plugs and cables. Also note: even if you didnt change plugs or anything like that brittle wire can still cause a bad connection. depending on the mileage of your car, you will most likely only need to do this particular tune up once or twice during your ownership of the car depending on how long you keep it. this may not be the actual problem but its the first thing that pops up in my opinion.

 

As you probably know, its not your spark plugs as you dont have any. I dont think its a glow plug issue either as a glow plug issue would clear itself up after cold start. The only issue ive seen with the tdi's in the us is air in the lines caused by plugged fuel filter or carbon buildup in the intake from the egr system. What kind of system is it? Is it a pump line and nozzle, or are there serperat injectors with wires going to them for each cylinder? Any faults?

 

I use diesel equipment all the time. Whilst there are differences between my Massy Fergeson tractor and an Audi tdi, there is a lot of overlap.

First, try different fuel. Might have a bit of h2o in your tank, which doesn't combust very well. Try a fuel conditioner. Is there a fuel/water seperator? If yes, empty it. Change your filters and pre-filters, esp if you're in a cold climate. They like to cake up this time of year.

If that doesn't produce improvement it is possible that there is an actual mechanical fault. Start at the injector pump. The problem is not air; that would cause a no-start condition, not a load-related miss. Is this a direct-injection setup? Not sure how that makes its pressure, but if we suspect that the pump isn't making enough pressure, then it's time for a trip to the stealer.

Odds are, however, that this is a fuel or fuel filter issue. We're using a 2% bio-diesel blend here in Minnesota and some people have reported issues, but I think that's b.s.. Problems don't begin until at least 20%. We're also in the middle of a change-over to low-sulpher diesel, so there may be some other supply issues.