Driving along quite happily today with no apparent problems then all of a sudden the car started to stutter power-wise when coming on boost at around 2500rpm. The car initially would seem to spool up then stutter, and then be OK again. When stopped and at idle the revs start to drop almost to a stall then the car recovers and brings the revs back to a normal level

To make matters worse it started to misfire which instantly made me think coil packs, and then on the way home to diagnose it appears to have lost almost all boost. You can still hear the turbo spooling slightly as well as the dv but it is all very quiet and there is next to no power. The dv and turbo have made no odd noises before hand which makes me think nothing too serious has gone but again you never know!

Got home and noticed burning smell from exhaust, possibly un-burnt fuel but I'm not sure. Popped the engine cover off to find the coil pack on Cylinder 3 had moved up about 1cm from the head. This has occured before and caused poor running so I assumed that re-inserting it properly would solve the issue. No luck though with the coil pack as it seems to be exactly the same with the coil pushed back down. There is no engine management light on at all and unplugging the MAF makes no difference (The MAF is also only about 4 months old). I also visually checked the hoses to see if any have come loose but cannot see anything like the usual suspects of the Pancake pipe or the Throttle Hose and no obvious splits.

I guess my next step will be to get the car checked with VAG-COM and see what errors may be flagged. Would it be fair to assume that this is likely to be a failed coil pack or could I be looking at something much more serious?

Edited 10 January, 201016 yr by Jon_VRS

Sounds like a coil pack.

if a coilpack is popping then you need to check the torque of the sparkplugs. if they are not in properly they will cause the coilpack to pop. This will also cause a missfire as the cylinder pressures will be wrong.

you may have a duff N75 or a bad vac line to it or the DV. If it was a popped boost hose you would be able to hear the leaking air from it.

The first three coil packs are still the originals. Probably not to bad on a remapped car at 80k as only one pack has failed before and been replaced. Strange though as when it went before I had a flashing EML and misfiring like mad, I assume the car has now entered limp mode and the coil pack is working well enough in this mode to not produce any more misfires.

I shall ask my local garage to check the spark plugs and also to give the car a service as this is due hopefully also will be able to sort this issue out.

Edited 10 January, 201016 yr by Jon_VRS

Well the car was driven over to the garage with no boost to begin with then half way there the car was all normal! Typical.

At the garage (APD near Poole) the car showed no faults and the spark plugs were then checked. Also got another coil pack to test and replaced the one that popped up to see if this makes any difference.