I also had a breakdown this long weekend… drove the car up north to a buddies cottage, car started to misfire pretty bad checked with VCDS and it was cyl #4… to I stayed out of boost for as much of the drive as possible and started to diagnose the next morning.
Swapped ICM plugs, no difference.
Swapped coils and boots for Cyl #4 and 5… after doing that I blew up the coil that went into position #4:
So I drive back home with my buddies car (2.25 hours one way) get some extra coil packs and ICM’s and drive all the way back. Since we figured it was possibly an ICM (not thinking that a dead ICM shouldn’t really cause a coil to melt) we swapped them both out (ICM) and put in a new coil… Start the car, car runs perfect… sweet so button everything up, try again just in case car is once again missing.
So now what… good thing my buddy @ the cottage had some tools there… started to poke around with a multimeter and the schematics open on my laptop tracing the ignition circuit… what do we find? A damn short to GND on the trigger wire from the ICM to the coil for cyl #4 (pin 1 @ the coil)… I guess the wire must have broke completely when I swapped the #4 and #5 coils…
Looking @ this 10+ year old engine hardness it’s easy to see why this happened, the wire is very stiff and brittle and this situation will probably only start to get worse and worse. Time to look for a new harness! In the mean time we ran an overlay from the ICM plug to the coil plug and all is well right now.
Crazy weekend though!