Continuation from my fault finding post above.
Spent a fair bit of time trying to diagnose the issue as the miss fire only happened when idling.
First ran VCDS to monitor the miss fire count and that pointed to cylinder 1.
Did the basics of swapping coils, spark plugs and injectors with another cylinder, but the miss fire stayed on cylinder 1.
Performed a compression test on all cylinders and obtained the following results.
Cylinder 1 - 50psi
Cylinder 2 - 150 psi
Cylinder 3 - 150 psi
Cylinder 4 - 150 psi
From that cylinder 1 had some sealing issues. First thought it would be carbon build up on the intake valves so did a walnut blast carbon clean and also ultrasonically cleaned the injectors.
This took the best part of day and didn't cure the problem.
I did a leak down test next and this shown that leak was pointing to the piston rings.
I dropped the car off at Awesome as taking the engine apart is above my mechanic skill level.
Awesome came back to me with the results of their diagnostics.
This picture shows piston 1 landing broken but the piece contained within the rings, this stopped any damage to the chamber and valves, extremely lucky.
I was going to get it rebuilt cheap as possible with OEM parts but after having a think I decided to take a different route.
The amount of tracks and fast road trips I do it would be pointless to rebuild it with stock parts.
I asked Awesome to make my engine bullet proof, so the following was installed:
Wossner Forged Pistons
PEC Steel H Beam Rods
APR 2000 Series Bolt Kit
Supertech Dual Spring Valvesprings
Uprated Big End Bearing Set
Uprated Breather Kit
Timing Belt Kit and Water Pump
Cam Follower
NGK BKR8EIX Spark Plugs
Nanodrive Motorsport 5w40 Oil
Head gaskets and other gaskets, aswell as coolant, other stuff.
Head was sent to the machine shop to be cleaned, skimmed, fit valve stems, Supertech valve springs, grind cam followers to suit uprated springs and rebuilt ready for installation.
Engine was bedded in with two lots of mineral oil. I've only just got the car back and need to do another 500 miles normal driving before I can give it some abuse again.
Now the engine is bullet proof it has now pointed me down the next path of upgrades, TTE480 and RS3 injectors! When will it stop?