....spark plugs aren't meant to look like this are they?

So having established this fact, next question, what sort of permanent damage is likely to have been caused? The car was misfiring under load which led me to investigate these here plugs having already recently fitted new coil packs (the plugs were in one piece at that time).

I'm certain I need a new catalyst, but where would have all the bits of spark plug electrode and ceramic have ended up, given that there is a turbo between the combustion chambers and the cat? I want to read some real doom and gloom stories please.....

As for replacements, what's recommended? Original spec? Some premium brand off the shelf at Halfords? Or something a little more exotic? And finally (this thread is really I guess "ask a techie" but I think it will give causal observers a good laugh ), what torque should I be tightening the new plugs up too?

I have a feeling that the down fall of these plugs is centred around not spannering them up tightly enough after removing them to find out which of my coil packs had failed, and then ragging the engine around Silverstone for 20 mins at the start of the month down at tracks. I later found that three of the four plugs had substantially undo themselves in the cylinder block.

On the positive side, I'm really quite suprised the car has been running fine so long as you didn't use to much accelerator and waited until the engine was properly warm. Mind you the car is not running on the factory fitted ECU which I'm sure would have killed the engine and left me stranded at the side of the road.

Lee

An old haynes manual I have has pics of plugs.. .. Electrodes burned away = pre-ignition. On modern cars, i'm not sure what would cause this (i'm no expert either) apart from poor fuel or a knackered sensor somewhere causing bad ignition timing. VagCom might help.

As for torqueing plugs, they have a crushable washer on them, so when they are new, screw em in by hand plus about 1/4 turn. If re-using plugs the washer will already be crushed so hand tight plus just a bit to 'nip em up'.

Are they the correct plugs for the engine in standard spec, ie NGK PFR6Q and gapped to 0.7mm?

It's been a long time since I had a petrol car but i've tried plugs with Dual and quad electrodes with varying effects on performance. The quad ones were not great for the money but the dual ones were better. I would agree about the pre-ignition thing but i'm not sure loose plugs would cause this. You would more likely be noticing a drop in power due to reduced compression rather than misfiring but i'm no expert.