My spark plugs! Pics inside

[dj0nes]

Hi all, I have been having some problems with my Cupra under boost so I am just going through the painful elimination process as Vagcom can't help me, I have just checked the plugs and for some reason one is different to the other three

That aside do the colour of them look okay?

Image link is here - imageshack.us/photo/my-images/706/img059tv.jpg/ (sorry, forum won't let me embed images yet due to post count.)

 

[Dan1720v]

Ignore the colour, as this only shows the colour of the last burn cycle. but theres no bits missing etc.

 

[nd-photo.nl]

They look quite alright to me? What are the problems to begin with?

 

[dj0nes]

Cheers guys.
Car is hesitating on boost, sometimes it goes fine other times it holds back and will backfire at around 3500/4000 rpm.

 

[wayne n]

I would say your odd plug has a different heat rating to the other three so you need to replace them with a matched set of 4.