i have a 95wrx wagon and recently changed the turbo to a td05 and ecu to a z4 since then i have had intermittent boost problems, the place that fitted them think the coil packs are most likely and after searching through posts on here i have to agree, just wondering is there another way of checking them other than just looking at them?
thanks
neill.

 

no the only real way to check them is take them out remove the rubber boot and look for any hairline cracks, sometimes not as obvious as others, you can measure the resistance as per the workshop manual a coil pack resistance can be in range but still play up.

 

Wen i pulled mine out to replace them there were no visible signs on them at all , but replacing them made the world of difference

 

Yep. Even though you can't see necessarily see any hairline cracks, they can exhibit microscopic ones that can still cause arcing. This happened with a couple of mine, too...

 

all was fine till i upped the power now under full boost in 4th and 5th i get the judder and misfire, i take it all 4 should be canged as they are 15 years old?

 

Yep. Exactly what happened to me. Upped boost to 1.1bar and it would miss.

You can get a specialist to look at them and, who knows, you may only have to replace one or two. But that said, the others won't be far behind in their ineffectiveness at that age. If you have the funds, best to replace all 4 at the same time. At least then you'll know that's that issue squared away for a further 10-15 years........