When to replace rotor/cap?
 

How often do the rotors and caps need to be replaced on a 964?

I'm actually not sure how many miles on these. Do they look worn? The black marks can be scratched off fairly easily, but obviously aren't pretty...

How about spark plug wires? Do spark plug wires even wear out?

Thanks,
Steve

http://dio159.diomedestorage.com/dl/...9/P1030036.JPG

http://dio314.diomedestorage.com/dl/...0/P1030039.JPG

Zoomed in...

http://dio265.diomedestorage.com/dl/...903x848%29.jpg

some do it every major tune

for the wires, you can spray a water mist near them with the motor running at night - if you see anything interesting then either replace the wires or wait for the drugs to wear off

wish I had a better answer...

That cap looks to have significant wear. If I had to guess, I would say every 15K miles would be a good time. You could go longer, but that is such a cheap replaceable, why not. If it does wear out, you will be stranded. I guess I would replace them every time you do the spark plugs. I could not start my car for a couple weeks, once, and I checked the cap and rotor. They looked in decent shape. Several weeks later, still no start, I replaced them, and all was good.

Thanks for the tips - new caps, rotors, spark plugs on the way ($255)...

-Steve