Suddenly my '05 S60 2.5T w/66,000 miles has developed a miss, or at least it drives as though it is missing on a cylinder. No check engine light or message. Waiting for VTC scanner to arrive from UPS. Can I test coil packs/wires/plus by disconnecting one pack at a time with engine running, or might that cause damage to electronics? Any other ideas? I fear my scanner won't detect anything when it gets here, but keeping my fingers crossed. This is my first Volvo, and I can't stand thought of taking her to the dealer, so any feedback would be welocome. Thanks

 

you can test plugs without them in the cylinders , they will spark. but u can get testing lights that go inbetween the plug and the wires/coil paks.

 

I've had the same thing happen to my XC70, I'm suspicious of the coil pack as well. I posted a thread last night but no replies yet, I have the same concerns as you about damaging the system by disconnecting wires. Mine however is showing the check engine light. I guess it's time to invest in a scanner. I'll keep you posted if anyone replies to my thread.