993turbo

Lately my Boxster (99' 2,5) have been acting up occasionally during start from cold. It is only now and then. Not every time.

When starting from cold it starts rough. Like its running on 5 cyl. After a little while it throws the CEL. Misfire Cyl3 (P0303 Cylinder 3 misfire) or last time it happened Misfire Cyl2. (P0302 Cylinder 2 misfire). After the rough start, which lasts like 3 - 5 secs, it runs like champ.

Spark plugs are new. AOS new.

What are the likely faults? Coil packs?

Weazer

One or more cracked coils. My Boxster would do this, particularly when it was humid/raining. Checked coils to find 4 out of 6 had hairline cracks. Replaced the coils and, voila, problem solved.

993turbo

Sounds reasonable.

pilot4fn

As an easy to check item first - check that the leads to the coils are well secured in place under the rubber boots. If the lead is not well in place, you'll get misfires in that cylinder.

993turbo

All secured and well in place.