Poor Running - Missfires on start-up, may clear after a short time - NB (MKII)

Coil pack failure is common & gives the above symptoms.

There is no conclusive test that can be carried out on the coil pack to establish if they are the cause. First try & establish that while the fault is occuring that there is no spark at 2 of the spark plugs, either 1 & 4 or 2 & 3. The the best test to confirm coil pack failure is, when the engine is displaying the symptoms, wiggle the low tension connectors on each coil pack one at a time and observe if the condition improves.

The engine will have lost saprk on 2 out of 4 cylinders in this failed condition. Fuel will still be being injected into all cylinders so unburnt fuel will be forced out through the exhaust, this causes rapid failure of the catalytic converter.