Can coil packs fail gradually?? What else could it be.

[andyiseddy02]

I have a Passat with the BWA engine, we have had it over four years and it has been excellent I really like it.

Two things happened last week that made me wonder if there is a problem about to appear. After a run of about forty minutes it was parked up for about an hour, when I came out to start it, it was turning over but not firing, I tried again and it started fine.
Next day after it was stood overnight it started fine but was mis-firing, felt like it was running on three cylinders, it cleared after about 15 seconds and has been fine since.

Straight away I thought a coil pack was on it's way out. A Carista scan showed nothing. Do coil packs fail intermittently or do they just fail. Any ideas. The car is in fine health and servicing is fully up to date.

[KatieT]

When were the spark plugs last changed?

[andyiseddy02]

Last service about 5k miles ago.

I was ready to get four new coil packs and plugs then I thought I will see how it goes. We did a good run at the weekend and it was fine so I will just monitor the situation.
 

[andyiseddy02]

It has done the mis-fire a couple more times now, only when starting from cold. Expecting trouble soon.

[muff1991]

could well be a coil pack.. but just to rule something else out: do you have access to VCDS or similar to check the readings on the Coolant Temperature Sensor when cold before starting?