I've noticed what seems like an occasional misfire on my 2013 Corsa 1.4 SE Automatic. A few months ago, I'd notice an occasional slight knock/bang and the revs would momentarily fall slightly and then go back to normal. Now the weather is a lot hotter, I've noticed when pulling away when the engine is hot the engine bangs quite a bit with the same slight drop in revs. Whilst waiting at a roundabout today for a few seconds there was a banging sensation that I felt throughout the car. Once on the move though, the car drives perfectly with plenty of smooth power. This banging/knocking only occurs when idling and just recently when pulling away.

I've read about quite a few problems with this 1.4 Ecotec engine - I'll get it looked at by a mechanic but I just wondered what is the most likely cause?

It will be a tricky noise to show the mechanic as it's not as though it does it all the time.

The car was recently serviced with 5 W 30 oil (as used from new) - I'm sure I read somewhere that using thicker oil could help but is this likely to be of help in my case?

Many thanks in advance