i have recently brought an R reg corsa sport 1.4i 16v and have the same trouble misfiring at idle have changed sparks,leads had new lamber sensor ... was adviced by a mobile tune up guy it was a sticky lifter so used engine flush and changed oil still there ........ was adviced due to it drinkin fuel while idling it may be a jacked valve but surely power would be low in 3rd 4th and 5th( which isnt the case.... !) oh and rev counter is searching up down little movements while idling any help much appreiciated.:thumbs:

what I don't understand then is why was the car 100% fine, then handed it to them for a gearbox fitting, then now it's doing this, if it was related to plug gaps or something?

surely it's a elecrtical fault / sensor been moved / disconected or earth been moved / disconected when the gearbox was out.

plug gaps?

misfire at idle wont cause any real harm.

its prob just plugs or lead related

If its major overfueling causing the misfire you can get bore wash which takes the lubricating properties of oil away from your cylinder bores and they might wear quick, this takes place over a long period of time though

Depends whats causing it and if it's pinking or misfiring...

How much damage can a mis fire do to your car?

Since I got my car back from garage, it's started mis firing badly, and it sounds like a scooby... like it's only firing on 2 or 3 cylinders or something.

I'm not driving it ,but when we need to start it to test it, I'm worried I'm doing damage. What's the worse a mis fire could do? I have no cat so no worries about melting that.

I won't put a hole in my piston or anything from incorrect fueling will I?