hi .I have a 2.0 ltr petrol which has a constant misfire but is showing no faults on diagnotic.Also the charcoal filter seems to be working overtime.
Any ideas where to look would be helpfull.
Have changed coil pack and plugs but no change.
I had a similar fault a while back on my 307, 2.0 xsi, turned out to be the o2 sensor. depending on your model you may have 2,one on the front of the cat and one just behind. you could try the front one, i heard a while back there were alot of "bad" sensors around.ihope this helps.