Hello all I've recently just bought a 172 cup had it for a few days and have noticed a faint knock sound when on tick over also the car idles under around 8000rpm and car shakes from time to time while sat on tick over... Anyone have any ideas on what it could be or if it's normal etc? As I'm not very car minded and haven't got a clue about engine diagnosis and so on so take pitty on me and try to explains as simply as possible for a not so car minded clio owner any help would be much appreciated