What is this small air hose on the cylinder cover for? There is a round
1/2" hole in the cover with a rubber ring. A nylon fork in the hole branches in two directions. I sensed a whiff of petrol in the car and found that the nylon thingy had popped out of the hole. I put it back, but it didn't fit well as the rubber ring had become brittle; it needed replacement.Today, I then replaced the rubber ring £2.90 . OK I suppose they have to store all and sundry bits for years and keep stock control. However, after I had replaced the rubber ring and everything was air tight, I started up and got check engine for a short while, then the idle raced up and down and eventually settled at the correct 900 rpm; after that no problems. It felt like the engine adjusted itself to the new conditions - can it really do that?