I've just started to notice a slight smell of rotten eggs/sulfur inside the car, ususally when I'm starting, parking up or stationary. I have a 1999 1.8T which has done 110,000 miles.
I've done a search. My first reaction was the cat may be going bad , but performance wise it seems lively as ever. Its also been smog checked recently as part of an annual inspection and passed.
However, I'm wondering whether the spark plugs were gapped properly at the last service just after inspection by my local garage (who I have now disowned due to other issues!). To be honest, I'm frightened to check spark plugs, as they are well recessed, and I'm not sure whether my socket will fit. I don't even know what the correct spark plug gap should be, and even whether badly gap plugs would lead to unburned fuel . I seem to be averaging 27 MPG (US) at the moment through 50/50 city highway conditions
I'm also wondering whether the smell is coming from bacteria in the AC system. I must admit, the cabin filter looks as if its been in the car since new. Perhaps this is why the AC never gets really cold, and I have used it almost every time i've been out somewhere.
I've also heard that this small could be caused by a leaking vacuum hose, but then I wouldn't know where to look.
If anyone could guide me in the right direction and offer advice, I would be really greatful. Thanks!