Mathieu Labbé

Hi guys, not sure if this should be in the engine subforum but I couldnt think of anywhere more fitting.

My 2012 A3 8P recently started to smell really bad on cold startup (around -10 Celsius). It stinks raw fuel for around 10-30 seconds around the car, and some black smoke is coming from the exhaust, but then it changes to normal white smoke. I know the engine runs rich when cold starts but I was told no exhaust black smoke should ever be considered normal.

I went to a thrusted VW/Audi independent shop and they told me the catalytic converter is going bad, since when warmed up, the first cat has higher temp on the entry than the exit. I thought that made perfect sense since I had very bad misfires going in cyl.2 on for a couple of weeks before the source was finally found and fixed (carbon build up). I imagine that could have clogged up the cat, with all that unburnt fuel.

Now, since I bought the car (5 months ago), I also smell something like very hot metal around the engine bay when the engine is hot. I was wondering if that could also be coming from the cat… I first noticed it when it was around 10-20 Celsius outside ant at the time I wasn’t smelling raw fuel at start up, or seeing any black smoke from the exhaust.

Basically, I’m trying to find out if a bad cat can be the cause of all of these symptoms:

• Raw fuel smell at very cold start (-10 celcius)
• Black smoke from exhaust at very cold start (for a few seconds max)
• Hot metal smell around engine bay when car is warmed up
• Lots of white smoke coming from the exhaust when driving (more than any other car I see)

Thanks and sorry for the wall of text!