Check out the Exhaust manifold. I am having major probs with my 1.6 s reg Scenic. I noticed the same smell and looked under the bonnet. I removed the heat shield and spotted a large crack in the exhaust manifold!!. this apparantly is a common fault with renaults. I have now swapped it. the smell has stopped but the car still runs badly. I have also swapped the
and sparkplugs. Checking the timing is my next mission.