Smells of fumes and down on power

[Wollemi]

My 987.2 S has always smelt a bit hot oily from outside the car but very recently it is smelling of fumes (exhaust?) whilst driving and this is a lot more noticeable when driving with the roof down - as if fumes are being sucked into the car. It also feels down on power, not as sharp as it should do.
What sort of things should I be checking for?
(or getting someone to check for me - I am a mechanical incompetent )

 

[Motorhead]

Hi Graham,

In the first instance I'd make sure that you haven't got an exhaust manifold or exhaust system leak. This should be apparent if you stick your head under the rear of the car on both sides to see if you can hear it blowing, although any competent garage should be able to check it out for you.

Jeff

 

[tscaptain]

MAF possibly?

 

[mickybarb]

Similar problem. Found one of the lambda sensors faulty (pre cat). Seems to have sorted problem. Fumes gone and engine running sweeter.