[JGriff]

Besides failing the test due to smog concerns, does a faulty cap cause any kind of driveability problems? I've heard that it does/could on newer cars, but I don't know whether it could on a 12 year old Porsche.

I wonder, because my car has an intermittent problem (although it is happening more frequently recently) where it idles rough when I restart it after driving it (i.e. after it has warmed up).

I'm thinking that it could be the O2 sensor (which is on the way from Pelican as I type this), but I wonder if it has anything to do with the gas cap and the whole vapor recovery system on these cars. (I looked in the owner's manual, and there is a whole page that describes the system. Yikes!!)

When I take the cap off after driving it, to refuel, I do not get a hissing sound.

What say all? Should I try replacing the cap? If so, I'll probably do so after I replace the O2 sensor.

My gas cap is keyed for use with the OEM key. If I order a new cap, is there any way to swap the lock components, so that I don't need two keys?

Thanks.

Jim