Pap-pap Noise

[dreavis]

Hi. I apologize for this post because I know I read something about this a couple years ago, but can't find it now.

Anyway, my 77 makes a pap-pap noise in between shifts - particularly when the cars is not up to temp. I remember my Fiat guy telling me that it isn't harmful to the car and that it was a trap or canister of some kind (my memory is a little hazy today.)
If anyone knows what I'm talking about and has more information I'd appreciate it. What I am specifically interest to know is. What is it? How easy and costly is it to fix? Is it necessary to fix it or is the car fine as is?

As I said, once the car is warmit seems to do it much less if at all. Also, and I'm not sure if this is helpful in answering my questions, but the car has a new muffler and cat as of about 1000 miles ago.

[azruss]

not sure what you mean. it this an engine noise? exhaust noise? Is the sound random or rhythmic? need more info.

[dreavis]

The sound occurs between shifts and sounds like it is coming from the exhaust system. It typically occurs when I first start driving and seems to mostly go away when the car is up to temp. When I change gears and the clutch hits the floor, there is a pap-pap-pap noise. I have assumed it has something to do with exhaust gasses. As I mentioned, my mechanic gave the part that should eliminate the noise a name that I can't remember and noted that it didn't need to be replaced because it wouldn't cause any harm as it is.

I am interested because if it is something simple and inexpensive (or if could damage the car), I'd want to fix it

Thanks!

[RRoller123]

My X1/9 did this exact same thing, and it turned out to be the exhaust system rattling against/slightly touching the frame between shifts, due to the engine moving slightly on its mounts as the engine de-torqued between shifts.