I'm not sure how it got there, but it happened a couple of days ago. something punctured a hole in the exhaust pipe right below the engine on my '89 Civic 1.5. Every since then i hear a slight popping sound occasionally and now my car idles up around 1000rpms sometimes a bit higher from the 7-800 rpms it use to idle at. Would the hole in the exhaust right there cause that? Any info would be greatly appreciated. Thanks.