I have a 2005 Honda CRV LX. I replaced my catalytic converter with an aftermarket one I found on Amazon (https://goo.gl/GTBnjD). The check engine light came on for the converter and I took it to a shop that confirmed it needed to be replaced. I had also been smelling fumes for some time which was probably due to the corroded connection at the back of the catalytic converter. And it was a little noisy. It came with a flex gasket for the manifold, but it didn't fit. So I bought a better one from Autozone (https://goo.gl/cL4iAP). It seemed to fit well. The spring bolts came with the converter and installed without a problem. I also replaced the spark plugs (same NGK Laser Iridium that it had in it) and air filter while I was working on it.

When I started the car after I was done, it was much quieter while idling. Even while revving the engine in park, the exhaust sounded great. However, when I actually drove it, it was quite noisy while accelerating. Quiet while coasting. Only during accelerating did it make noise. I also don't notice any exhaust fumes.

I'm stumped as to what the problem is. It sounds like an exhaust leak, but there are no other indications of a leak and it's quiet as can be when the car is not in motion. Any thoughts?

 

You might just need to drive it because when I replaced the catalytic converter in mine for the first week or so if ran funny and mad some weird noises but it went away as soon as the computer system started reading the cat properly.

 

exactly what kind of noises are we talking about ?