To anyone that can help out;
I have a 96 Civic H/B with a 99 LS swap in it. Here's the situation - when cold, she sounds fine. After warming up, she sounds like a diesel, but only from inside the car. Once outside the vehicle and the hood open, the engine sounds fine. I have looked for loose stuff all over the place, but nothing has come up. I even looked for exhaust leaks, no luck. I was thinking that maybe all I need is a little valve lash adjustment. What do you guys think? All info will be appreciated. Thanks!
P.S. Could it be a clogged cat??

 

sounds like the cat is clogged. What happens if you give it some gas and let off real fast? Does it rattle or make any abnormal sounds. It sounds like your cat is bad. take it off and check it out!

-Mike

 

AMS MIKE;
Glad someone actually replied to my post. Thanks! It wouldn't surprise me if the cat is clogged. Since I didn't have one when I got done with the swap, a friend of mine gave me his old one for fitting purposes. I wanted to be able to remove it at will instead of welding it in place. His cat came off a 99 Civic EX turbocharged. That was his stock cat. It probably ran out of lives . If I give it some gas and let off quickly, it sounds like a SRT-4 between shifts. No, it does not rattle. Not trying to be a smart ***, but if I take it off and run it, I won't be able to hear a darn thing wrong with it. I was thinking about buying a new one: CATCO. I'm also going to try and see how my valve lash is doing since I'm going to be working on her. Maybe once I replace my valve springs and retainers with type R ones she'll do better. Just kidding. Thanks for the help!

 

Not sure about your emmision laws where you are. But you have an OBD2 car and if you want to keep it legal. get a CATCO oem cat like you said. If you don't care, get a Car Sound (Magnaflow) high-glow cat...they are cheaper but not OBDII compliant.

If you want to be straight piped (not legal) you can punch out the car (hollow it) or you can run a test pipe where the cat used to be.

And I understand about taking off the cat and driving open downpipe to see if that was it because you can't hear ****. Ask DXTRIX....he won't go in my H22 N/A hatch because I always have it open downpipe. Ears ring like a ****.

Good luck on your car

 

AMS MIKE;
Unlike Cali, we don't do ECU/emissions testing over here, so pretty much everything goes. Just don't go to the ref with too much stuff disconnected, smoking all over the place, or with the CEL on. I'm going to lean towards staying "legal" anyhow, so I'll go with the CATCO. I might give the test pipe a shot since a friend of mine has one. Yes, open downpipe do get pretty loud. Thanks for the help!