loud exhaust problem

[flight]

Hey guys,

The Melbourne guys know of my problems with the EPA. Thread
HERE

Long story short, car got tested with OEM muffler and still failed by 3-4 db. I have the Taitec headers still on there which I am sure is the cause, but considering the state of my OEM manifolds, I cannot replace them for a while. (see the thread for info).

one of the 02 sensors was not installed on the car - would that cause the car to run rich and hence a 'little' louder. My guess is it would no be not enough to effect the reading, but what do you guys think?

Also, and here is the main thing, it was suggested to me to create a steel plate with holes in it, and place it as a gasket between the cats and the exhaust. This would increase back pressure and quieten the exhaust. Question is, are there any serious side affects? I would remove the fake gasket after the test. I do not think I would be creating any more back pressure than there was when the OEM manifolds were on the car.

The test is done at 5475 rpm and the engine is held there for about 15 secs.

HELP! I can't drive my car until this is fixed

 

[AU_NSX]

Long story short, car got tested with OEM muffler and still failed by 3-4 db.

WHAT??? I can't believe that

I have the Taitec headers still on there which I am sure is the cause,.

I would be surprised if they are the cause...
Have you checked your CATS to make sure they are intact inside?
What about your standard exhaust. Are the internals and baffling still okay?
Are they testing your car to the db standard that was in effect at the time your car was made or current standards which are stricter?

one of the 02 sensors was not installed on the car - would that cause the car to run rich and hence a 'little' louder. My guess is it would no be not enough to effect the reading, but what do you guys think?

No effect.

Also, and here is the main thing, it was suggested to me to create a steel plate with holes in it, and place it as a gasket between the cats and the exhaust. This would increase back pressure and quieten the exhaust. Question is, are there any serious side affects? I would remove the fake gasket after the test. I do not think I would be creating any more back pressure than there was when the OEM manifolds were on the car.

Yes, this will work. Increasing the backpressure can be done as long as you don't run at too high RPM for too long.... i.e. Don't do a track day, but for driving to and from the testing centre and doing the test to 5500 for 15secs will not harm your motor.

Good luck with it mate. Let me know how you go.

Mike

 

[flight]

WHAT??? I can't believe that

Tell me about it. I was confident that this would fix the problem.

Pre '83 allowed 96 db, post 83' allowed 90db. I think I am allowed 92db because rear engined. With the OEM muffler, my reading was 95db at 5475rpm!!!!!!!! I was shocked.

How can I check if the original muffler is baffling correctly? Granted it is an 8 year old muffler and may not be working as when new, anything I can do to the OEM muffle temporarily to pass the test? I only have Catrell intake and headers non-standard on the car.

My last resort is the fake gasket spagetti strainer thing...

Oh, and the dealer just rang me (getting the 02 sensor problem fixed) and my car still has the check engine light on. They dunno why - the are thinking it is because the new position. I told them no one on here had that problem. They are running diagnostics right now. Not a good week so far.

 

[dippy9]

Sorry to hear of your troubles. Hope all goes well. remember to keep me informed as well just in case it happens to me (knock on wood)

 

[flight]

Will do dippy.

I hope it does not happen to you - it is a royal pain in the butt. You know how the police are here. I want to move Don't know if it is any better in Qld, but at least the weather is good.

BTW, dealer got back to me - 02 sensors stuffed (who's fault ). Need to replace them. Told me $550.00 per sensor....know how I can get them cheaper? Maybe some of those contacts you were talking about :wink:

 

[dippy9]

There is a place called Hondwreck on Westall road in Clayton that has a nsx wrecking i'm pretty sure they have them but if you want i can chase it up for you.