Thanks.
On a ramp it turned out just to be worn heat-shield.

 

Good news.
Thanks for the update.

 

Just an update.
Replaced plugs...one of them had the connector broken...it was held in by the leads:
The slight rough idle has now gone...but I still feel a 'surge' around 7krpm.

 

Did you get any CELs?
If the plug wasn't firing, it could have been dumping excess fuel in the cat.

 

Must be VTEC kicking in.

 

Nope, no CELs. There is a slight hesitation around 4krpm too. I'm going for a long drive tomorrow so will double check the smoothness of acceleration. You reckon the CAT could be dying?

 

Well, usually if a plug (or coil) isn't firing, the fuel isn't burning in the chamber, but dumped into the exhaust where it's reignited and can damage the cat.
If you can drop the cat and inspect it, it might be a good idea.

 

Definitely inspect your catalyst. Dumping fuel and oil into it is a recipe for disaster, and if it starts to clog, it can start cooking your rear rotor.

 

Thanks for the help BigCajun and Steve.
After the long drive, the car feels better now - now more surges and power is there throughout the rev range.
Could it still be the CAT?

I was feeling underneath my seat (right-hand drive), the carpet all feels quite warm, and touched this very hot screw/nut - is it normal for it to be hot? Or a bad sign?
Here's a picture of it - slight gold shimmer underneath the plastic:

<img src="https://lsabrw.bn1301.livefilestore.com/y3mhhZWbqkamv0qHqbXyzik9Rj-OWLNnwg1GgUArHbo4ygUOQ-JVymSCIUpXNJenJ_cwfQRaEse2JJppPLLFh598RjIu7tSgyCyX DV8fj2Wtk5LJb_XZXwf3NZtQfkzl3RBjJUM0vctUFrSXFffnej 9LTTS7jncZDIdiCL7GYKUXGY?width=660&height=372&crop mode=none" width="660" height="372" />

 

When inspecting the cat, what should I be looking for? Just having a clear honeycomb, intact, not melty and unhappy, or what? If it's cracked or something, is it bad?

Never done cat work, going to take a look soon.

Does anyone have pics of good and bad, for comparison?

 

Testing a cat should be done the proper way, a visual is not really the proper way.

 

Awesome, thanks 9K!

 

Hey so this works on the rx8? Can I use ultra gauge or do I need that specific reader? I can probably rent it from autozone.

 

this thread is also bad in many ways

if you suspect a clogged/broken cat element then a visual inspection is correct

if you have this cat code then you do this other method, but based on your other thread you don’t have this code.

again, 1 + 1 = 2

3 is an incorrect answer

.

 

I still plan on visually inspecting the catalytic converter and replacing the rear 02 sensor, but for future sake if I am able to also inspect the catalytic converter by infrared scanner + bi-directional scan tool, more data is greater than less right? Worst case I just waste my time learning something new.

Edit: I also am very interested in swapping oem cat for BHR midpipe. So im on the fence about replacing the 02 sensor if im going to swap. Correct me if I'm wrong but the rear 02 sensor serves no purpose with midpipe.

 

if your vehicle needs to pass an emission test then it serves a purpose. If not, then you’re right, it serves no useful purpose.

that’s not a low end scan tool, but if that’s what you want to do then by all means do so

.

 

Correct, no emissions test required in my state. As always thanks for the advice.

 

I just wanted to add my cat experience to the thread. My car was stumbling after 5k rpm with no codes. I changed the plugs and coils which helped but still not right. I decided to order a new aftermarket cat. When I removed the cat pieces fell out it was a mess. Installed new cat and the car screams all the way to redline.

moral of the story these cars cool cats. In my case it was likely old coils and plugs dumping fuel into the car. This was previous owner stuff.

engine has 90k on it.

 

Careful with aftermarket cats..they don't withstand as much heat as OEM and fail much much quicker