Hesitation Under Load In All Gears and NOISE
 

Details:
2004 MT
85K Miles

I started getting a really bad hesitation a few months ago and a horrible sound coming from what I assumed to be the Cat.
I immediately changed the plugs, wires and Coils.
I also pulled the Cat to take a look but didn't notice anything unusual.

On my last long drive, I had a misfire CEL for the second rotor.

Now I have all these symptoms again, worse.

Right around 4K RPM, I hit a wall in power, I hear a horrible bogged, rough noise coming from directly under the center console area and the car slowly climbs in RPS. This is in all gears.

Please help me narrow this down.

Sounds like a clogged cat...you can't visibly inspect them so...have you tried working with a local to swap out your cat with one of their's or a midpipe to see if it takes care of it? Also have you got any stored CELs that just haven't kicked out yet? And can you define "horrible sound" a little better?

Agree it's a clogged cat. and you CAN visibly inspect it. Your cat. has a 80K mile emissions warranty. Bring it in to the dealer and describe the situation. It's a common problem. They should replace it for you under warranty.

Edit: Just saw your mileage. You may not be under warranty anymore. I would still bring it in and see if they would be willing to replace it for you anyway because you're so close. If not get an aftermarket replacement cat. rx7store.net has one for ~$350.

Bad Kitty!
You can talk to the dealership and see if they can do anything for you. Being over warranty and all. Just remind them that this did not happen overnight.
Don't let the dealer try to sell you a new one, BIG $$$ Try and find a used one local or go with an aftermarket midpipe.

Had the same problem
 

Sounds like the same problem we just had; idle was a bit off, engine started to break down on acceleration and the most god-awful racket. The dealer installed a new shutter valve and the car runs sweet again. They told us the the old valve was all carboned up and needed replacing. Hope this helps.

JT in VA

I've got the same thing going on. The CAT is brand new (<1000 miles). The car has been sitting for about 2 weeks and didn't have the problem the last time I drove it. I hit the same wall. The car runs fine at low throttle but anything more than 1/2 and it bogs down and I get a flashing CEL. There is a definite line between when it runs well and when it runs poorly and that line seems to change.

FWIW, mine turned out to be bad coils. The CEL was a misfire. After some more searching here I bought the coils from Rock Auto and installed them in under an hour. (And I actually really hate working on cars) Now the car runs better than it has in a while.