possible engine damage from bad cat.
 

Bought 04 RX-8. 4 days later got a CEL for bad cat. Dealer wanted $1400. Was running good so I thought I would wait til I could pay. Several weeks ago started misfiring. Changed coils plugs & wires. Still the same. I want to put a midpipe on. Could engine be damaged?

Could be. Were you only getting a cel or did you have power loss as well? Did you have trouble revving past about 6k rpms at any point?

If the car felt like that then yes you probably did damage it. For all you know the cat has already been knocked out by the previous owner, did you ever look at it?

It was running fine up to a few weeks ago. Sputtered when accelerating at higher RPM. Took it to an ind. shop, scanned bad cat & misfire code. They thought it needed a tuneup. Then it started doing it at lower RPM but only for hard acceleration. Did tuneup. Runs fine in "normal" driving. I haven't taken cat off yet. I thought it too quiet for a hollow cat. I want to put a BHR midpipe on it.

Well if you are having power issues with hard acceleration then that is not a good sign. The longer you wait the more possible damage you are doing to the engine. If you think the cat is bad then take it off and look inside it, if you see problems then knock it out yourself until you can buy the bhr pipe.

I'm not driving it now. I was hoping I had fixed it when I found bad plug & coil. When it still wasn't running right, I parked it. I was hoping (wishing) someone had same experience & fixed it by taking cat off. (Stoopid fatfinger) I was wondering if it was worth gambling $450 on a pipe & what the odds were of the engine being OK.

Try doing a google search on this site. Search for " site:rx8club.com cat misfire " in google without the quotes. Lots of people have had cat troubles so you will get many results.

Thanks for your input. I'll do that.

Please reference to the link in my signature - It's the 'unofficial' misfire thread. Should give you lots of the information you need on possible problems, and their corresponding solutions.

Thanks for sending me to your misfire thread. Very informative. I ordered BHR midpipe yesterday in the hope that I didn't do permanent damage to my engine. Mr. Hill even offered some advice on things I should try. I wish I would have found you guys sooner. Been a huge help. Keeping my fingers crossed. Belated Happy Birthday!

Update
 

THREAD RESSURECTION:

Here I am to update my first thread and update with an answer to my own question 4 years later.

Yeah, I think I did damage it.:(

First off, thanks to all of the veterans here who have helped me along the way.

She would have died a long time ago without your help.:)

Everything that I did afterwards was a result of what I leaned here, both from helpful members answering my ignorant questions, and researching the forum on my own.

Anyway, after my initial difficulties, I removed the cat to find the front half of the strata almost completely gone with only a goose egg sized chunk remaining.
At this time I had around 23k miles on it after buying it the previous July 31st with 18.5k.

I then replaced the original coils, wires, & plugs with Advance Auto parts components.
I found one bad coil with the corresponding plug almost completely carboned over, that was causing my misfire and ruined my cat.

I then bought a new BHR resonated midpipe and did all of the usual recommended maintenance, ESS, MAF sensor cleaning, and 20 brake stomp.
Also started premixing various JASO certified 2 stroke oils, before settling on Lucas semi-synthetic, and regular oil changes with Mobil1 0W40.
Ran great for the most part ever since.

Fast forward, after 2 more batteries, 2 fuel pumps, a BHR ignition kit and then just for the hell of it, a SakeBomb ignition kit, I finally got the letter a few months ago to replace my airbags, still running like a bat outta hell with about 65k on it.

Figured WTF, get my first compression test while I'm there expecting to pass with flying colors, only to be told it was failing with low 6s and high 5s.
:(

Only recently has it started taking an extra second or 2 for hot starts.

So to sum up, even though I have no way of knowing for certain, even though I maintained it for the most part as we all should, I'm thinking ignorantly driving it with a bad cat for the first few months caused my engine to fail 'prematurely', and facing the prospect of rebuilding it.

Still running good at +72k.
:)

Sounds like it's time to start planning a rebuild.

Maybe boost this time?

Travis

It's in the pipeline, I've been researching it, but life keeps getting in the way.
It's ironic that a week after I started this thread was when I found out I was sick, and right when I find out I would need a rebuild was when I thought I would need a transplant
"Isn't that nice?"

I started the rebuilders thread when I first became aware of the possibility;

https://www.rx8club.com/rx-8-discuss...ilders-265177/

(Btw, I think it's Sticky worthy.;))

WaitingforFI was nice enough to print out Rotary Ressurection's engine removal thread for me and even put it in a nice binder.
I owe him a solid for that one.

I need to get my truck in shape before I commit to the rebuild, I've been neglecting it since I got the 8.

There's been way too much bad stuff going on this year, hopefully things are settling down close to what passes for normal, and I can get around to taking care of unfinished business.

As far as boost goes, I'm happy with it as is, and I don't want the extra expense and effort to go through with it.

Well BC, get that truck running like it should so you can get that engine out, rebuilt and running like a champ again.

That's the plan amigo.
:)

At what RPM did they measure These compression numbers?
This saturday I will gut my kitty because it's apparently clogged. I will update this thread aswell to the next users using the search function can find more info.

250 rpm.

Yeah that's pretty weak.

Try to decarbonize the engine with seafoam or zoomzoom cleaner. Do the Treatment like 2 or 3 times with say 100 miles in between. There's nothing to lose and it's worth the try.

https://www.rx8club.com/series-i-tec...7/#post4408673

The admin gained 2 full bars with this method.

^ no seafoam is snake oil. I know riwwp personally and he uses distilled water(steam cleaning) I helped him do it to several 8's that's what actually cleaned out the carbon and loosed up the stuck seals

hmmmm i remember that day. quite a few were done at that meet lol

Yes but riwwps results were never proven to my knowledge.

He was compiling data but has yet to Share iirc.

So we don't know for sure just how well the steam cleaning works.

Travis

He used the psyentific method ...

I just wish we could have had hard data on this point.

Comp scores/fuel mileage prior to and after the test with a minimum of 10 cars for a controlled group study.

Travis

:rollingla


like I said in the previous post ...

he did scope a few engines before and after which i know isnt the same as cracking the keg open but its something. didnt you do before and after tests at my bros shop travis?

I'm not doubting you mentioned it, just didn't see it.

I still wish we had more data.

Travis

No, we were going to but he started steaming engines before I tested em.