So, I changed out my spark plugs, plug wires, and ignition coils last week because my car idled rough. Prior to changing those items out, I didn't have any power loss problem. Now, my car is throwing a P0302. I can't seem to redline in 1st, 2nd, or 3rd gear. The tach needle just hovers around 6.5K rpm in 1st, 5.5K rpm in 2nd, and 4K rpm in third when I try to redline it. The car also seems to shake and stutter. It makes a lot of loud, "stuffy" noises, but it's not going fast like it's supposed to. I tried to redline it in neutral as well, but it only got up to around 6-6.5K rpm. The CEL was flashing but it didn't remain on. I dumped in a can of BG44K and ran the whole gas tank empty, but it didn't help.

My car is at 35,4XX miles now. It's an '04 GT. Used to run on 89 octane gas last year, but I never had any misfire or power loss problem. I'm now running 91 or 93 octane gas, though.

Could my cat converter be on its way out? This just seems so odd. I expected the car to run like how it used to before, not worse, after having changed out the plugs, wires, and coils.

I've read some of the old thread on similar problems like mine, but I still can't decide what kind of problem I may be having.

Help, please!!

 

^............Rear rotor misfire

Plugs in the right place? Meaning the right type in the right positions?
Plug wires nice and tight on both ends? You should hear them clilck on. New plug wires can sometimes be just a tad tricky.
Coil wiring okay? Take a close look at the connectors leading to the coils, those look okay? Any broken wires or pins sticking out of the connectors?

I don't see it being the CAT right now.

 

I'm pretty sure everything was installed correctly. If I remember correctly, the Trailing plugs are right above the respective Front and Rear Leading plugs. The RB Ultra wires I got were also installed correctly, as the wires for the Trailing plugs are shorter than the ones for the Leading plugs. All the connections on the ignition coils were nice and tight as well. The only thing I wasn't too sure about was the tightness of the plugs. I don't have a torque wrench/ratchet (in-lb), so I just turned it snug and then another 1/4 turn.

I think I may check everything again just to make sure. I just hope it isn't something else more serious and that it's starting to rear its ugly head now.

 

So, the CEL came on today and stayed on. I stopped by Autozone on my way home from work to get the codes. They were P0300, P0302 and P0410.

I'm still thinking that my cat's dead. I plan on bringing my car in to the dealership tomorrow.

 

^...................have them do a compression test while you are there.

 

Yup, my cat's officially dead. They placed an order for the cat, which should be here sometime next week. They also said that some "swirl valve" inside the air intake manifold got stuck, and thus, will need a complete decarbon. The cat and gasket cost $1443.00 and $11.72 respectively, and will be covered under the emission warranty. The decarbon costs $200.

I already ran through a can of BG44K on my last tank. Is it safe to assume that the "swirl valve" will unfreeze itself at some point? Or will I need to take my AEM intake off and somehow get inside the manifold to clean it? I don't even know what this "swirl valve" looks like or where it's located...If I could do it myself and save $200, I'd rather do that.

I'm gonna do a little search on old threads. But if anyone could help me out and save me some time, I'd greatly appreciate it.

 

Flashwing...What do you mean by rich and lean ?..and are you saying that as long as the electrode is intact then the spark plugs don't need to be changed ? I took a look at mines today and they look alot like these

 

Wow those look worse than mine

 

Got the cat converter replaced today. My car's idling, driving, and revving like a dream again! I love this car when it drives perfectly. I love it not when it acts up. But what can I do...except enjoy driving it.

 

Great!! That bad coil most likely took out the cat. How did you come out in the end?

 

^............Thinking that also.
This is just my opinion, but the more I hear of this car(meaning RX8's) with either a coil, plug, or plug wire problem......or maybe one with flooding issues(shutting off cold) that isn't taken care of pronto.......it seems to eat the kitty up pretty quick.

Glad yours appears to be running good now!



I will still stand by the fact that I don't think people should be going anywhere near 30k on a set of plugs. Again......my opinion.

 

Old Rotor, the cat converter was replaced under warranty, so it didn't cost me anything (thank God). If it was out of warranty, I'd be looking at almost $1,500 just for parts (cat & gasket). They also did the zoom power thing (decarbon the engine or something like that) and injection service. That cost a total of $250.

Mazurfer, I wasn't aware that spark plugs don't last long on rotary engines. Same thing with the ignition coils. I'd assume that those things last up to 100K miles. But now that I know it, I'd be more prepared to swap those out probably every 25K miles. As for the cat, if it goes again, I'll probably get that RP supercat instead of the OEM one (if the car's out of warranty by then).