I have a 2004 RX8 that has recently been stalling on me. It idles rough as well. It'll stall and then I'll need to go through the engine deflooding procedure just to get it started again. After that hard start it seems to stall when I get to a stop. It's intermittent so it's weird. I have 99,888 miles on it and had the original engine replaced at 96,000. It's at the dealership again. I took it in to them 100 miles ago and was told it's carbon build up which should have been taken care of then. So I'm not too confident that's all it is. Is there something I should tell them to look at that they're missing?

Any ideas?

 

I'd be willing to bet your cat is bad. The ECU tends to compensate little by little for bad back pressure over time, then you disconnect the battery for a bit of work, the ECU "forgets" its drive cycle info, and BAM! bad idling and stalls at stop signs out of nowhere. Cat is under the 100,000 warranty.

 

Cat is actually outside of warranty (80k miles/8years).
Have you cleaned your air filter/MAF sensor/eccentric shaft sensor? Plugs/ coils?

If you can, pull down the front of the cat and have a look

 

Maybe that's whats wrong with mine too. I've been having the exact same problem, and mines 44k miles with a reman put in at 33k =/

 

Open Road Mazda informed me that it could be a broken exhaust manifold. They need to take the engine out to look at the exhaust manifold. Does that sound right? Does the engine has to come out?

Also I had the engine replaced by Mazda 1700 miles ago and I'm at 99,888 just under the 100,000 powertrain. I'm told the manifold won't be covered by warranty. Has anyone had one replaced and give me an estimate on their cost? I'm being told that it's 1100-1200 just of the manifold not including labor. I can get a Mazda OEM exhaust manifold online for 400. Will they install that?

I was also told that if the engine is bad it'll be replaced under warranty. If it was installed incorrectly it will be covered under warranty. But if the manifold is cracked I'm SOL.

I'm being charged 1000 dollars so they can take the engine out and take a good look. That's a big gamble on an 04 with nearly 100,000 miles. Although only 1700 on a rebuilt engine and clutch.

 

Sorry, I mispoke, it's the intake manifold.

Does anyone know where I can buy an OEM intake manifold?