Your opinion please
 

My 05 has slightly over 100K miles. It starts fine and runs like a champ when cold. But after it gets hot it refuses to idle. Then when it dies, it won't start while hot. It's kinda tricky trying to keep the motor running while also working the clutch and brake.

I realize these are signs that the engine probably needs a rebuild or replacement.

The local dealer wants 240.00 to diagnose the car. I am reluctant to pay the money as I'm 98% sure it needs a new engine. However I am not an experienced RX8 mechanic.

Is there a chance that my problem is something other than low compression/worn out engine? Would you pay the $240.00 to know for sure what's going on?

Thanks!

Definitely sounds like compression. 240 is steep, can you find another dealer? The procedure duration is supposed to be in the shop manual and it's about 1 hour, ao you should be getting charged... 1hour labour. Seriously it's not even an hour of work. If the dealer is overcharging, report them to Mazda North America.

It's tricky, and a bit dangerous, to drive the car more than 20 minutes, which is why I called the closest dealer. The next closest dealer is quite a bit farther, and I'd prefer not to drive that far. I could have it towed, but of course that's another expense.

My opinion is that we see this type of thread many times a month. We provide insight, we offer recommendations and we assist with troubleshooting.
Have you by chance read any of those threads? Have you done any troubleshooting? Have you provided us any maintenance history?

I know that you're struggling, but please do some reading so that you can better understand your issue, so that we in turn can better assist you.

Thanks for your feedback. I've read quite a bit, which is how I reached the conclusion that the problem is most likely low compression. Given the symptoms I described, I can reach no other conclusion. In my reading I have found no problem, other than low compression, that would cause my car to behave the way it is. But I'm not perfect, so that's why I'm asking other, more experienced owners if there is any other problem that could cause no idle/no start when hot.

I realize there's a very small chance....or maybe none....that the fix is anything other than a new engine. But I figured there's no harm in asking before I spend 5 grand on a new engine, or sell the car.

For what it's worth, I'm the 2nd owner, I bought it 3 and 1/2 years ago with about 65000 miles on it. I redline it every drive (after warm) and change the oil every 3 to 4000 miles. I don't know how the previous owner treated the car.

Have you verified plugs/coils?
Condition/pressure of your fuel filter/pump?
Inspect cat for clogging / damage?
Air filter/MAF sensor?

Chances are it is compression, but with everything else working, you should be able to get the car to the dealer to have it inspected.

Just wanted to follow up on OP to see if he figured it out. I had this happen to me a few months back, I have a 04 with 134K miles on it. My battery around the same time I had the poor idle when hot issue and after replace battery, replaced coils, plugs and wires and now back to normal. Hopefully OP was able to try out a few relatively inexpensive fixes first

Sounds like compression to me.

Thread from a year ago. Wonder how it all turned out .

OK, here's an update. Due to the symptoms I was fairly sure the engine had lost compression and would need rebuilding. The cost of towing, compression testing, and the engine rebuild exceeded the value of the car. I sold the car, as-is, for cheap. It was a fun car, and I knew the risks when I bought it. Now I drive a Mini Cooper S. Not quite the same, but still fun.