I own a 2004 rx8. No mods as of yet and it seems like I am in the shop more often than not. Never had a problem with the initial start but the idle seems to be getting worse. After it gets to temp the shake stops and about 20 minutes after driving the car shakes again. After 30 minutes the problems start. Come to a stop the rpm drops to 500 in second gear and shuts off without any noise or shaking. Takes a minute or so to start back up. Have to start down shifting and keeping the rpm high to keep the car on. Then it's like that for the rest of the day. No lights on the dash and 2 places could not pull any codes. Dealership charged me 225.00 for a compression test and said there is nothing we can do. Super mad!!!! Does anyone else have any Clue what is going on?

 

cat? coils? always first place to check

 

check your ess

 

Most likely it is a bad coil.

However, check your battery connections and charging system, including the battery.

 

Yep sounds like a misfire once the coils heat up.. Start with the coils but now you may need to replace spark plugs too. Or at least run some high octane racing fuel through it once you replace the failed coil/s..

 

Okay first off. How many miles on the engine and what were the results of the compression test done by the dealer? And what maintenance items have been replaced that you know of?

It sounds like another case of someone not doing their homework before buying an 8 year old rotary.

 

Engine has 81894 miles. The compression test, both rotors are passing, one is 8kpa over min advantage and the other is 37kpa over. I have a good cat with no blockage and in 10 drive cycles I only had 3 misfires. Oil, battery, tranny and did fluids are all good. The ess was dirty do they cleaned it. Throttle body has zero build up. All the maint is always up to date, I do a carb cleaning every oil change or every 2 1/2 months. I did my homework 4 years ago when I bought the car:-)

 

Oh. And all the tsb and recalls have been preformed or not needed. Coils and o2 sensors were replaced almost 2 years ago.

 

What do you think the high octane gas is going to do?

quart of water would do a lot more

 

Every 4 months or so I add Lucas fuel additive and take it on a red line drive. I do however try and get the rpms up to 8 once a day. Still no luck. No body knows what's going on but I'm getting used to driving with this problem.:-(

 

I would've bet on the ESS or throttle body not being clean, but you said you've eliminated these.
Where you located....................generally speaking.

 

Jacksonville Florida

 

Well.........you aren't but about 2 1/2 hours North, but there are a few members in that area that know what they are doing, hopefully one will jump in and possibly assist.
You might want to add JAX to your profile.