Good Morning,

i am new to the rotary but not new to cars.

i have recently replaced the engine in my 2004 rx8. it starts right up in the morning with no issues and then when i go to lunch during work. but as i am pulling into a parking space it will idle low then die on me. i can keep the engine going as long as i two foot the car. any suggestions will be great!

( i was having a overheating issue due to a bad thermostat but that has been taken care of)

 

Starting and idling fine when cold but not when hot is a common symptom of low compression. There could be other causes but lets focus on this since you mentioned that you just replaced the engine.

Where did your engine come from? Was it a JDM engine off of eBay, a rebuilt motor, a remanufactured motor from Mazda, or something else?

How many miles are on this engine?

Did the overheating problem happen before or after replacing the engine? If it happened after, how hot did it get and how long did you drive it while overheating?

 

So after the engine was replace it sat for ab six months other than moving it from the front to the back so I believe it cause the thermostat to become stuck and I drove it like that ab 2 and half hours home. Then it over heated one day and shut off and has been doing it since

it is a rebuilt engine not sure how many miles

 

You should probably do what is called a block test. Overheating these motors often leads to coolant seal failure. This could be related to the issues you are seeing.

 

I will give this a try.

A quick update I just left work and drove it back to my barracks about a half miles down the road it made it here and parked it and it has yet to die. Even though it usually dies once I reach a spot

 

ANOTHER UPDATE. I went to put it in gear and reverse and it died on me

 

Nothing diagnostically useful there.

Do the block test. If that comes back normal, get a rotary compression test done.