i have a 2003 rx8 i am having cold and hot start problems with it. ive put new plugs leads coils in and dyno tuned engine and decarbed aswell. now its having major cold n hot start probs. it starts 1st turn of the key then stops then i have to crank it 4 ages to get it to start wen cold could it be o2 sensor does anybody know ?. please help its costing me so much money

 

How many miles on it?

 

Did this start right after the install of the Leads, Coils and Plugs?
What kind of Leads, Coils and Plugs did you install.

What does a dyno tuned engine have to do with anything? That confuses me?

Cold start issues I have had personal experience with
- Dirty ESS
- Bad Leading, Plug wire (lead)
- Maf disconnected

Hot start issues are typically compression.

Your 2003 RX8 came originally with a slower weaker starter.
Check to make sure you have the upgraded starter, it will help.
It won't fix your problem, but it will help start the car.

 

QUOTE=EDZRIDE;4259622]How many miles on it?[/QUOTE]
970.000

 

970000

 

just leting ppl know wots been done maybe the tune has somthing to do with it ive herd that maybe the injectors arnt tuned properly. dont know wot brand leads n coils r but there 3weeks old. i took it back to the guy he plugged it in n it said weak o2 sensor could that be it