Jimrx8

Hi, before Xmas I had a intermittent problem with power loss and slower start up, I took my rx8 to the garage and they couldn't find anything wrong as it, since xmas and up to a the last week the car had seemed to of fixed itself running like it use too. But now it's come back again! I don't think it's the ignition coils cos why would it come and go away? Would fuel injector cleaner or carbon cleaner help?

wcs

iTrader: (2)

Ummm phew ya
How about this ...

What year
Mileage
Model AT/MT
What was that last thing maintenance wise you did to it?
Last time plugs and coils where changed?
Cleaned the MAF?
Cleaned and Reset the ESS?
Compression Check?
Clogged Catalytic?
Bad fuel pump?
Failed Front O2 sensor?

Jimrx8

its 2007 manual done 30000 miles, had a service back in November and a few weeks after the service the problems started, when i took the car back The garage said they checked everything including sensors and said coils were ok. p.s I'm no car expert lol

wcs

iTrader: (2)

What did they service?

Is the check engine light on?

At what RPM do you notice the power loss?

Slow start up can a be a few things:
Plugs
Coils
Low Compression
Clogged Catalytic
Dirty ESS

Is it a Manual or Auto?

Power Loss can be lots of things:
Plugs
Coils
Catalytic
SSV
APV
ESS
Maf
Compression

If you're not able to diagnose this stuff yourself then you're going to have to go back to the garage.

You're not exactly providing a lot of information or you're unable too because you don't know what to provide.
So basically, trying to figure out what the problem is on a web forum is a shot in the dark.

2hit6

Agreed with WCS.

What rpm is power lost? If it is in the higher rpms, then I could check the cat.

rx8 are known to have clog cats....

That the trouble-shotting process one step at a time and eliminate your variables.

stinner69

Agree with 2hit6 and WCS. Definitely check the cat and get fault codes read. Although the O2 sensor maybe working fine the cat could be clogged especially if the coils, leads, or sparks are at fault as unburnt fuel will be dumped into the cat when you switch the car off.

If its clogged it then the engine struggles to get rid of exhaust gasses which will result in poor fuel to ignition to exhaust flow = loss of power. You can check the physical condition of the cat by removing the O2 sensor (easy - see DIY O2 Sensor thread) and shining a torch into the cat. In mine you could see the a lot of damage to the inside.

Having said all that you need to see what codes are returned as it could be anything as listed by WCS but coils/sparks/cat are the most common issues with 8's.