Hi

I've just bought a used RX-8, 2004 high power edition, manual transmission.
The car has run about 74000 km (roughly 46000 miles).

During test drive, we were not able to notice a weird phenomenon, but I noticed this when I drove the car home after the purcase:

When driving in around 90-100 km per hour (around 55-60 miles per hour) on smaller roads and with traffic, I used the 5th gear a lot, just keeping the rev at around 2600 to around 3000 to check how economical we can drive it during longer trips outside the city.

In slight downhills, I would raise my foot slightly from the gas pedal (but keeping it slightly pressed) and just let the engine keep a stable and smooth run, you know, what you normally do just to keep a stable speed when you are in a slight downhill bit of road. (wether the car accelerates or de- accelerates, all depends on drag).

What I noticed, was that the car would do engine breaking now and then and then return to a normal smooth run, keeping the speed stable.

Is this jerky behavior normal? (I've later experienced this in the 4th gear and as well in in the 6th gear on longer, very slightly downhill parts of the road).
- The 6th gear is very gentle and it is hard to notice, but it's more noticeable in 4th and 5th gear.

Also, the car seem to idle a bit low and a bit unstable as well, varying from around 800 - 1100 on the rev meter when the engine is hot and causing a lot of vibration inside the car.

I have no former experience with rotary engines (I don't even know how they are supposed to sound like on idle). I have no clue about engines either, so when something is up, I usually leave it to the experts.

The former owner put a new air intake and filter on the car, as well as a new effect exhaust(?) unit (for better/more sound, as he put it).

Can it be as simple as a spark plug issue?

Please help a noob out. =)

Regards

K

 

well rotary's do have a tendency to backfire, but mine isnt very jerky. i wouldn't know what to tell you on that. i wouldnt think its a spark plug issue. it would act up more on acceleration. as for the idle, that is not uncommon. if it isnt almost stalling, you should be fine. maybe someone on here should have more insight. im new to rx8's. i'm a seven guy

 

not sure what you mean by the engine braking thing . Maybe you should be in 6th ?

The unstable idle could be caused by the aftermarket intake - what brand is it ?

 

800 to 1100 rpm is normal idle.

Check your coils, plugs, maf sensor, fuel pump, motor mount.