Hi, I have a 2006 RX8 with 178 k km,manual, 231hp.
Recently I have been suffering some short of hiccups or missfires WOT after 5500 rpm.
I have replaced almost everything, sparkplugs, wires, solenoids ,fuel pump ,air intake, mass air flow sensor, coils, etc more than 1000€ and I still have that damn hiccup, the second o2 sensor, decat pipe and catback exhaust.
I have between 5.2 and 4.9 bar os Compression, so it is low but it can still be driveable.
I have been thinking about switching the secod o2 sensor with the first one to see if something happends.
It pulls hard until it reaches 5500 rpm, when it happens, the car stops accelerating liek 1 second.
thanks for readint, I hope someone can help me.

 

Is there oil in the intake? That can happen on aging engines due to blowby.
ARe there any check engine codes besides the missing cat?

 

Compression wouldnt cause hiccups like that. The rear O2 sensor only reads whether the CAT is working or not. However the front O2 sensor can affect the engine.

No engine codes? Can you rev past 7krpm? Can you manually turn all of your intake valves, SSV and VDI?

Do you have a live monitor OBD tool? Might want to check MAF data, AFR data, maybe even coolant temp data. If you MAF sensor has water in it or has an issue the ECU will essentially put a limiter on the engine around 6krpm I think.

 

​​​​​​When younare stopped you can rev it to redline without problems, when I checked afr it was like 14.7 to 15, I have cel bc the secondafy air fuel pump is deleted p2259 and p0410

 

Almost no oil in intake

 

I can move ssv and vdi without problems, tomorrow I will recieve a vaccum pump to esnure that any of the tiubes of these valves are damaged.

 

Almost no or none at all? There should be zero oil

 

I have ordered the first o2 sensor, it seens that it has to read numvers close to 0 in mA, but mine goes crazy when accelerating to 2000rpm, next week I'll say if this works or not.

 

0mA as long as you're at 14.7 AFR / 1 lambda. Current and voltage will jump around if the mixture changes.
Usually the ECU is good at self diagnosing O2 sensor response, you would see a code.

What are the fuel trims like on a warm 800rpm idle?